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Open AccessEditorial

Statement of Peer Review

by Giovanna Marrazza, Sara Tombelli, Benoît Piro, Eden Morales-Narváez, Danila Moscone, Michael G. Weller and Shaopeng Wang

Eng. Proc. 2023, 35(1), 40; https://doi.org/10.3390/engproc2023035040 - 5 Sep 2023

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Abstract

In submitting conference proceedings to Engineering Proceedings, the volume editors of the proceedings certify to the publisher that all papers published in this volume have been subjected to peer review administered by the volume editors [...] Full article

(This article belongs to the Proceedings of The 3rd International Electronic Conference on Biosensors)

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2524 KiB

Open AccessProceeding Paper

Self-Assembled Monolayers for Uricase Enzyme Absorption Immobilization on Screen-Printed Gold Electrodes Modified

by Héctor David Hernández, Rocio B. Dominguez and Juan Manuel Gutiérrez

Eng. Proc. 2023, 35(1), 1; https://doi.org/10.3390/IECB2023-14575 - 8 May 2023

Cited by 1 | Viewed by 985

Abstract

Miniaturized and integrated devices for fast determination of clinical biomarkers are in high demand in the current healthcare environment. In this work, we present a functionalized self-assembled monolayer (SAM) on the gold surface of a screen-printed electrode (Au-SPE). The device was applied for [...] Read more.

Miniaturized and integrated devices for fast determination of clinical biomarkers are in high demand in the current healthcare environment. In this work, we present a functionalized self-assembled monolayer (SAM) on the gold surface of a screen-printed electrode (Au-SPE). The device was applied for uric acid (UA) detection, a biomarker associated with arthritis, diabetes mellitus, and kidney function. Prior to SAM formation, AuSPE was subjected to pretreatment with KOH and Au electrodeposition to provide additional roughness to the substrate. The SAM was formed in the AuSPE/KOH/AuNP surface by the cysteamine method—carried out for working surface dipping in the cysteamine (CYS) solution at 20 mM for 24 h (rinsed with ethanol and milli-Q water). Then, the uricase enzyme was immobilized through physical absorption at room temperature for 1 h to obtain the AuSPE/KOH/AuNPs/SAM/Uox biosensor. The physical and electrochemical characterization of AuSPE modification was carried out by scanning electron microscopy (SEM) and cyclic voltammetry (CV). The calibrated data of the Au/KOH/AuNPs/SAM/Uox biosensor showed a linear relation in the range of 50–1000 µM, a sensibility of 0.1449 µA/[(µM)cm²], and a limit of detection (LOD) of 4.4669 µM. The Au/KOH/AuNPs/SAM/Uox also exhibited good selectivity for UA in the presence of ascorbic acid. Moreover, the methodology showed good reproducibility, stability, and sensitive detection of UA. This performance of the proposed biosensor is in good accordance with clinical needs and can be compared with previous biosensors based on nanostructured surfaces of high-fabrication complexity. Full article

(This article belongs to the Proceedings of The 3rd International Electronic Conference on Biosensors)

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Figure 1
General methodology of the AuSPE surface modifications: (<bold>a</bold>) bare AuSPE (WE = Working electrode, CE = Counter electrode, and RE = Reference electrode), (<bold>b</bold>) G working surface activation with KOH/H2O2, (<bold>c</bold>) AuNP electrodeposition by CV with HAuCl4, (<bold>d</bold>) SAM formation by CYS solution for 24 h of incubation, (<bold>e</bold>) SAM structure on working surface, and (<bold>f</bold>) complete assembly: Au/KOH/AuNPs/SAM/Uox biosensor. Full article ">Figure 2
Working surface characterization: (<bold>a</bold>) view at ×300 of gold working electrode morphology, (<bold>b</bold>) view at ×10,000 of the gold working electrode with AuNPs electrodeposited, and (<bold>c</bold>) electrochemical characterization by CV in redox probe K3[FeCN6]/KCl at 5 mM for each working surface modification stage. Full article ">Figure 2 Cont.
Working surface characterization: (<bold>a</bold>) view at ×300 of gold working electrode morphology, (<bold>b</bold>) view at ×10,000 of the gold working electrode with AuNPs electrodeposited, and (<bold>c</bold>) electrochemical characterization by CV in redox probe K3[FeCN6]/KCl at 5 mM for each working surface modification stage. Full article ">Figure 3
UA electrochemical detection: (<bold>a</bold>) UA detection by CV at different concentrations, (<bold>b</bold>) linear regression of the current density depending on the UA concentration, and (<bold>c</bold>) selectivity assay by CV in UA and AA solutions at 1 mM. Full article ">Figure 3 Cont.
UA electrochemical detection: (<bold>a</bold>) UA detection by CV at different concentrations, (<bold>b</bold>) linear regression of the current density depending on the UA concentration, and (<bold>c</bold>) selectivity assay by CV in UA and AA solutions at 1 mM. Full article ">

1083 KiB

Open AccessProceeding Paper

Novel Electrochemical Lactate Biosensors Based on Prussian Blue Nanoparticles

by Vladislav Pleshakov, Elena Daboss and Arkady Karyakin

Eng. Proc. 2023, 35(1), 2; https://doi.org/10.3390/IECB2023-14572 - 8 May 2023

Cited by 4 | Viewed by 1374

Abstract

We report on the novel electrochemical lactate biosensors based on Prussian blue nanoparticles. The immobilization of lactate oxidase was performed through drop-casting on the sensor surface of a mixture containing enzyme, (3-aminopropyl)triethoxysilane and isopropyl alcohol. The apparent Michaelis constant and inactivation constant were [...] Read more.

We report on the novel electrochemical lactate biosensors based on Prussian blue nanoparticles. The immobilization of lactate oxidase was performed through drop-casting on the sensor surface of a mixture containing enzyme, (3-aminopropyl)triethoxysilane and isopropyl alcohol. The apparent Michaelis constant and inactivation constant were determined (0.29 ± 0.03 mM and 0.042 ± 0.002 min⁻¹, respectively) and compared with values obtained for biosensors based on Prussian blue films. The developed lactate biosensors are not inferior in characteristics to those previously known, while the manufacturing process is less laborious. Obtained values also indicate that lactate biosensors based on Prussian blue nanoparticles and lactate oxidase have sufficient sensitivity and operational stability for analytical application in medical and biological research. Full article

(This article belongs to the Proceedings of The 3rd International Electronic Conference on Biosensors)

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1691 KiB

Open AccessProceeding Paper

Assessment of the Freshness of Fish and Poultry Meat by Fast Protein and Metabolite Liquid Chromatography Using a New Optical Sensor

by Georgii Konoplev, Alar Sünter, Artur Kuznetsov, Aleksandr Frorip, Vadim Korsakov, Oksana S. Stepanova, Daniil Lyalin and Oksana V. Stepanova

Eng. Proc. 2023, 35(1), 3; https://doi.org/10.3390/IECB2023-14565 - 8 May 2023

Cited by 1 | Viewed by 1291

Abstract

Fresh fish and poultry meat are in high demand on the market: poultry, mainly chicken, is the second most consumed and the most affordable meat product in the world. Fish consumption varies greatly across regions but, in some countries, seafood is the main [...] Read more.

Fresh fish and poultry meat are in high demand on the market: poultry, mainly chicken, is the second most consumed and the most affordable meat product in the world. Fish consumption varies greatly across regions but, in some countries, seafood is the main source of abundant and affordable macro- and micronutrients. Meat and, especially, fish are highly perishable products; methods and equipment for rapid, objective, and reliable assessing the freshness of fish and meat are crucial for the food industry. Generally recognized reference techniques such as total volatile basic nitrogen (TVB-N), volatile fatty acids (VFA), high pressure liquid chromatography (HPLC), mass spectrometry, or nuclear magnetic resonance (NMR) spectroscopy are time-consuming and require expensive and complex equipment. We developed a novel chromatographic optical sensor with a deep UV LED photometric detection (255–265 nm) for rapid assessment of meat and fish freshness based on determination of the relative content of adenosine triphosphate (ATP) metabolites. The sensor has a simple and compact design, and relatively low cost; sample preparation and processing of a chromatogram takes less than 30 min. The sensor was tested on Amur (farmed freshwater fish) and rooster meat, obtained from a local farmer. The samples were kept refrigerated at +4 °C, measurements were taken daily during a 14 day period. All chromatograms show two peaks: proteins are responsible for the first one; the second broad post-protein band is formed due to the overlapping of individual peaks of ATP and its metabolites. As fish and poultry meat are stored, ATP is converted into metabolites with lower molecular weight, which is reflected in the chromatograms—the elution time for the second peak increases. It was shown that this time can be directly associated with the freshness status of a product. As expected, poultry meat showed better storage stability and freshness retention compared to Amur fish. Full article

(This article belongs to the Proceedings of The 3rd International Electronic Conference on Biosensors)

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1064 KiB

Open AccessProceeding Paper

A Cell-Based Bioelectric Biosensor for Salmonella spp. Detection in Food

by Lazaros Konstantinou, Eleni Varda, Stella Pempetsiou, Theofylaktos Apostolou, Konstantinos Loizou, Lazaros Dougiakis, Antonios Inglezakis and Agni Hadjilouka

Eng. Proc. 2023, 35(1), 4; https://doi.org/10.3390/IECB2023-14564 - 8 May 2023

Cited by 2 | Viewed by 882

Abstract

The prevalence of foodborne diseases is continuously increasing, causing numerous hospitalizations and deaths, as well as money loss in the agri-food sector and food supply chain worldwide. The standard analyses currently used for bacteria detection have significant limitations with the most important being [...] Read more.

The prevalence of foodborne diseases is continuously increasing, causing numerous hospitalizations and deaths, as well as money loss in the agri-food sector and food supply chain worldwide. The standard analyses currently used for bacteria detection have significant limitations with the most important being their long procedural time that can be crucial for foodborne outbreaks. In this study, we developed a biosensor system able to perform robust and accurate detection of Salmonella spp. in meat products after a 3-min analysis. To achieve this, we used a portable device developed by EMBIO Diagnostics called B.EL.D (Bio Electric Diagnostics) and a cell-based biosensor technology (BERA). Results indicated that the new method could detect the pathogen within 24 h after a 3-min analysis and discriminate samples with and without Salmonella with high accuracy (86.1%). The method’s sensitivity, specificity, and positive and negative predictive values ranged from 80 to 90.5%, while the limit of detection was determined to be as low as 10 CFU g⁻¹ in all food substrates. Full article

(This article belongs to the Proceedings of The 3rd International Electronic Conference on Biosensors)

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5 pages, 696 KiB

Open AccessProceeding Paper

Detection of Adulteration of Milk from Other Species with Cow Milk through an Immersible Photonic Immunosensor

by Dimitra Kourti, Michailia Angelopoulou, Konstantinos Misiakos, Eleni Makarona, Anastasios Economou, Panagiota Petrou and Sotirios Kakabakos

Eng. Proc. 2023, 35(1), 5; https://doi.org/10.3390/IECB2023-14582 - 5 Jun 2023

Cited by 6 | Viewed by 987

Abstract

Cow milk is more allergenic than milk from other species, and therefore the adulteration of ewe or goat milk with cow milk can pose a serious threat to consumers. In this work, a silicon-based photonic immunosensor, which includes two U-shaped Mach–Zehnder Interferometers (MZIs), [...] Read more.

Cow milk is more allergenic than milk from other species, and therefore the adulteration of ewe or goat milk with cow milk can pose a serious threat to consumers. In this work, a silicon-based photonic immunosensor, which includes two U-shaped Mach–Zehnder Interferometers (MZIs), was employed for the detection of ewe and goat milk adulteration with cow milk through the immunochemical determination of the milk. The method was fast and sensitive with a detection limit of 0.04 μg/mL bovine k-casein (which corresponds to approximately 0.06% cow milk) in ewe or goat milk, respectively, and with a total assay time of 12 min. Full article

(This article belongs to the Proceedings of The 3rd International Electronic Conference on Biosensors)

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3497 KiB

Open AccessProceeding Paper

Types of EMG Textile Electrodes: A Comparative Study Using PCA

by Bulcha Belay Etana, Benny Malengier, Janarthanan Krishnamoorthy and Lieva Van Langenhove

Eng. Proc. 2023, 35(1), 6; https://doi.org/10.3390/IECB2023-14560 - 8 May 2023

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Abstract

Identifying a suitable textile electrode that would be durable and assist in recording high-quality bio-signal quality is crucial in the production of medical devices. Therefore, this study is aimed at comparing the time domain characteristics of silver-plated-polyamide-embroidered cotton (SPEC), copper-nickel-plated polyester (CNP), and [...] Read more.

Identifying a suitable textile electrode that would be durable and assist in recording high-quality bio-signal quality is crucial in the production of medical devices. Therefore, this study is aimed at comparing the time domain characteristics of silver-plated-polyamide-embroidered cotton (SPEC), copper-nickel-plated polyester (CNP), and stainless-steel-fabric (SSF) dry textile electromyography (EMG) electrodes through principal component analysis (PCA). The standard silver/silver chloride (Ag/AgCl) gel electrode was considered as the reference for all the test textile electrodes mentioned above. The EMG signal was measured by activation of the bicep and tibialis anterior muscles, and the time domain features such as root mean square (RMS) voltage, average rectified value (ARV) voltage, signal to noise ratio (SNR), kurtosis, and skewness were extracted from the EMG signal. The SSF electrode outperformed CNP and SPEC electrodes. Each textile electrode exhibited signal-to-noise ratio (SNR) values comparable to that of the standard electrode. The SNR values were 24.38 dB, 17.72 dB, 15.55 dB, and 13.30 dB for Ag/AgCl, SSF, CNP and SPEC electrodes, respectively. The performance of all the conductive textile electrodes was comparable to that of Ag/AgCl. However, the gel electrode required skin preparation and exhibited short-term stability, whereas, textile electrode materials were long-lasting and could be used for biological signal monitoring at home without the assistance of medical professionals. Full article

(This article belongs to the Proceedings of The 3rd International Electronic Conference on Biosensors)

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1595 KiB

Open AccessProceeding Paper

Immunosensing Cancer Markers through Surface-Enhanced Photoluminescence on Nanostructured Silver Substrates

by Georgia Geka, Anastasia Kanioura, Ioannis Kochylas, Vlassis Likodimos, Spiros Gardelis, Kalliopi Chatzantonaki, Ekaterina Charvalos, Anastasios Dimitriou, Nikolaos Papanikolaou, Anastasios Economou, Sotirios Kakabakos and Panagiota Petrou

Eng. Proc. 2023, 35(1), 7; https://doi.org/10.3390/IECB2023-14583 - 8 May 2023

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Abstract

Noble metal nanostructured substrates enhance photoluminescence emitted from molecules immobilized onto their surface, allowing for the development of highly sensitive immunoassays employing fluorescent labels. In this work, nanostructured silver surfaces were implemented as substrates for the immunochemical detection of two ovarian cancer markers, [...] Read more.

Noble metal nanostructured substrates enhance photoluminescence emitted from molecules immobilized onto their surface, allowing for the development of highly sensitive immunoassays employing fluorescent labels. In this work, nanostructured silver surfaces were implemented as substrates for the immunochemical detection of two ovarian cancer markers, carbohydrate antigen 125 (CA125) and human epididymis protein 4 (HE4). Biotinylated detection antibodies were used to allow for the detection of immunocomplexes through a reaction with streptavidin conjugated to Rhodamine Red-X. The detection limits achieved were 2.5 U/mL and 0.06 ng/mL for CA125 and HE4, respectively, with linear dynamic ranges, covering the concentration ranges of both healthy and ovarian cancer patients. Full article

(This article belongs to the Proceedings of The 3rd International Electronic Conference on Biosensors)

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1359 KiB

Open AccessProceeding Paper

A Novel Dielectric Modulated Misaligned Double-Gate Junctionless MOSFET as a Label-Free Biosensor

by Saurabh Kumar and Rajeev Kumar Chauhan

Eng. Proc. 2023, 35(1), 8; https://doi.org/10.3390/IECB2023-14578 - 8 May 2023

Cited by 4 | Viewed by 974

Abstract

This research paper presents a misaligned double-gate junctionless Metal-Oxide-Semiconductor Field-Effect Transistor for label-free detection of biomolecules. The proposed biosensor combines the advantages of being junctionless, as well as possessing double and misaligned gate MOSFETs, which results in improved sensitivity and selectivity for biological [...] Read more.

This research paper presents a misaligned double-gate junctionless Metal-Oxide-Semiconductor Field-Effect Transistor for label-free detection of biomolecules. The proposed biosensor combines the advantages of being junctionless, as well as possessing double and misaligned gate MOSFETs, which results in improved sensitivity and selectivity for biological recognition. The results show that the proposed biosensor can effectively detect biomolecules and has the potential for use in various applications. Biosensors have become an important tool in various fields, such as healthcare, environmental monitoring, and food safety due to their ability to detect biomolecules. MOSFETs have been widely used as biosensors due to their less complex structure and ease of use. However, traditional MOSFETs have limitations in terms of sensing performance, and there is a need for improved designs that overcome these limitations. The results of this study show that the proposed biosensor can effectively detect various biomolecules, such as protein and DNA. The proposed biosensor design has the potential to revolutionize the field of biosensors. Its combination of improved sensitivity and selectivity makes it a valuable tool for various applications. In conclusion, this research paper presents a dielectric modulated novel misaligned double-gate junctionless MOSFET-based biosensor, promising improved sensing performance in various applications. The proposed design provides a valuable contribution to the field of biosensors and has the potential to revolutionize the way biomolecules are detected. Full article

(This article belongs to the Proceedings of The 3rd International Electronic Conference on Biosensors)

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2141 KiB

Open AccessProceeding Paper

Preliminary Results of the Development of a DNA-Hybridization-Based Biosensor for the Detection of Milk Adulteration Using Gold Interdigitated Electrodes

by Dimitra Karkani, Antonios Georgas, Dimitra P. Houhoula, Angelo Ferraro and Evangelos Hristoforou

Eng. Proc. 2023, 35(1), 9; https://doi.org/10.3390/IECB2023-14567 - 8 May 2023

Viewed by 774

Abstract

Milk is a widely consumed product, and its adulteration is not only common but also very dangerous. This study aimed to develop a biosensor for the detection of milk adulteration using DNA hybridization coupled with an electrochemical device. The advantages of biosensors over [...] Read more.

Milk is a widely consumed product, and its adulteration is not only common but also very dangerous. This study aimed to develop a biosensor for the detection of milk adulteration using DNA hybridization coupled with an electrochemical device. The advantages of biosensors over traditional laboratory methods, such as their speed, ease of use, and cost-effectiveness, are combined with the sensitivity of DNA hybridization. A capacitive biosensor was developed using interdigitated gold electrodes on paper substrate, which were modified with specific oligonucleotides for cow mitochondrial DNA that served as the biorecognition element. The methodology relies on the measurement of changes in capacitance due to DNA hybridization. Preliminary results are presented, showing the ability of this biosensor to detect bovine DNA in goat milk with high sensitivity and specificity. The results show that this biosensor has the potential to be a low-cost, easy-to-perform, and fast method for the detection of milk adulteration. This biosensor technology is a promising development for the detection of milk adulteration and can help to ensure the safety and quality of milk products. Full article

(This article belongs to the Proceedings of The 3rd International Electronic Conference on Biosensors)

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641 KiB

Open AccessProceeding Paper

Micro-Weighing Based Biosensor with Adaptive Interferometry

by Timofey Efimov, Vadim Kumeiko, Roman Romashko, Mikhail Shmelev and Evgeni Rassolov

Eng. Proc. 2023, 35(1), 10; https://doi.org/10.3390/IECB2023-14570 - 8 May 2023

Viewed by 743

Abstract

In this work, an adaptive holographic interferometer was implemented for the measurement of a micromechanical oscillator frequency. A silicon micro-cantilever mounted on a piezoquartz plate was used as the sensing element. Out-of-plane vibrations of the cantilever were excited using a sinusoidal electrical signal. [...] Read more.

In this work, an adaptive holographic interferometer was implemented for the measurement of a micromechanical oscillator frequency. A silicon micro-cantilever mounted on a piezoquartz plate was used as the sensing element. Out-of-plane vibrations of the cantilever were excited using a sinusoidal electrical signal. The cantilever vibrations were measured with the adaptive interferometer using two waves coupling in a semi-insulating photorefractive CdTe:V crystal. In the experiment, the mass of absorbed molecules of bovine serum albumin (BSA) was measured at various concentrations of water solution. The biosensor demonstrated the ability to measure the concentration of BSA in water solutions with a concentration of 0.2 mg/mL. The result shows the possibility of using adaptive interferometry to detect the vibration of micromechanical sensors and the potential prospects for building biosensors based on them. Full article

(This article belongs to the Proceedings of The 3rd International Electronic Conference on Biosensors)

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1051 KiB

Open AccessProceeding Paper

Hydrogel-Coated Nanonet-Based Field-Effect Transistors for SARS-CoV-2 Spike Protein Detection in High Ionic Strength Samples

by Alexandra Parichenko, Wonyeong Choi, Seonghwan Shin, Marlena Stadtmüller, Teuku Fawzul Akbar, Carsten Werner, Jeong-Soo Lee, Bergoi Ibarlucea and Gianaurelio Cuniberti

Eng. Proc. 2023, 35(1), 11; https://doi.org/10.3390/IECB2023-14566 - 8 May 2023

Cited by 1 | Viewed by 881

Abstract

The SARS-CoV-2 pandemic has triggered many studies worldwide in the area of biosensors, leading to innovative approaches for the quantitative assessment of COVID-19. A nanostructured field-effect transistor (FET) is one type of device shown to be ultrasensitive for virus determination. FETs can be [...] Read more.

The SARS-CoV-2 pandemic has triggered many studies worldwide in the area of biosensors, leading to innovative approaches for the quantitative assessment of COVID-19. A nanostructured field-effect transistor (FET) is one type of device shown to be ultrasensitive for virus determination. FETs can be used as transducers to analyze changes in electrical current caused by the bonding of viral molecules to the surface of the semiconducting nanomaterial layer of the FETs. Although nano-transistors require simple setups amenable to be miniaturized for point-of-care diagnostic of COVID-19, this type of sensor usually has limited sensitivity in biological fluids. The reason behind this is the shortened screening length in the presence of high ionic strength solutions. In the frame of this study, we propose a methodology consisting of the FET surface modification with a hydrogel based on the star-shaped polyethylene glycol (starPEG), which hosts specific antibodies against SARS-CoV-2 spike protein in its porous structure. The deposition of the hydrogel increases the effective Debye length, preserving the biosensor’s sensitivity. We demonstrate the capability of silicon nanonet-based FETs to detect viral antigens and cultured viral particles in phosphate-buffered saline (PBS) as well as in human-purified saliva. Finally, we discriminated between positive and negative patients’ nasopharyngeal swab samples. Full article

(This article belongs to the Proceedings of The 3rd International Electronic Conference on Biosensors)

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7 pages, 1823 KiB

Open AccessProceeding Paper

Wearable and Smartphone-Based Sensors in Support of Human-Comfort-Driven Structural Analysis of Building Components

by Chiara Bedon

Eng. Proc. 2023, 35(1), 12; https://doi.org/10.3390/IECB2023-14586 - 9 May 2023

Viewed by 654

Abstract

The continuous progress and advancement of innovation in technology and development of digital tools makes modern structural engineers and technicians of the building and construction sector increasingly able to solve a multitude of design issues. In most of cases, they can take advantage [...] Read more.

The continuous progress and advancement of innovation in technology and development of digital tools makes modern structural engineers and technicians of the building and construction sector increasingly able to solve a multitude of design issues. In most of cases, they can take advantage of, and support from, low-cost and even portable sensors characterized by generally medium-high accuracy and commercial availability. In this paper, the attention is focused on the analysis of recent investigations which have been carried out within the scope of human-comfort-driven structural analysis and design of building components. More precisely, the use of wearable and smartphone-based sensors for the experimental derivation of mechanical parameters of utmost importance and technical interest for the design of pedestrian systems is explored. On the one hand, as shown, the elaborated setup makes it fast and easy to acquire body motion parameters for pedestrians moving on different substructures. At the same time, relevant feedback could possibly be obtained from customers on their corresponding comfort. Full article

(This article belongs to the Proceedings of The 3rd International Electronic Conference on Biosensors)

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Wearable and smartphone-based sensors for (<bold>a</bold>) safety on construction sites or (<bold>b</bold>) comfort-driven design (figure adapted with permission from [<xref ref-type="bibr" rid="B6-engproc-35-00012">6</xref>] under the terms and conditions of the CC-BY license agreement). Full article ">Figure 2
Comfort analysis for pedestrians, with (<bold>a</bold>) an example of a possible mechanical model and (<bold>b</bold>) a scheme of pilot protocol for human-comfort-driven design (figures reproduced with permission from [<xref ref-type="bibr" rid="B6-engproc-35-00012">6</xref>] under the terms and conditions of the CC-BY license agreement). Full article ">Figure 3
Analysis of body vertical acceleration and foot rotation during normal walking, based on wearable sensors. Full article ">Figure 4
Average experimental DLF (<italic>fp</italic> = 1.5 Hz) for a pedestrian on different substructures. Results grouped for (<bold>a</bold>) vertical, (<bold>b</bold>) longitudinal, and (<bold>c</bold>) lateral components of human-induced force. Full article ">Figure 5
Experimental DLF derivation (<italic>fp</italic> = 1.5 Hz) and comparison with experimental evidence in the literature (Rainer and Pernica [<xref ref-type="bibr" rid="B25-engproc-35-00012">25</xref>], Kerr and Bishop [<xref ref-type="bibr" rid="B26-engproc-35-00012">26</xref>]) or analytical models (Young [<xref ref-type="bibr" rid="B27-engproc-35-00012">27</xref>]). Full article ">

4 pages, 775 KiB

Open AccessProceeding Paper

Functionalization of Graphene Oxide for Label-Free Electrochemical Detection of Hepatic Cancer Cells

by Samar Damiati, Shakil A. Awan, Martin Peacock and Bernhard Schuster

Eng. Proc. 2023, 35(1), 13; https://doi.org/10.3390/IECB2023-14599 - 12 May 2023

Viewed by 982

Abstract

In this study, a graphene oxide-modified screen-printed carbon electrode was functionalized with the 1-pyrenebutyric acid-N-hydroxy-succinimide ester and conjugated with antibodies for the label-free detection of human hepatoma HepG2 cells. Using a user-friendly reservoir chamber, the functionalized film was exposed continuously to the cancer [...] Read more.

In this study, a graphene oxide-modified screen-printed carbon electrode was functionalized with the 1-pyrenebutyric acid-N-hydroxy-succinimide ester and conjugated with antibodies for the label-free detection of human hepatoma HepG2 cells. Using a user-friendly reservoir chamber, the functionalized film was exposed continuously to the cancer cells. The use of a continuous flow was intended to enhance the capture of the target cells by the sensing platform. The response of the biosensor was evaluated using cyclic voltammetry. The preliminary data showed good sensitivity for the detection of hepatic cancer cells. The developed biosensor could detect the HepG2 cells from a 1 × 10³ to 3 × 10⁵ cells/mL range. Thus, it is a simple tool for the electrochemical detection of cancer cells and offers a low-cost and disposable sensing platform. Full article

(This article belongs to the Proceedings of The 3rd International Electronic Conference on Biosensors)

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1000 KiB

Open AccessProceeding Paper

Cell Classification Based on Artificial Intelligence Analysis of Cell Images in Microfluidic Chip

by Yuping Yang and Shunbo Li

Eng. Proc. 2023, 35(1), 14; https://doi.org/10.3390/IECB2023-14569 - 8 May 2023

Viewed by 1098

Abstract

We developed a low-cost, multi-classification, label-free and high-precision method for cell classification, which combines microfluidic technology with a deep learning algorithm. The recognition of the states of red blood cells was selected as a typical example to demonstrate the feasibility of the method. [...] Read more.

We developed a low-cost, multi-classification, label-free and high-precision method for cell classification, which combines microfluidic technology with a deep learning algorithm. The recognition of the states of red blood cells was selected as a typical example to demonstrate the feasibility of the method. The microfluidic channel is designed to effectively and controllably solve the problem of cell overlap, which has a severe negative impact on the identification of cells. The object detection model based on YOLOv4 is optimized and used to recognize multiple RBCs simultaneously in the whole field of view, so as to classify them into different morphological subcategories and count the numbers in each subgroup. Full article

(This article belongs to the Proceedings of The 3rd International Electronic Conference on Biosensors)

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2040 KiB

Open AccessProceeding Paper

Contact Lens-Based Intraocular Pressure Sensor

by Syed Ali Raza Bukhari, Tanzila Afrin, Claire Floras and Yongjun Lai

Eng. Proc. 2023, 35(1), 15; https://doi.org/10.3390/IECB2023-14577 - 8 May 2023

Cited by 1 | Viewed by 874

Abstract

The intraocular pressure (IOP) is the principal indicator for diagnosis of glaucoma which is one of the leading causes of blindness. The IOP can vary throughout the day, and traditional methods of measuring it in a clinical setting only provide a fraction of [...] Read more.

The intraocular pressure (IOP) is the principal indicator for diagnosis of glaucoma which is one of the leading causes of blindness. The IOP can vary throughout the day, and traditional methods of measuring it in a clinical setting only provide a fraction of the patient’s IOP pattern. This article presents a cost-effective way for continuous monitoring of IOP by utilizing a soft contact lens with strategically placed holes. The deformation of these holes due to the change in IOP can be used to detect the pressure variations throughout the day. Extensive COMSOL Multiphysics simulations are conducted to optimize the design and to test the viability of this method. The optimized lens design can achieve a large deformation ratio sensitivity of 0.39 per mmHg with an applied pressure range of 10 mmHg to 40 mmHg. Full article

(This article belongs to the Proceedings of The 3rd International Electronic Conference on Biosensors)

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1494 KiB

Open AccessProceeding Paper

Ag/TiO₂ Nanocomposites for Nanothermometry in the Biological Environment

by Roberto Zambon, Marina Franca, Veronica Zani, Roberto Pilot, Silvia Gross, Danilo Pedron and Raffaella Signorini

Eng. Proc. 2023, 35(1), 16; https://doi.org/10.3390/IECB2023-14585 - 8 May 2023

Cited by 1 | Viewed by 705

Abstract

Local temperature determination is essential to understand heat transport phenomena at the nanoscale and to design nanodevices for biomedical, photonic, and optoelectronic applications. In particular, the detection of the local temperature of the intracellular environment is interesting for photothermal therapy. In the present [...] Read more.

Local temperature determination is essential to understand heat transport phenomena at the nanoscale and to design nanodevices for biomedical, photonic, and optoelectronic applications. In particular, the detection of the local temperature of the intracellular environment is interesting for photothermal therapy. In the present work, nanoparticles consisting of an Ag core, covered by a TiO₂ shell and Ag@TiO₂ core–shell, were suitably synthesized through a one-pot method. Silver nanoparticles synthesized in DMF were coated by controlled hydrolysis of titanium tetrabutoxide in the same reaction environment. The synthesis led to nanocomposites where AgNPs were covered by a diffuse layer of anatase. The nanocomposites were characterized using UV/Vis spectroscopy and Raman spectroscopy. The samples obtained proved to be good Raman nanothermometers with a sensitivity comparable to that of simple anatase nanoparticles. Full article

(This article belongs to the Proceedings of The 3rd International Electronic Conference on Biosensors)

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870 KiB

Open AccessProceeding Paper

Nanoparticle/DNAzyme Based Biosensors for Heavy-Metal Ion Detection: Effect of DNAzyme Surface Modifications on Device Sensitivity

by Evangelos Aslanidis, Evengelos Skotadis, Chryssi Panagopoulou, Annita Rapesi, Georgia Tzourmana, George Tsekenis and Dimitris Tsoukalas

Eng. Proc. 2023, 35(1), 17; https://doi.org/10.3390/IECB2023-14581 - 8 May 2023

Cited by 1 | Viewed by 990

Abstract

In this work, a biosensor for heavy metal-ion detection, based on platinum nanoparticles (Pt NPs) and DNAzymes, is presented. Two chemical modification groups were utilized for the DNAzymes’ immobilization on the Pt NPs film. The biosensors were characterized concerning their ability to detect [...] Read more.

In this work, a biosensor for heavy metal-ion detection, based on platinum nanoparticles (Pt NPs) and DNAzymes, is presented. Two chemical modification groups were utilized for the DNAzymes’ immobilization on the Pt NPs film. The biosensors were characterized concerning their ability to detect Lead (Pb²⁺) ions in buffer solutions. Both immobilization techniques exhibit great sensitivity with a detection limit of 25 nM. Full article

(This article belongs to the Proceedings of The 3rd International Electronic Conference on Biosensors)

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1623 KiB

Open AccessProceeding Paper

Biodegradable Mats for the Design of Bifunctional Biosensors for Glucose Detection in Urine

by Nathalia O. Gomes, Rafaella T. Paschoalin, Stanley Bilatto, Amanda R. Sorigotti, Cristiane S. Farinas, Luiz H. C. Mattoso, Sergio A. S. Machado, Osvaldo N. Oliveira Jr. and Paulo A. Raymundo-Pereira

Eng. Proc. 2023, 35(1), 18; https://doi.org/10.3390/IECB2023-14580 - 8 May 2023

Viewed by 999

Abstract

We introduce a bifunctional architecture to construct biosensors on solution-blow spinning fiber mats of polylactic acid (PLA) and polyethylene glycol (PEG). PLA/PEG mats acted as substrate for printing electrodes and as matrix to immobilize glucose oxidase (GOx). Prussian Blue nanoparticles (PB) decorated working [...] Read more.

We introduce a bifunctional architecture to construct biosensors on solution-blow spinning fiber mats of polylactic acid (PLA) and polyethylene glycol (PEG). PLA/PEG mats acted as substrate for printing electrodes and as matrix to immobilize glucose oxidase (GOx). Prussian Blue nanoparticles (PB) decorated working electrodes to detect H₂O₂ from enzymatic catalysis at a low applied potential (0 V vs. Ag/AgCl) with detection limit of 0.197 mM. The inexpensive bifunctional device (<US $0.25 per unit) exhibited a rapid response, long lifetime, and performance similar to the standard method for glucose monitoring in human urine samples. The PLA/PEG mats are sustainable alternative for biosensing and wearable applications. Full article

(This article belongs to the Proceedings of The 3rd International Electronic Conference on Biosensors)

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Representation of the materials used for the fabrication of the device in (<bold>A</bold>). Scheme of the screen-printing protocol in (<bold>B</bold>). Photo of the PLA/PEG electrodes in (<bold>Ci</bold>) and (<bold>Cii</bold>). SEM-FEG images of the PLA/PEG mat and bare surface of WE in (<bold>Ciii</bold>). Images of WE modified with PB nanoparticles in (<bold>Civ</bold>). Reprinted with permission from Ref. [<xref ref-type="bibr" rid="B9-engproc-35-00018">9</xref>]. Copyright 2023 American Chemical Society. Full article ">Figure 2
Fabrication principle of the bifunctional surface. Full article ">Figure 3
(<bold>A</bold>) Schematic representation of the operational principle of bifunctional surface based on PLA/PEG mat. Chronoamperograms obtained for increasing glucose concentration between 0.5 and 5.24 mM using PLA/PEG/SPE/PB (without GOx enzyme) in (<bold>B</bold>) and biosensor in (<bold>C</bold>). (<bold>D</bold>) The resulting calibration curve from the surfaces. All experiments were conducted in artificial urine (pH = 6.0, 0.1 M of KCl) with <italic>E</italic>appl = 0 V (vs. Ag/AgCl) for 30 seconds. Reprinted with permission from Ref. [<xref ref-type="bibr" rid="B9-engproc-35-00018">9</xref>]. Copyright 2023 American Chemical Society. Full article ">Figure 4
Bar plot of glucose determination in undiluted human urine using the biosensor and standard method in (<bold>A</bold>). Interference percentage in (<bold>B</bold>). Stability study during 60 days in (<bold>C</bold>). Reprinted with permission from Ref. [<xref ref-type="bibr" rid="B9-engproc-35-00018">9</xref>]. Copyright 2023 American Chemical Society. Full article ">

7 pages, 1092 KiB

Open AccessProceeding Paper

Electrochemistry of Freely Diffusing Mediators in Polyelectrolyte Membranes Used for Blood Glucose Test Strips with a High Upper Limit of the Linear Range

by Vita Nikitina, Ivan Solovyev and Arkady Karyakin

Eng. Proc. 2023, 35(1), 19; https://doi.org/10.3390/IECB2023-14603 - 16 May 2023

Viewed by 823

Abstract

Co-immobilization of low-molecular-weight mediators and glucose oxidase in polyelectrolyte membranes results in glucose test strips operating in the millimolar concentration range. The density and charge of polyelectrolyte membranes formed on the surface of the screen-printed electrodes allow the diffusion of mediators to be [...] Read more.

Co-immobilization of low-molecular-weight mediators and glucose oxidase in polyelectrolyte membranes results in glucose test strips operating in the millimolar concentration range. The density and charge of polyelectrolyte membranes formed on the surface of the screen-printed electrodes allow the diffusion of mediators to be controlled. Negatively charged perfluorosulfonated ionomer (PFSI) hampers the diffusion of the commonly used ferricyanide (III) ion, while the hexammine ruthenium (III) cation apparent diffusion coefficient in PFSI membrane remains the same as without the membrane. In contrast to PFSI, electrode modification with positively charged chitosan leads to additional adsorption of potassium hexacyanoferrate on the membrane. Additionally, the rate of mediator leakage from the membrane was found to govern the sensitivity of the resulting biosensors. The leakage rate also depends on the density and charge of the polyelectrolyte and mediator. However, the main advantage of the proposed simple approach of single-step deposition of three-component membrane-forming mixtures on the screen-printed electrodes is the extended upper limit of the linearity: 30–50 mM glucose. Hence, the obtained test strips are suitable for glucose detection in undiluted blood. Full article

(This article belongs to the Proceedings of The 3rd International Electronic Conference on Biosensors)

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Fabrication of the test strip based on the screen-printed two-electrode support, with a capillary formed after modification of the working electrode. Full article ">Figure 2
Apparent diffusion coefficients for [Fe(CN)6]3−, [Ru(NH3)6]3+ and Fc(MeOH)2 in the membranes (formed by drop-casting 0.3% polymer solutions on the electrode), 50 mM K2HPO4/KH2PO4, 180 mM NaCl, pH 7.4. Full article ">Figure 3
The relative peak current registered upon release of mediators ([Ru(NH3)6]3+ (<named-content content-type="color:#000099">◆</named-content>), [Fe(CN)6]3− (<named-content content-type="color:#008000">■</named-content>) and Fc(MeOH)2 (<named-content content-type="color:#FF0000">●</named-content>) from the membrane deposited on the electrode via drop-casting 5 mM of mediator in 0.1% chitosan membrane-forming mixtures, cyclic voltammetry, 500 mV s−1, 50 mM K2HPO4/KH2PO4 with 180 mM NaCl, pH 7.4. Full article ">Figure 4
Release rates of [Ru(NH3)6]3+ and [Fe(CN)6]3− (blue and green bars, respectively) from chitosan membranes (formed by drop-casting the mediator in polymer solutions on the electrode) and sensitivity of the glucose test strips based on GOx (10 mg Ml−1) and 100 mM [Ru(NH3)6]3+ or [Fe(CN)6]3− (red and black dots, respectively), 50 mM K2HPO4/KH2PO4, 180 mM NaCl, pH 7.4. Full article ">

2020 KiB

Open AccessProceeding Paper

Directed Evolution of a Genetically Encoded Bioluminescent Ca²⁺ Sensor

by Yufeng Zhao, Sungmoo Lee, Robert E. Campbell and Michael Z. Lin

Eng. Proc. 2023, 35(1), 20; https://doi.org/10.3390/IECB2023-14563 - 8 May 2023

Cited by 1 | Viewed by 986

Abstract

The use of genetically encoded fluorescent sensors for the calcium ion (Ca²⁺) has revolutionized neuroscience research by allowing for the recording of dozens of neurons at the single-cell level in living animals. However, fluorescence imaging has some limitations such as the [...] Read more.

The use of genetically encoded fluorescent sensors for the calcium ion (Ca²⁺) has revolutionized neuroscience research by allowing for the recording of dozens of neurons at the single-cell level in living animals. However, fluorescence imaging has some limitations such as the need for excitation light, which can result in a highly auto-fluorescent background and phototoxicity. In contrast, bioluminescent sensors using luciferase do not require excitation light, making them ideal for non-invasive deep tissue imaging in mammals. Our lab has previously developed a bioluminescent Ca²⁺ sensor CaMBI to image Ca²⁺ activity in the mouse liver, but its responsiveness to Ca²⁺ changes was suboptimal. To improve the performance of this sensor, we applied directed evolution to screen for genetic variants with increased responsiveness. Through several rounds of evolution, we identified variants with more than five times improved responsiveness in vitro. We characterized the improved sensors in culture cell lines and dissociated rat neurons and confirmed that they exhibited a higher sensitivity to changes in intracellular Ca²⁺ levels compared to their progenitor. These optimized Ca²⁺ sensors have the potential for non-invasive imaging of Ca²⁺ activity in vivo, particularly in the brain. Full article

(This article belongs to the Proceedings of The 3rd International Electronic Conference on Biosensors)

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(<bold>a</bold>) Schematic representation of CaMBI. (<bold>b</bold>) Relative total luminescence of CaMBI and Antares3 CaMBI in the presence and absence of Ca2+. (<bold>c</bold>) Luminescence spectra of CaMBI and Antares3 CaMBI. (Error bars represent s.d.). Full article ">Figure 2
Directed evolution of CaMBI. Full article ">Figure 3
(<bold>a</bold>) Relative total luminescence of new CaMBI variants and Antares3 CaMBI in the presence and absence of Ca2+. (<bold>b</bold>) Luminescence spectra of CaMBI variants. (<bold>c</bold>) Luminescence of CaMBI variants at 0, 146 nM, or 39 μM Ca2+. (Error bars represent s.d.). Full article ">Figure 4
(<bold>a</bold>) Representative fluorescence (<bold>upper</bold>) and luminescence (<bold>lower</bold>) microscopic image of L3-P2C9. (<bold>b</bold>) Representative time-lapsed luminescence signals of individual cells upon histamine stimulation (indicated by the arrow). Each trace represents the luminescence signal of a single cell. (<bold>c</bold>) Responses of CaMBI variants to histamine stimulation. (Error bars represent s.e.m.). Full article ">Figure 5
(<bold>a</bold>) Representative luminescence microscopic image of L3-P2C9. (<bold>b</bold>) Representative time-lapsed luminescence signals of individual neurons upon KCl-induced depolarization (indicated by the arrow). (<bold>c</bold>) Responses of CaMBI variants to Ca2+ elevation upon KCl-induced depolarization. (Error bars represent s.e.m.). Full article ">

8 pages, 13029 KiB

Open AccessProceeding Paper

In Silico Analysis of Toehold-Aptamer Sequences Targeting the SARS-CoV-2 Nucleocapsid Protein Gene for Biosensor Development

by Karla M. Esquivel-Ortiz, Aurora Antonio-Pérez and Ana L. Torres-Huerta

Eng. Proc. 2023, 35(1), 21; https://doi.org/10.3390/IECB2023-14718 - 23 May 2023

Viewed by 1090

Abstract

The COVID-19 pandemic has emphasized the need for rapid and affordable on-site virus detection. While enzyme-linked aptamer-based biosensors have proven effective, their utility for SARS-CoV-2 detection remains unexplored. We performed in silico analysis of three toehold-aptamer sequences targeting the SARS-CoV-2 nucleocapsid protein gene, [...] Read more.

The COVID-19 pandemic has emphasized the need for rapid and affordable on-site virus detection. While enzyme-linked aptamer-based biosensors have proven effective, their utility for SARS-CoV-2 detection remains unexplored. We performed in silico analysis of three toehold-aptamer sequences targeting the SARS-CoV-2 nucleocapsid protein gene, with secondary and tertiary structures modeled using mFold and RNAComposer web servers. Molecular docking simulations were challenging due to computational and molecular constraints. Nevertheless, our findings indicate that experimental procedures to assess aptamer–target interactions in vitro under optimal assay conditions are feasible. Successful development of a biosensor using these aptamers could offer a quick and inexpensive method for SARS-CoV-2 detection, addressing the COVID-19 pandemic. Full article

(This article belongs to the Proceedings of The 3rd International Electronic Conference on Biosensors)

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8 pages, 2434 KiB

Open AccessProceeding Paper

Preliminary Studies on the Synthesis of Redox-Labelled Molecularly Imprinted Nanoparticles in Sensor Development for the Quantification of Perfluoroalkyls in Water

by Marco Costa, Sabrina Di Masi, Christopher Zaleski, Sergey A. Piletsky and Cosimino Malitesta

Eng. Proc. 2023, 35(1), 22; https://doi.org/10.3390/IECB2023-14589 - 9 May 2023

Viewed by 877

Abstract

Polyfluoroalkyl compounds (PFASs) are synthetic compounds recently classified as permanent and emerging chemicals ever since their bioaccumulation in humans and the environment, due to the presence of carbon–fluorine functional groups. The design of novel screening tools with addressed high response time for the [...] Read more.

Polyfluoroalkyl compounds (PFASs) are synthetic compounds recently classified as permanent and emerging chemicals ever since their bioaccumulation in humans and the environment, due to the presence of carbon–fluorine functional groups. The design of novel screening tools with addressed high response time for the routine quantification of PFASs in water is highly desirable. In this work, we propose the preparation of a new voltammetric sensor based on molecularly imprinted polymer nanoparticle (nanoMIP) receptors for the highly sensitive and selective quantification of PFASs in water. The nanoMIPs were synthesized by the solid phase approach and immobilized onto functionalized screen-printed platinum electrode (SPPtE), chosen as the transduction element for sensor development. Dimensional characterization of nanoMIPs by Dynamic light scattering (DLS) shows small nanosized imprinted particles (<200 nm) with a polydispersity index (PDI) below 0.3. Electrochemical techniques were used for sensor preparation, characterization, and to assess the analytical performance, respectively. Preliminary calibration curves of nanoMIP-based sensors in a wide range of PFAS concentrations (1.5–100 ng/mL) exhibited high sensitivity toward its target. Full article

(This article belongs to the Proceedings of The 3rd International Electronic Conference on Biosensors)

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General scheme of polymerization protocol. Full article ">Figure 2
Dynamic light scattering analysis (n = 5) of the PFOA-nanoMIPs showing (<bold>a</bold>) particle size distribution and (<bold>b</bold>) the plot of correlation coefficient vs. time (n = 5). Full article ">Figure 3
Electrochemical characterization by (<bold>a</bold>) CV (fifth cycle) and (<bold>b</bold>) DPV in PBS solution for (black) bare screen-printed platinum electrode; (red) functionalized APTES/SPPtE, (blue) after PFOA-nanoMIPs immobilization. DPV condition: (i) Potential range: −0.15 to +0.4 V; (ii) scan rate: 50 mV s−1; (iii) potential step: 4.95 mV; (iv) modulation amplitude: 0.2 V; and (v) time pulse: 20 ms. CV condition: (i) potential range: −0.1 to +0.8 V; (ii) scan rate: 50 mV s−1; and (iii) potential step: 10 mV. Full article ">Figure 4
Electrochemical characterization by DPV in PBS solution for (black) bare screen-printed platinum electrode; (pink) 0.5%, (blue) 1%, (green) 2.5%, and (purple) 5% of APTES in EtOH <italic>v</italic>/<italic>v</italic>. DPV condition: (i) potential range: −0.175 to +0.6 V; (ii) scan rate: 50 mV s−1; (iii) potential step: 4.95 mV; (iv) modulation amplitude: 0.2 V; and (v) time pulse: 20 ms. CV condition: (i) potential range: −0.1 to +0.8 V; (ii) scan rate: 50 mV s−1; and (iii) potential step: 10 mV. Full article ">Figure 5
(<bold>a</bold>) CV and (<bold>b</bold>) DPV measurements performed for PFOA-nanoMIP sensor after exposure to (blank, 0) 1.5, 3, 6, 12, 25, 50, and 100 ng/mL of PFOA dissolved in 5 mM PBS. DPV condition: (i) potential range: −0.15 to +0.4 V; (ii) scan rate: 50 mV s−1; (iii) potential step: 4.95 mV; (iv) modulation amplitude: 0.2 V; and (v) time pulse: 20 ms. CV condition: (i) potential range: −0.1 to +0.8 V; (ii) scan rate: 50 mV s−1; and (iii) potential step: 10 mV. (<bold>c</bold>) Related calibration curve fitted with Hill isotherm of PFOA-nanoMIP sensor. Full article ">Figure 5 Cont.
(<bold>a</bold>) CV and (<bold>b</bold>) DPV measurements performed for PFOA-nanoMIP sensor after exposure to (blank, 0) 1.5, 3, 6, 12, 25, 50, and 100 ng/mL of PFOA dissolved in 5 mM PBS. DPV condition: (i) potential range: −0.15 to +0.4 V; (ii) scan rate: 50 mV s−1; (iii) potential step: 4.95 mV; (iv) modulation amplitude: 0.2 V; and (v) time pulse: 20 ms. CV condition: (i) potential range: −0.1 to +0.8 V; (ii) scan rate: 50 mV s−1; and (iii) potential step: 10 mV. (<bold>c</bold>) Related calibration curve fitted with Hill isotherm of PFOA-nanoMIP sensor. Full article ">

1389 KiB

Open AccessProceeding Paper

Adsorbate Induced Transformations of Ovalbumin Layers in Volatile Organic Solvents: QCM Study of a Potential Bio-Sniffer for Acute Toxicity Assays

by Ivanna Kruglenko, Sergii Kravchenko, Julia Burlachenko, Petro Kruglenko and Boris Snopok

Eng. Proc. 2023, 35(1), 23; https://doi.org/10.3390/IECB2023-14574 - 8 May 2023

Viewed by 769

Abstract

Acute toxicity data are a necessary component of the general analysis of gaseous environments and the prediction of the possible consequences of exposure to a chemical substance on living organisms. One of the fastest ways to obtain such information is to use gas-phase [...] Read more.

Acute toxicity data are a necessary component of the general analysis of gaseous environments and the prediction of the possible consequences of exposure to a chemical substance on living organisms. One of the fastest ways to obtain such information is to use gas-phase chemical sensors with sensitive layers of biological origin. Here we report an experimental study of complex loadings for classical quartz crystal microbalances arising in closely packed protein layers of ovalbumin (OVA) on the surface of polycrystalline silver, silver coated with rigid carbon fullerene C₆₀, or a soft molecular-organic crystal of copper phthalocyanine (CuPc). OVA molecules are similarly immobilized on the silver and fullerene-decorated surfaces, while the response of the OVA-CuPc layer indicates an insignificant amount of protein on the surface. A systematic study of the kinetics of the responses of these layers to saturated vapors of volatile solvents shows that the QCM resonant frequency change correlates well with the toxicity of gaseous analytes. It has been observed that saturated vapors of water, ethanol, and their mixtures are classically adsorbed with a high adsorption capacity. Benzene and isobutanol showed only a non-monotonic anti-Sauerbrey behavior, while acetone and cyclohexane had a 10-fold smaller quasi-classical response. The possibility of a gaseous analyte changing not only the QCM loading but also the mechanical behavior of the protein mass associated with the surface opens up the possibility of observing nonspecific conformational changes in proteins, which can be the cause of general cytotoxicity. This effect, combined with the native conformation of OVA in densely packed protein films, allows the use of ovalbumin in creating sensitive bio-sniffer layers for fast toxicological assays—a new class of express tests for biosafety and environmental control. Full article

(This article belongs to the Proceedings of The 3rd International Electronic Conference on Biosensors)

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The dependences of the response of QCM transducers modified with OVA overlayers when saturated vapor of water (<bold>a</bold>), ethanol (<bold>b</bold>), or brandy (<bold>c</bold>) is pumped over their surface. The approximation of the responses by stretched exponential functions is shown by a dashed line; the parameters of the best fit are shown in parentheses next to the corresponding curve and highlighted in color (Rsat, τ, β). Full article ">Figure 2
Dependences of the response of QCM transducers modified with OVA overlayers when saturated vapors of acetone (<bold>a</bold>) and cyclohexane (<bold>c</bold>) are pumped over their surfaces. The approximation of the responses by stretched exponential functions is shown by a dashed line; the parameters of the best fit are shown in parentheses next to the corresponding curve and highlighted in color (Rsat, τ, β). The inset (<bold>b</bold>) shows an illustration of the silver surface profile (according to atomic force microscopy imaging [<xref ref-type="bibr" rid="B25-engproc-35-00023">25</xref>]) and a layer of OVA dimers [<xref ref-type="bibr" rid="B4-engproc-35-00023">4</xref>] at the same scale. Full article ">Figure 3
The dependences of the response of QCM transducers modified with OVA overlayers when saturated vapors of isobutanol (<bold>a</bold>) and benzene (<bold>c</bold>) pumped over their surfaces. The dashed line is drawn only for the convenience of tracking the nature of the change in frequency. The inset (<bold>b</bold>) shows an illustration of the 3D structure of OVA (built according to PDB DOI: 10.2210/pdb1OVA/pdb using the graphic service of the RCSB Protein Data Bank); magenta highlights the position of 33 aromatic fragments of amino acid residues. Full article ">

7 pages, 1833 KiB

Open AccessProceeding Paper

Construction of a Miniaturized Monosaccharide Detection System Based on Measuring Electric Current and Testing Its Performance Using a Bodipy Fluorescent Dye

by Omar Kerbouche, Mustafa İlker Beyaz and Seda Demirel Topel

Eng. Proc. 2023, 35(1), 24; https://doi.org/10.3390/IECB2023-14587 - 9 Jun 2023

Viewed by 752

Abstract

In this study, a low-cost, miniaturized fluorescence-based measurement system for optical biosensors has been developed. A 3D-printed setup with a blue light-emitting diode (LED) and photodiode was used for electrical detection and monitoring of fluorescence light intensity. The system was used to explore [...] Read more.

In this study, a low-cost, miniaturized fluorescence-based measurement system for optical biosensors has been developed. A 3D-printed setup with a blue light-emitting diode (LED) and photodiode was used for electrical detection and monitoring of fluorescence light intensity. The system was used to explore the fluorescence quenching of boron-dipyrromethene (Bodipy) in the presence of boronic acid functionalized benzyl viologen (o-BBV) to develop a monosaccharide detection platform by studying at different pHs and temperatures. The results showed that the system has potential for further development and optimization. This study provides a proof-of-concept for a low-cost and miniaturized optical biosensor for monosaccharides. Full article

(This article belongs to the Proceedings of The 3rd International Electronic Conference on Biosensors)

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8 pages, 1321 KiB

Open AccessProceeding Paper

Simple Chromatographic Sensor with UV LED Optical Detection for Monitoring Patients Treated with Continuous Ambulatory Peritoneal Dialysis

by Georgii Konoplev, Artur Kuznetsov, Aleksandr Frorip, Alar Sünter, Vadim Korsakov, Oksana Stepanova, Natalia Roschina, Nikolay Ovsyannikov, Roman Gerasimchuk, Alina Isachkina, Zarina Rustamova and Alena Pavshukova

Eng. Proc. 2023, 35(1), 25; https://doi.org/10.3390/IECB2023-14595 - 9 Jun 2023

Cited by 1 | Viewed by 902

Abstract

A novel simple optical sensor based on fast protein liquid chromatography was developed and tested for monitoring end stage renal disease (ESRD) patients treated with continuous ambulatory peritoneal dialysis (CAPD). The device provides direct determination of proteins and lower molecular weight metabolites in [...] Read more.

A novel simple optical sensor based on fast protein liquid chromatography was developed and tested for monitoring end stage renal disease (ESRD) patients treated with continuous ambulatory peritoneal dialysis (CAPD). The device provides direct determination of proteins and lower molecular weight metabolites in effluent peritoneal dialysate using ultraviolet (UV) photometric detection at the wavelengths 285 nm or 260 nm with deep ultraviolet light-emitting diodes. The sensor was calibrated with bovine serum albumin and nucleotides standard solutions. Chromatograms of peritoneal dialysate samples taken from a group of 28 ESRD patients were processed and approximated by a set of split-Gaussian functions. All chromatograms show three overlapping peaks: the first one represents proteins; the other two peaks probably correspond to mid- and low molecular weight metabolites. Strong correlation was reveled between the area of the first peak and total protein concentration determined by a standard biochemical assay, this makes possible estimation of peritoneal protein loss with a reasonable precision less than 15%. The area of the second peak correlated with dialysate optical density at a wavelength 355–365 nm, associated with the UV absorption of advanced glycation end (AGE) products. The third peak correlated with the optical density of the eluate at a wavelength 255–265 nm, associated with the UV absorption of purines and pyrimidines. Thus, we demonstrated the possibility of estimation of proteins and lower molecular weight metabolites in effluent peritoneal dialysate with the compact and affordable chromatographic optical sensor. Full article

(This article belongs to the Proceedings of The 3rd International Electronic Conference on Biosensors)

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Schematic diagram of the sensor. Full article ">Figure 2
Calibration of the FPLC sensor with 2 g/L BSA solution with different sample volumes: (a) The chromatograms; (b) Dependence of the protein half-peak area on the sample volume. Full article ">Figure 3
Calibration of the FPLC sensor with BSA solution with various concentrations: (a) The chromatograms; (b) Dependence of the protein half-peak area on the concentration. Full article ">Figure 4
Calibration of the FPLC sensor with nucleotides solutions: (a) The chromatograms of the nucleotides with the BSA peak as a time reference; (b) Dependence of the elution time on the molecular weight. Full article ">Figure 5
(a) An example of an effluent peritoneal dialysate chromatogram approximated with a set of split Gaussian fitting curves; (b) Dependence of the right half-peak area on total protein concentration determined by a standard biochemical assay. Full article ">Figure 6
Examples of a dialysate UV absorption spectrum: (a) 5 mm cuvette; (b) 30 mm cuvette. Full article ">

8 pages, 6237 KiB

Open AccessProceeding Paper

Biocompatible and Flexible Transparent Electrodes for Skin-Inspired Sensing

by Raquel L. Pereira and Gabriela V. Martins

Eng. Proc. 2023, 35(1), 26; https://doi.org/10.3390/IECB2023-14588 - 9 Jun 2023

Viewed by 887

Abstract

In recent years, flexible electronics have experienced a massive growth as a response to the high demand for new skin-patch sensor devices targeted at personal health-monitoring. In this context, the incorporation of biopolymers into the backbone of these soft systems brings new opportunities [...] Read more.

In recent years, flexible electronics have experienced a massive growth as a response to the high demand for new skin-patch sensor devices targeted at personal health-monitoring. In this context, the incorporation of biopolymers into the backbone of these soft systems brings new opportunities in terms of biocompatibility and sustainability performance. However, the suitable integration of a conductive patterned material is still a challenge, in order to achieve good adhesion and high transparency. Thus, silver nanowires (AgNWs) constitute promising candidates for the fabrication of flexible transparent conductive films. Herein, a chitosan membrane doped with a plasticizer element was made conductive, through a one-step process, by using an optimized ratio of chitosan–lactic acid–AgNWs (Chi-LaA-AgNWs) dispersion. This formulation was applied using screen-printing, and the influence of the polymer ratio, cure temperature, and number of layers applied with the AgNW-based ink was investigated. Compared with conventional water-based AgNW dispersions, the here-proposed chitosan-doped ink enabled the fabrication of transparent electrode platforms holding good stability, homogeneity, and electrical features. Full article

(This article belongs to the Proceedings of The 3rd International Electronic Conference on Biosensors)

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Effect of the number of ink layers on the electrochemical performance of the sensors. CV analysis performed on membranes doped with 2% of glycerine and screen-printed with one to four layers of a Chi-LaA-AgNW dispersion, where the Chi:AgNW mass ratio is 1:1. Ink layers cured for 30 min, at 75 °C. Full article ">Figure 2
Effect of the cure time on the electrochemical performance of the sensors. CV analysis performed on membranes doped with 2% of glycerine and screen-printed with a Chi-LaA-AgNW dispersion, where the Chi:AgNW mass ratio is 1:1. Ink layers cured for 15 min, 30 min, 1 h, or 2 h, at 75 °C. Full article ">Figure 3
Effect of the Chi:AgNW mass ratio of the ink on the electrochemical performance of the sensors. CV analysis performed on membranes doped with 2% of glycerine and screen-printed with 2/3 layers of the Chi-LaA-AgNW dispersion where the Chi:AgNW mass ratio is 1:1 or the unmodified 0.5% (w/w) AgNW suspension. Ink layers cured for 30 min, at 75 °C. Full article ">Figure 4
Effect of the percentage of glycerine in the membranes on the electrochemical performance of the sensors. CV analysis performed on membranes doped with either 1% or 2% of glycerine and screen-printed with 2/3 layers of the Chi-LaA-AgNW dispersion (where the Chi:AgNW mass ratio is 1:1). Ink layers cured for 30 min, at 75 °C. Full article ">

8 pages, 1588 KiB

Open AccessProceeding Paper

Non-Invasive IR-Based Measurement of Human Blood Glucose

by Mhd Ayham Darwich, Anas Shahen, Abbas Daoud, Abdullah Lahia, Jomana Diab and Ebrahim Ismaiel

Eng. Proc. 2023, 35(1), 27; https://doi.org/10.3390/IECB2023-14593 - 9 Jun 2023

Cited by 6 | Viewed by 10468

Abstract

Non-Invasive blood glucose monitoring using infrared (IR) light is considered to be a useful and reliable tool for measuring blood sugar levels during daily activities. IR-based glucose monitoring depends on the variant absorption levels of IR light waves by blood with high or [...] Read more.

Non-Invasive blood glucose monitoring using infrared (IR) light is considered to be a useful and reliable tool for measuring blood sugar levels during daily activities. IR-based glucose monitoring depends on the variant absorption levels of IR light waves by blood with high or low levels of glucose solution. This paper introduces a low-cost finger probe to measure glucose based on Arduino and embedding a Clarke error grid with fuzzy logic. An electronic blood glucose meter was designed and implemented in a non-invasive and painless manner based on an infrared sensor. The electrical signal expressing the level of glucose in the blood with a mathematical equation was used to calibrate and map the physical and electrical values. The final numerical value was validated with the Clarke error grid by implementing fuzzy logic (FL). The designed device was tested on 30 subjects with 15 diabetes subjects. The results show the high significance of results at points where the FL was able to determine an error range of less than 10% of measured glucose within the same range of the reference measurements. The proposed method of using FL with a Clarke error grid gives more confident and precise outputs in cases of this kind of portable device. Full article

(This article belongs to the Proceedings of The 3rd International Electronic Conference on Biosensors)

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1288 KiB

Open AccessProceeding Paper

Detection of Pathogens and Antimicrobial Resistance Genes at Low Concentration via Electrochemical Oligonucleotide Tags

by Neil Gordon, Raj Bawa and Garry Palmateer

Eng. Proc. 2023, 35(1), 28; https://doi.org/10.3390/IECB2023-14584 - 8 May 2023

Viewed by 760

Abstract

Pathogens can be detected electrochemically by measuring guanine oxidation signals generated from RNA or DNA hybridized to a biosensor working electrode. However, the associated limit of detection (LOD) is not sufficiently low for widespread clinical use. Working electrodes employing nanomaterials such as carbon [...] Read more.

Pathogens can be detected electrochemically by measuring guanine oxidation signals generated from RNA or DNA hybridized to a biosensor working electrode. However, the associated limit of detection (LOD) is not sufficiently low for widespread clinical use. Working electrodes employing nanomaterials such as carbon nanotubes successfully reduce the LOD, but nanosensors experience high variability, poor fabrication yield, and high production cost. Our work presented here demonstrates a novel approach for electrochemically detecting low-concentration pathogens and antimicrobial resistance genes that transfers the guanine oxidation source from naturally occurring RNA to synthetic oligonucleotides. In our assay, signal amplification is accomplished by binding RNA from lysed microbial cells to microparticles conjugated with millions of guanine-rich oligonucleotide tags. We employed a sandwich hybridization assay to bind RNA between a screen-printed carbon working electrode conjugated with recognition probes, and a microparticle conjugated with electrochemical oligonucleotide tags. These tags contained a polyguanine detection sequence and an RNA capture sequence on the same oligonucleotide. Single-stranded polyguanine was prefabricated into a quadruplex to enable 8-oxoguanine signals at 0.47 V. This eliminated nonspecific guanine oxidation signals from the RNA, while further reducing the LOD over guanine oxidation. A 70-mer capture sequence was found to be more selective and hybridized faster at room temperature than conventional 20-mer capture sequences. Particle sizes were evaluated from 100 nm to 1.5 µm in diameter, and the larger diameter particles produced greater detection signals. A better performance was obtained by employing magnetic microparticles and magnetically separating magnetic microparticle–RNA complexes from nonspecific materials, such as lysed cell constituents and cell debris, that can interfere with sandwich formation and detection. The high-density magnetic microparticles rested on the electrode surface, causing a portion of the oligonucleotides to adsorb to the working electrode surface. Full article

(This article belongs to the Proceedings of The 3rd International Electronic Conference on Biosensors)

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7 pages, 1823 KiB

Open AccessProceeding Paper

Gold Nanostructure Orchestrated Electrochemical Immunosensor Integrated with Antibody-Electroactive Probe Conjugate for Rapid Detection of SARS-CoV-2 Antibody

by Asmita Gupta, Chansi and Tinku Basu

Eng. Proc. 2023, 35(1), 29; https://doi.org/10.3390/IECB2023-14717 - 12 Jun 2023

Cited by 1 | Viewed by 974

Abstract

Viral detection has been studied predominantly in the last few years, along with the morbidity of COVID-19. Biosensors have been widely used for the detection of various biological molecules, showing a high potential for miniaturization and a friendly approach towards detection. Nanomaterials play [...] Read more.

Viral detection has been studied predominantly in the last few years, along with the morbidity of COVID-19. Biosensors have been widely used for the detection of various biological molecules, showing a high potential for miniaturization and a friendly approach towards detection. Nanomaterials play a significant role in the development of biosensing devices due to their distinct morphological, optical, electrical, chemical, and physical properties, which improve their sensing efficiency. Therefore, the present work reports the fabrication of an electrochemical immunosensor adorned with gold nanoparticles coupled to a redox indicator-labeled antibody conjugate for the rapid detection of SARS-CoV-2 antibodies. The fabricated immunosensor can detect SARS-CoV-2 antibodies within a linear detection range of 10–100 ngmL⁻¹ and offer a sensitivity of 0.013 × 10⁻³ mA ng⁻¹mLmm⁻². The adopted concept can be extended further for the detection of other viral antibodies with high sensitivity and display high prospects for miniaturization, hence offering tremendous commercialization potential. Full article

(This article belongs to the Proceedings of The 3rd International Electronic Conference on Biosensors)

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(a) UV-visible spectroscopy of gold nanoparticles. (b) Electrochemical characterization of nf/ITO and AuNPs/nf/ITO. Full article ">Figure 2
Electrochemical characterization of the fabricated, HRP-pAb/CoV2-Ab/BSA/Spro/AuNPs/nf/ITO immunosensor. Full article ">Figure 3
(a) Concentration; (b) volume optimization of the substrate H2O2 used to activate HRP in HRP-pAb/CoV2-Ab/BSA/Spro/AuNPs/nf/ITO. Full article ">Figure 4
Response studies. (a) Differential Pulse Voltammetry. (b) Calibration curve of the fabricated BSA/Spro/AuNPs/nf/ITO against CoV2-Ab. The red diamond symbol represents the current corresponding to the given concentration(x-axis) of CoV2-Ab, on interaction with fabrictaed BSA/Spro/AuNPs/nf/ITO immunosensor along with the black error bar indicating the standard deviation. Full article ">Figure 5
Response studies. (a) Differential pulse voltammetry. (b) Calibration curve of the fabricated HRP-pAb/CoV2-Ab/BSA/Spro/AuNPs/nf/ITO immunosensor against CoV2-Ab. The red diamond symbol represents the current corresponding to the given concentration(x-axis) of CoV2-Ab, on interaction with fabrictaed HRP-pAb/CoV2-Ab/BSA/Spro/AuNPs/nf/ITO immunosensor along with the black error bar indicating the standard deviation. Full article ">Figure 6
Stability study of the fabricated immunosensor, HRP-pAb/CoV2-Ab/BSA/Spro/AuNPs/nf/ITO. Full article ">

7 pages, 3104 KiB

Open AccessProceeding Paper

Molecularly Imprinted Polymers/Metal–Organic Framework (MIL-53) for Fluorescent Sensing of Ciprofloxacin in Water

by Monika Nehra, Anjali Rohilla, Nisha Beniwal, Neeraj Dilbaghi, Rajesh Kumar and Sandeep Kumar

Eng. Proc. 2023, 35(1), 30; https://doi.org/10.3390/IECB2023-14598 - 12 May 2023

Cited by 1 | Viewed by 1051

Abstract

The contamination of water and food with antibiotics residues poses a severe risk to human health and aquatic environments. The excessive and uncontrolled use of antibiotics is one of the major causes of their presence in the environment. Their continuous consumption willingly or [...] Read more.

The contamination of water and food with antibiotics residues poses a severe risk to human health and aquatic environments. The excessive and uncontrolled use of antibiotics is one of the major causes of their presence in the environment. Their continuous consumption willingly or un-willingly can result in severe health issues such as allergy, headache, hypertension, muscle pain, and hormonal dysfunction. Beside these, the development of antimicrobial resistance (AMR) can make the situation more critical. Therefore, advanced analytical approaches over conventional techniques are required to detect antibiotic residues in a facile and cost-effective manner. The present work deals with the design of fluorescent nanostructures as sensing probes for the detection of ciprofloxacin. Here, we have synthesized NH₂-MIL-53(Al) using a hydrothermal approach. This fluorescent metal–organic framework (MOF) was further combined with molecular imprinted polymers (MIPs) for the selective and specific detection of ciprofloxacin in aqueous solutions. The use of MIPs over other biomolecules (such as antibody, enzymes, and others) is highly promising as it avoids any kind of pre-treatment of the sample. The MIP@NH₂-MIL-53(Al) nanostructure formation is confirmed by performing different characterization techniques involving both spectroscopy and microscopy. The performance of the developed fluorescent composite promotes its applicability for the highly sensitive and specific detection of ciprofloxacin in practical applications. Full article

(This article belongs to the Proceedings of The 3rd International Electronic Conference on Biosensors)

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1963 KiB

Open AccessProceeding Paper

Chemical Transformation of Typical Biological Recognition Elements in Reactions with Nanosized Targets: A Study of Glutathione Coated Silver Nanoparticles

by Sergii Kravchenko, Praskoviya Boltovets and Boris Snopok

Eng. Proc. 2023, 35(1), 31; https://doi.org/10.3390/IECB2023-14571 - 8 May 2023

Cited by 1 | Viewed by 664

Abstract

Glutathione (GT) is a complexing agent that plays a key role in the functioning of a living cell. Gold nanoparticles are often used as transducers of nanosized biosensors, since they have the optical and chemical properties necessary for sensory applications, and make it [...] Read more.

Glutathione (GT) is a complexing agent that plays a key role in the functioning of a living cell. Gold nanoparticles are often used as transducers of nanosized biosensors, since they have the optical and chemical properties necessary for sensory applications, and make it possible to form a sensitive layer with the desired recognition element. Silver nanoparticles (AgNPs) also have attracted increasing interest to sensor applications due to the narrower plasmon resonance band compared to gold nanoparticles, but different surface chemistry. The purpose of this study is to provide an information about GT-coated AgNPs evolution as a system consisting of AgNPs transducer and GT recognition element. AgNPs are transformed through Ag⁺ to amorphous Ag, while GT promotes AgNPs to be dissolved, and gets decomposed by reactive oxygen species (ROS) during the transformation. Full article

(This article belongs to the Proceedings of The 3rd International Electronic Conference on Biosensors)

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9 pages, 1193 KiB

Open AccessProceeding Paper

Effect of Intense Hot-Spot-Specific Local Fields on Fluorescein Adsorbed at 3D Porous Gold Architecture: Evolution of SERS Amplification and Photobleaching under Resonant Illumination

by Iryna Krishchenko, Sergii Kravchenko, Eduard Manoilov, Andrii Korchovyi and Boris Snopok

Eng. Proc. 2023, 35(1), 32; https://doi.org/10.3390/IECB2023-14606 - 16 May 2023

Cited by 2 | Viewed by 760

Abstract

Plasmonic nanostructures with a high density of confined areas with high local electromagnetic fields (hot spots) are sine qua nonto increase the efficiency of surface-enhanced Raman spectroscopy (SERS). These nanostructures can be used both to identify biological molecules and to monitor photochemical reactions [...] Read more.

Plasmonic nanostructures with a high density of confined areas with high local electromagnetic fields (hot spots) are sine qua nonto increase the efficiency of surface-enhanced Raman spectroscopy (SERS). These nanostructures can be used both to identify biological molecules and to monitor photochemical reactions occurring on the metal surface. In this work, using the method of pulsed laser deposition, three-dimensional (3D) porous wedge-shaped arrays of gold nanoparticles (Au NPs) were obtained with structural parameters varying along the substrate, such as film thickness, porosity, nanoparticles size, and the distance between them. The resulting arrays were structures with a regularly changing density of hot spots along the substrate, in which the enhancement of the electromagnetic field strength is due to the geometric parameters of the nanostructure.By analyzing the evolution of fluorescence and Raman scattering of fluorescein molecules adsorbed on the surface of porous gold under illumination at 532 nm, the processes in the region of extreme values of the electromagnetic field of surface nanostructures was studied. A correlation has been established between the amplification of optical signals and the structural features of the surface. A correlation between SERS and fluorescence signals indicates the predominant contribution of hot spots to the electromagnetic amplification of optical signals. The observed time evolution of the fluorescence and SERS intensity of fluorescein can be explained by the combination of molecular photodegradation, the reconstruction of the hot spot architecture due to local heating, and potent relocation of analyte molecules outside the area of measurement owing to the effects of thermal gradients. Full article

(This article belongs to the Proceedings of The 3rd International Electronic Conference on Biosensors)

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(<bold>a</bold>) Dependence of the 3D array thickness of the Au NPs on the distance to the erosion torch axis and (<bold>b</bold>) schematic representation of a wedge-shaped close-packed Au NP nanostructure; arrows indicate the four regions discussed in this work. Full article ">Figure 2
(<bold>a</bold>) Dependence of the SERS signal intensity at 489 cm−1 and (<bold>b</bold>) 1658 cm−1 and (<bold>b</bold>) the fluorescence intensity for fourareas in the substrate plane for porous gold film thickness d. (<bold>c</bold>) Dependence of grains amount N per area of 250 × 250 nm2 on the nanostructure thickness. (<bold>d</bold>) The sections of the profiles of AFM images at a depth of about half the surface profile of the Au NP array (image scale 0.5 μm). Full article ">Figure 3
Dependence of the intensity of Raman scattering and background fluorescence of fluorescein on the time under irradiation of 3D Au NP nanostructures with different film thickness d, the average diameter <italic>D</italic> of Au nanoparticles, and the number <italic>N</italic> of Au grains per 0.0625 μm2: (<bold>a</bold>) <italic>d</italic> = 24 nm, <italic>D</italic> = 19 nm, <italic>N</italic> = 358; (<bold>b</bold>) <italic>d</italic> = 19.5 nm, <italic>D</italic> = 16.5, <italic>N</italic> = 167. Full article ">Figure 4
Time dependence of the intensity of the SERS band at 1658 cm−1 (<bold>a</bold>) and the integral luminescence (<bold>b</bold>) of fluorescein adsorbed on an array of 3D Au NPs for four regions of the surface structure with thickness <italic>d</italic>: 27.5 nm, 24 nm, 19.5 nm, and 14 nm. (<bold>c</bold>) The dependences illustrate the presence of a qualitative correlation between the intensity of the SERS bands at 489 cm−1 (circumference) and 1658 cm−1 (circle)and the level of integrated luminescence for different irradiation times and different parts of the structure under study. Full article ">

3557 KiB

Open AccessProceeding Paper

Smartphone-Adapted Multianalyte Biosensor Platform for Fluorescent Analysis of Human Biomarkers and Immunosuppressive Drugs Using PQQ- and NAD⁺-Dependent Enzymes

by Oleh Smutok and Evgeny Katz

Eng. Proc. 2023, 35(1), 33; https://doi.org/10.3390/IECB2023-14576 - 8 May 2023

Viewed by 767

Abstract

Here, we describe a multianalyte biosensor platform for the fluorescent analysis of different human state biomarkers (α-amylase, phenylalanine, glucose, lactate/pyruvate, alcohol) and some immunosuppressive drugs (cyclosporine A, tacrolimus, methotrexate, rapamycin) using chimeric PQQ- and natural NAD⁺-dependent enzymes. The principle of the [...] Read more.

Here, we describe a multianalyte biosensor platform for the fluorescent analysis of different human state biomarkers (α-amylase, phenylalanine, glucose, lactate/pyruvate, alcohol) and some immunosuppressive drugs (cyclosporine A, tacrolimus, methotrexate, rapamycin) using chimeric PQQ- and natural NAD⁺-dependent enzymes. The principle of the approach is based on the analysis of the brightness of photography of a sensor plate taken with a smartphone camera and processed using ImageJ software. The brightness of the image correlates with the fluorescence intensity of the sensor’s spots which is produced by the enzymatic reduction of phenazine methosulfate or its derivative used as a fluorescence probe at UV 356 nm irradiation, where the amount of the reduced dye depends on the concentration of the target analyte (the enzymatic substrate) in the tested sample. The sensor plate is composed of simple and cheap components, and the procedure of its preparation and usage is easy and does not require any specific skills or expensive instrumentation. The proposed sensor platform is characterized by a high selectivity and storage stability depending on the selectivity and stability characteristics of the used enzyme in an immobilized state. The proposed sensor platform could be used for precision quantitative analysis of a single (or several) analytes or used for a simultaneous qualitative multianalyte assay of them using Boolean logic gates. Full article

(This article belongs to the Proceedings of The 3rd International Electronic Conference on Biosensors)

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(<bold>A</bold>) Schematic presentation of the biocatalytic process generating fluorescent output proportional to the target analyte (glucose) concentration. Abbreviations: GDH—glucose dehydrogenase, Glc—glucose, GlcA—gluconic acid, PQQ and PQQH2—oxidized and reduced forms of pyrroloquinoline quinone, respectively, PMSox and PMSred—phenazine methosulfate oxidized and reduced forms, λex and λem—wavelength maximum of PMSred fluorescence. Figure adapted from [<xref ref-type="bibr" rid="B7-engproc-35-00033">7</xref>] with permission. (<bold>B</bold>) Processing fluorescent image (sensor output) and its analysis with ImageJ software installed on a smartphone. Figure adapted from [<xref ref-type="bibr" rid="B8-engproc-35-00033">8</xref>] with permission. Full article ">Figure 1 Cont.
(<bold>A</bold>) Schematic presentation of the biocatalytic process generating fluorescent output proportional to the target analyte (glucose) concentration. Abbreviations: GDH—glucose dehydrogenase, Glc—glucose, GlcA—gluconic acid, PQQ and PQQH2—oxidized and reduced forms of pyrroloquinoline quinone, respectively, PMSox and PMSred—phenazine methosulfate oxidized and reduced forms, λex and λem—wavelength maximum of PMSred fluorescence. Figure adapted from [<xref ref-type="bibr" rid="B7-engproc-35-00033">7</xref>] with permission. (<bold>B</bold>) Processing fluorescent image (sensor output) and its analysis with ImageJ software installed on a smartphone. Figure adapted from [<xref ref-type="bibr" rid="B8-engproc-35-00033">8</xref>] with permission. Full article ">Figure 2
The components used for the biosensor preparation: VWR fiberglass filter paper, double-sided tape, microscopic glass slides with deposited fiberglass disks, an office hole-puncher for preparing the sensing disks, a multi-pipet, and a smartphone with a camera for taking photos of the biosensor platform. Figure adapted from [<xref ref-type="bibr" rid="B8-engproc-35-00033">8</xref>] with permission. Full article ">Figure 3
(<bold>A</bold>) The scheme of immobilization of enzymes onto SiO2-NPs. (<bold>B</bold>,<bold>C</bold>) Scanning electron microscopy images showing the enzyme-functionalized SiO2-NPs deposited on fiberglass support. (<bold>D</bold>) Microphotography of confocal microscopy visualized the distribution of enzyme-functionalized SiO2-NPs in the sensing spot. The penetration of enzyme-functionalized SiO2-NPs into 125 µm of the glass paper (blue color) support corresponds to app. 625 of single monolayers of SiO2-NPs (200 nm in diameter each). Full article ">Figure 4
The sample photos of the biosensing system for the analysis of glucose (Glc) obtained at different stages of sensor analysis: as prepared, prior to application of glucose, after applying glucose at different concentrations on each sensing spot, after rinsing the sensing spots with buffer, after converting the previous photo to the gray format ready to be processed by the software “ImageJ” installed on a smartphone. Figure adapted from [<xref ref-type="bibr" rid="B8-engproc-35-00033">8</xref>] with permission. Full article ">Figure 5
Selectivity test of the glucose-sensitive biosensor towards possible interferents of common blood serum compounds. Photographs show the sensing plate with the spots reacted with the target analyte glucose and with three interferents—urate, lactate, and ethanol (1 mM each)—and a bar chart showing the fluorescence intensity obtained with the target analyte glucose and with three interferents. The intensity was derived from the image as the brightness of the spots was calculated with the ImageJ software. Figure adapted from [<xref ref-type="bibr" rid="B9-engproc-35-00033">9</xref>] with permission. Full article ">Figure 6
The sample of using the proposed fluorescent biosensor system for multianalyte analysis using Boolean logic gates. Each pair of sensing spots is modified with different enzymes selective to a unique analyte. When all the sensor spots are treated with the same tested sample (e.g., human serum from one patient) the increased amount of some biomarkers will provide the intensive spot’s fluorescence (output <bold>1</bold>) (see intensive blue spots in (<bold>A</bold>)) when their normal level will be taken as “no output” (output <bold>0</bold>) (see dark blue/weakly visible spots in (<bold>A</bold>)). (<bold>B</bold>) The bar chart shows the fluorescence intensity of the spots corresponding to the logic outputs <bold>0</bold> and <bold>1</bold> derived from the images by calculating the image brightness using the ImageJ software. Full article ">

19736 KiB

Open AccessProceeding Paper

Characterization of Spinal Cord Stimulation Electrode for Chronic Implant in Animal Models

by Leila Cavalcanti, Gilberto Filho, Raquel Medeiros, Hudson Diniz, Igor Damasceno, Edgard Morya and Hougelle Simplício

Eng. Proc. 2023, 35(1), 34; https://doi.org/10.3390/IECB2023-14579 - 8 May 2023

Viewed by 936

Abstract

Spinal cord electrical (SCS) stimulation alleviates motor deficits in rodent and primate models of Parkinson’s disease due to a suppression of synchronous corticostriatal low-frequency oscillation. Limited epidural space requires resistant biocompatible microelectrodes to deliver efficiently electrical currents through a metal–cellular interface. Platinum (Pt) [...] Read more.

Spinal cord electrical (SCS) stimulation alleviates motor deficits in rodent and primate models of Parkinson’s disease due to a suppression of synchronous corticostriatal low-frequency oscillation. Limited epidural space requires resistant biocompatible microelectrodes to deliver efficiently electrical currents through a metal–cellular interface. Platinum (Pt) microelectrodes may lead to material degradation and topography modification under prolonged electrical stimulation. Thus, microstimulation performance over time can deteriorate and affect the functional recovery produced by SCS. To investigate electrodes commonly implanted in the epidural space of rats, Pt microelectrodes immersed in physiological saline underwent 48 h of electrical stimulation (100 Hz; 1.0, 1.3, and 1.6 mA). A wettability test was performed to characterize the interaction of the contact angle before and after stimulation, and it was found that there was an increase in this angle after the stimulation. An electrical impedance test showed that electrochemical interactions caused an increase in impedance after the stimulation. A roughness analysis also showed an increase in roughness after stimulation. Pt electrodes under chronic electric stimulation are susceptible to degradation, and further studies can improve electrode stability and efficacy as new sensor technologies become available. Full article

(This article belongs to the Proceedings of The 3rd International Electronic Conference on Biosensors)

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6 pages, 4505 KiB

Open AccessProceeding Paper

Comparative Analysis of the Interaction of Cytochrome C with Supported Lipid Films and DNA Aptamers Using QCM-D Method

by Marek Tatarko, Sandro Spagnolo, Martin Csiba, Veronika Šubjaková and Tibor Hianik

Eng. Proc. 2023, 35(1), 35; https://doi.org/10.3390/IECB2023-14752 - 12 Jun 2023

Cited by 1 | Viewed by 830

Abstract

Cytochrome c (cyt c) is an important indicator of cell apoptosis and can, therefore, be used for the diagnosis of cancer. We performed a comparative analysis of cyt c detection on the surface of lipid films or a monolayer of 11-mercaptoundecanoic acid (MUA) [...] Read more.

Cytochrome c (cyt c) is an important indicator of cell apoptosis and can, therefore, be used for the diagnosis of cancer. We performed a comparative analysis of cyt c detection on the surface of lipid films or a monolayer of 11-mercaptoundecanoic acid (MUA) with immobilized specific or nonspecific DNA aptamers. A quartz crystal microbalance with dissipation monitoring (QCM-D) in a multiharmonic mode was used to study the interaction of cyt c with various surfaces. For this purpose, changes in the resonant frequency, Δf, and dissipation, ΔD, were determined. The strongest interaction of cyt c was observed with sensors based on specific DNA aptamers that were accompanied by a decrease in frequency and an increase in dissipation. The limit of detection (LOD) for this aptasensor was established as 2.89 ± 0.12 nM. The interaction of cyt c with supported lipid films also resulted in a decrease in resonant frequency, but significant changes occurred only in the µM concentration range of cyt c. Changes in dissipation were much lower in comparison with aptamer-based surfaces, which suggests a weaker contribution of cyt c adsorption to the viscosity. Full article

(This article belongs to the Proceedings of The 3rd International Electronic Conference on Biosensors)

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The kinetics of the 3rd to 9th harmonic frequencies, Δf/n, normalized by harmonic number (A) and dissipation ΔD (B) following the addition of specific DNA aptamers (NH2-APT), BSA, and cyt c in the concentration range of 5 nM–10 μM on the MUA layer chemisorbed on the thin gold layer of the piezo crystal. The moments of addition of aptamers, BSA, cyt c, and PBS wash are shown by arrows. Full article ">Figure 2
The kinetics of the 3rd to 9th harmonic frequencies, Δf/n, normalized by harmonic number (A) and dissipation ΔD (B) following the addition of DMPC:DMPG liposomes (0.5 mg/mL) and cyt c in the concentration range 5 nM–10 μM on the chemisorbed layer of DDT on the gold surface of the piezo crystal. The moments of addition of liposomes, cyt c, and PB wash are shown by arrows. Full article ">Figure 3
The plot of the changes in resonant frequency Δf/n (A) and dissipation ΔD (B) vs. cyt c concentration for surfaces based on physically adsorbed BSA on a gold surface (black), specific aptamer (red), nonspecific aptamer (blue), and mixed lipid layer (purple). Measurements were performed in PB. The results are mean ± S.D. obtained for at least 3 independent measurements in each system. Full article ">

6 pages, 1533 KiB

Open AccessProceeding Paper

Combination of On-Chip Electromembrane Extraction with Solid-Phase Microextraction Using a Monolithic Nanocomposite as the Sorbent

by Razieh Zamani and Yadollah Yamini

Eng. Proc. 2023, 35(1), 36; https://doi.org/10.3390/IECB2023-14705 - 18 May 2023

Cited by 4 | Viewed by 1016

Abstract

During the last few decades, many studies have focused on the development of environmentally friendly, efficient, and miniaturized sample preparation methods. In this study, solid-phase microextraction and electromembrane extraction methods were integrated to take advantage of both methods and achieve higher extraction recoveries [...] Read more.

During the last few decades, many studies have focused on the development of environmentally friendly, efficient, and miniaturized sample preparation methods. In this study, solid-phase microextraction and electromembrane extraction methods were integrated to take advantage of both methods and achieve higher extraction recoveries and clean-up. In this regard, Cu/Cr layered double hydroxide was dispersed in a poly(methacrylic acid-co-ethylene glycol dimethacrylate) polymerization mixture, and in situ polymerization was performed in the acceptor phase channel. Thereafter, EME-SPME on a chip was developed to extract non-steroidal anti-inflammatory drugs. The obtained limits of detection were 0.1–0.25 ng mL⁻¹. Under evaluation of this method, extraction recoveries were obtained in the range of 83.34–90.87%, which corresponded to preconcentration factors of 56–61. The method was applied for the extraction of the drugs from real samples such as breast milk, urine, and plasma, and satisfactory results were obtained. Full article

(This article belongs to the Proceedings of The 3rd International Electronic Conference on Biosensors)

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2709 KiB

Open AccessProceeding Paper

MD Average of Vibrational Spectra of Nucleotides in a SERS Sensor Simulation with Varying Number of Au Nanoparticles

by Tatiana Zolotoukhina and Kota Maruyama

Eng. Proc. 2023, 35(1), 37; https://doi.org/10.3390/IECB2023-14568 - 8 May 2023

Viewed by 906

Abstract

Applying the surface-enhanced Raman scattering (SERS) method to detect bioactive molecules such as DNA, proteins, and drugs has significant potential for structure-sensitive nondestructive chemical analysis. The SERS discrimination of single-molecule oligomers in DNA, microRNA, and proteins has attracted wide attention due to the [...] Read more.

Applying the surface-enhanced Raman scattering (SERS) method to detect bioactive molecules such as DNA, proteins, and drugs has significant potential for structure-sensitive nondestructive chemical analysis. The SERS discrimination of single-molecule oligomers in DNA, microRNA, and proteins has attracted wide attention due to the possibility of developing new sensing technology. The collected signal’s sensitivity has the level of detection of single oligomers, which can be compared with the simulation results corresponding to the sensor structure. We investigate the averaging method of the individual bond spectra for DNA nucleotides in the ring part of the pyrimidine (6-ring) and purine (6–5-ring) bases to form vibrational spectra obtained by molecular dynamics (MD) simulation. The system consists of the Au nanoparticles (from 1 to 4 NP assay) attached to a graphene sheet at the edge of the nanopore that localizes in the nanopore nucleotide interaction and spectral enhancement. The nucleotide translocation velocity set at 0.025 m/s compares with the experimental range. The vibrational spectra ring average has been tested for adenine and guanine with close correspondence (in the 500–1700 cm⁻¹ range) to the experimental Raman and SERS spectra and extended to cytosine and thymine nucleotides. We also modified the number of the Au nanoparticles from one NP to four identical NPs to evaluate the influence of the interaction on the MD transient spectra. The variations of mode frequencies and amplitudes due to the number of Au NPs in bond spectra, as well as ring averages, mark the corresponding Au–nucleotide interactions and are considered for use as training sets for machine learning methods. Full article

(This article belongs to the Proceedings of The 3rd International Electronic Conference on Biosensors)

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The structure of the SERS sensor in MD calculations (a) The initial translocation position of cytosine nucleotide at and inside of the graphene pore. The orientation of the nucleotide’s cyclic plane is at 30° to the z–x plane. Atoms are shown: C in gray, N in blue, O in red, and H in light gray. (b) Cytosine (right) is shown with an example of corresponding atom numbering for bonds. (c) Au20 nanoparticle optimized by DFT GGA calculations. (d) Nanopore of 1.5 nm diameter with C bonds at its edge in graphene sheet. Full article ">Figure 2
Simulation models with 1 and 4 Au NPs arranged at the edge of the graphene nanopore and cytosine oligomer at the start of translocation. At the central panel, 4 Au NPs are identical and obtained by the rotation of the initial. Interaction between 3 components is Van der Waals. Full article ">Figure 3
(a) The scheme of the velocity vector projection of the atom on the adjacent bond axes in an autocorrelation function for each bond spectra, (b) the ring bond spectral averages in pyrimidine bases (averaged bonds are marked by yellow arrows, direction of bond summation is shown by blue circle with arrow), (c) the ring averages of purine bases with each atom spectra averaged only once in both pyrimidine (ring 6) and imidazole (ring 5) parts (direction of ring average is shown by blue and red circles, the bond connecting two rings is accounted for only once). Full article ">Figure 4
(a) The vibrational spectra of adenine pyrimidine ring (ring 6), (b) imidazole ring (ring 5), (c) the combined spectra for both rings of adenine with peak frequency values marked by numbers. Full article ">Figure 5
Spectra and modes of cytosine (CYT) with methylated forms 5-Metylcytosine (5MC) and 5-Hydroxymethylcytosine (HMC): (Left pane) ring average of the spectra for 3 forms with mode attribution [<a href="#B44-engproc-35-00037" class="html-bibr">44</a>] of cytosine; (Right pane) comparison of MD and experimental SERS modes, with CYT[1] from ref. [<a href="#B50-engproc-35-00037" class="html-bibr">50</a>] and CYT[2] from ref. [<a href="#B51-engproc-35-00037" class="html-bibr">51</a>] for cytosine nucleotide, modes marked in color are present only in methylated forms of cytosine and have no corresponding experimental values. Reprinted with permission from Ref. [<a href="#B50-engproc-35-00037" class="html-bibr">50</a>]. Copyright 1986 John Wiley & Sons, Ltd. Full article ">Figure 6
(a) Cytosine nucleotide ring average spectra calculated for 1 and 4 Au NPs attached to graphene nanopore (as shown in the upper right pane); (b) the corresponding spectra of 5-methylcytosine; (c) the spectra of 5-hydroxymethylcytosine. Attribution of some spectral peaks is shown for each form of cytosine. Full article ">Figure 7
(a) Random forest prediction for 2-parametric (F and I) dataset, random 0.2 split; (b) prediction for 4-parametric (F, I, ΔF, ΔI) dataset, random 0.2 split (c) prediction for 4-parametric (F, I, ΔF, ΔI) dataset, random and manual 0.2 split; (d) prediction for 4-parametric (F, I, ΔF, ΔI) dataset, random and manual 0.2 split, data from 1 Au NP and 4 Au NP spectra. Full article ">

5 pages, 1517 KiB

Open AccessProceeding Paper

Developing a Sensitive Method for the Electrochemical Determination of Tetracycline Using MB-Tagged Aptamers on Gold Electrode Substrates

by Stefanos Karapetis and Leda G. Bousiakou

Eng. Proc. 2023, 35(1), 38; https://doi.org/10.3390/IECB2023-14597 - 12 May 2023

Viewed by 643

Abstract

An electrochemical aptasensor for the detection of tetracycline (TET) is prepared based on a methylene blue (MB)-tagged DNA aptamer, with the sequence 5′-MB-CCC CCG GCA GGC CAC GGC TTG GGTTGG TCC CAC TGC GCG-thiol-3′. The DNA aptamer is chemisorbed on a gold electrode [...] Read more.

An electrochemical aptasensor for the detection of tetracycline (TET) is prepared based on a methylene blue (MB)-tagged DNA aptamer, with the sequence 5′-MB-CCC CCG GCA GGC CAC GGC TTG GGTTGG TCC CAC TGC GCG-thiol-3′. The DNA aptamer is chemisorbed on a gold electrode and differential pulse voltammetry (DPV) is utilized for the detection. In particular, upon binding of the TET with the purpose-designed aptamer, there is an increase in the current intensity, as a result of the increased proximity of the MB molecule to the gold surface. The sensor is tested using aqueous samples spiked with TET concentrations between 1 and 1000 nM and a limit of detection (LOD) of 1.2 nM is determined. Furthermore, the dissociation constant is estimated to be 1.4 nM using a Lineweaver–Burk plot. Full article

(This article belongs to the Proceedings of The 3rd International Electronic Conference on Biosensors)

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1100 KiB

Open AccessProceeding Paper

In-Silico Evaluation of the Folding and Structural Stability of Aptamers for Application in the Design of a Biosensor for Testosterone Detection

by Ariadna Medina, Ana L. Torres and Aurora Antonio

Eng. Proc. 2023, 35(1), 39; https://doi.org/10.3390/IECB2023-14739 - 31 May 2023

Viewed by 864

Abstract

Currently, dietary supplements contain a wide range of non-specific concentrations of testosterone and/or its synthetic analogs, substances that are not permitted and that pose a risk to public health, which puts into perspective the need to evaluate and regulate the composition of these [...] Read more.

Currently, dietary supplements contain a wide range of non-specific concentrations of testosterone and/or its synthetic analogs, substances that are not permitted and that pose a risk to public health, which puts into perspective the need to evaluate and regulate the composition of these products. The present project proposes a control tool based on the development of a biosensor using aptamers as bio-recognition elements. The aptamer is a specific sequence of oligonucleotides with can fold into unique three-dimensional structures that interact with the analyte (testosterone and analogs). Integrally, it is proposed that the aptamers are coupled with gold nanoparticles functioning as a census and signal transduction system conducing to a biosensor with high sensitivity and selectivity and rapid response. In this work, modeling and molecular docking tools were used to evaluate the folding and structural stability of the aptamers. It is essential to carry out complete in silico analysis for the bio-recognition system and to evaluate the stability of the proposed aptamers with variations in the medium, allowing one to determine the conditions and adaptations necessary for the experimental analysis, design, and operation of the biosensor. On the other hand, evaluating the affinity and identifying the types of interactions between the aptamer and analyte allows us to locate the best candidate for the proposed aptamers. The stability of a set of nine sequences with proven interaction with testosterone was evaluated under different conditions, specifically, folding temperature (8.0 °C, 20 °C, and 30 °C), [Na⁺] (1.0 mm M, 50 mM, and 150 mM) and [Mg²⁺] (1.0 mm M, 2.0 mM, 3.0 mM, and 4.0 mM), with the MFold web server, RNA Composer, and PyMOL. The affinity and molecular interaction assays were carried out between each of the aptamers and three analytes: testosterone, testosterone undecanoate, and androstenedione using Auto dock Vina, Chimera, PyMOL, and Discovery Studio. The results showing stability and conformational changes in the aptamers allow us to conclude that the aptamers (T6, T5.1, and TESS1) are compatible with the conditions used in run tests and have high affinity for testosterone, the interactions of which are mainly established through non-covalent and hydrogen bonds. Full article

(This article belongs to the Proceedings of The 3rd International Electronic Conference on Biosensors)

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