Biosensors

13 pages, 1619 KiB

Open AccessArticle

Efficient Entrapment of Alpha-Synuclein Biotinylated Antibody in KCC-1-NH-CS₂ and Application for the Sensitive Diagnosis of Parkinson’s Using Recognition of Biomarker: An Innovative Electrochemical Label-Free Immunosensor for the Biomedical Analysis of Neurodegenerative Diseases

by Hossein Navay Baghban, Mohammad Hasanzadeh, Yuqian Liu and Farzad Seidi

Biosensors 2022, 12(10), 911; https://doi.org/10.3390/bios12100911 - 21 Oct 2022

Cited by 5 | Viewed by 2257

Abstract

The early detection of Parkinson’s disease (PD) is a critical issue in terms of efficiency. Alpha-synuclein (α-Syn) is a biomarker in PD checks. Alpha-synuclein (α-syn) is the major constituent of Lewy bodies and a pathogenic hallmark of all synucleinopathies, including PDs, dementia with [...] Read more.

The early detection of Parkinson’s disease (PD) is a critical issue in terms of efficiency. Alpha-synuclein (α-Syn) is a biomarker in PD checks. Alpha-synuclein (α-syn) is the major constituent of Lewy bodies and a pathogenic hallmark of all synucleinopathies, including PDs, dementia with Lewy bodies, and multiple system atrophy. In this study, KCC-1-NH-CS₂ was conjugated with biotinylated Ab and entrapped in P(β-CD) polymer cavities. Using this approach, a novel electrochemical label-free immunosensor was designed for the quantification of α-syn in real human samples. For this purpose, the glassy carbon electrode electropolymerized with P(β-CD) biopolymer provided an excellent matrix for entrapping of KCC-1-NH-CS₂ loaded with the biotinylated antibody of α-syn. Using the chronoamperometric technique, the proposed immunosensor shows a suitable range of 0.02 to 64 ng/mL for the determination of α-syn. Additionally, a low limit of quantification of the engineered biosensor was obtained at 0.02 ng/mL. The developed immunosensor’s adequate stability, sensitivity, and selectivity, together with its ease of manufacture, make it a promising diagnostic technique for further research. This study also will pave the way for further applications of the synergetic effect of β-CD and KCC-1-NH-CS₂ for biomedical analysis in the near future. Full article

(This article belongs to the Special Issue Advances in Amplification Methods for Biosensors)

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(A) CV characterization of step-by-step fabrication of immunosensor, the supporting electrolyte was 0.05 M solution [Fe (CN)6]3−/4−/KCl with a potential range from −1 to 1, scan rate = 0.1 V/s. (B) Comparison of peak currents recorded in the process of immunosensor fabrication. Full article ">Figure 2
ChA curves of the GCE-P(β-CD)-KCC-1-NH-CS2 in different concentrations of α-Syn (0.02, 2, 4, 8, 16, 64 ng/mL). The supporting electrolyte is 0.01 M ferricyanide/ferrocyanide. The applied potential was 0.3 V vs. Ag/AgCl, and the record time was set to 140 s. Inset: related calibration curve (n = 4, SD = 2.44). Full article ">Figure 3
(A) CV of GCE-P(β-CD) at scan rates ranging from 0.002 to 1 V/s. (B) Dependence of the Epa vs. Lnv. (C) Dependence of LnIp vs. Lnv. (D) Dependence of Ip to the square root of sweep rates. Full article ">Figure 4
(A) DPV of GCE-β-CD–KCC-1-NH-CS2-Ab-BSA in the presence of 16 ng/mL α-syn in three repetitions. The supporting electrolyte was 0.05 M solution [Fe (CN)6]3−/4−/KCl; the potential range was from -1 to 1. (B) Comparison of 1st, 2nd, and 3rd peak currents (SD = 2.13, n = 4). Full article ">Scheme 1
The fabrication procedure of the electrochemical immunosensor for the recognition of α-syn biomarker. Full article ">

78 pages, 16259 KiB

Open AccessReview

Graphene and Its Derivatives: Synthesis and Application in the Electrochemical Detection of Analytes in Sweat

by Anoop Singh, Aamir Ahmed, Asha Sharma and Sandeep Arya

Biosensors 2022, 12(10), 910; https://doi.org/10.3390/bios12100910 - 21 Oct 2022

Cited by 29 | Viewed by 6739

Abstract

Wearable sensors and invasive devices have been studied extensively in recent years as the demand for real-time human healthcare applications and seamless human–machine interaction has risen exponentially. An explosion in sensor research throughout the globe has been ignited by the unique features such [...] Read more.

Wearable sensors and invasive devices have been studied extensively in recent years as the demand for real-time human healthcare applications and seamless human–machine interaction has risen exponentially. An explosion in sensor research throughout the globe has been ignited by the unique features such as thermal, electrical, and mechanical properties of graphene. This includes wearable sensors and implants, which can detect a wide range of data, including body temperature, pulse oxygenation, blood pressure, glucose, and the other analytes present in sweat. Graphene-based sensors for real-time human health monitoring are also being developed. This review is a comprehensive discussion about the properties of graphene, routes to its synthesis, derivatives of graphene, etc. Moreover, the basic features of a biosensor along with the chemistry of sweat are also discussed in detail. The review mainly focusses on the graphene and its derivative-based wearable sensors for the detection of analytes in sweat. Graphene-based sensors for health monitoring will be examined and explained in this study as an overview of the most current innovations in sensor designs, sensing processes, technological advancements, sensor system components, and potential hurdles. The future holds great opportunities for the development of efficient and advanced graphene-based sensors for the detection of analytes in sweat. Full article

(This article belongs to the Special Issue Advances in Materials and Chemistry for Wearable Biosensors and Bioelectronics)

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Graphical abstract

12 pages, 3748 KiB

Open AccessArticle

Glucose Incorporated Graphite Matrix for Electroanalysis of Trimethoprim

by Rakesh R. Sawkar, Mahesh M. Shanbhag, Suresh M. Tuwar, Ravindra S. Veerapur and Nagaraj P. Shetti

Biosensors 2022, 12(10), 909; https://doi.org/10.3390/bios12100909 - 21 Oct 2022

Cited by 5 | Viewed by 1981

Abstract

The antibiotic drug trimethoprim (TMP) is used to treat bacterial infections in humans and animals, and frequently TMP is used along with sulfonamides. However, a large portion of TMP is excreted in its active state, which poses a severe problem to humans and [...] Read more.

The antibiotic drug trimethoprim (TMP) is used to treat bacterial infections in humans and animals, and frequently TMP is used along with sulfonamides. However, a large portion of TMP is excreted in its active state, which poses a severe problem to humans and the environment. A sensitive, rapid, cost-effective analytical tool is required to monitor the TMP concentration in biological and environmental samples. Hence, this study proposed an analytical methodology to analyze TMP in clinical, biological and environmental samples. The investigations were carried out using a glucose-modified carbon paste electrode (G-CPE) employing voltammetric techniques. Electrochemical behavior was examined with 0.5 mM TMP solution at optimum pH 3.4 (Phosphate Buffer Solution, I = 0.2 M). The influence of scan rate on the electro-oxidation of TMP was studied within the range of 0.05 to 0.55 V/s. The effect of pH and scan rate variations revealed proton transfer during oxidation. Moreover, diffusion phenomena governed the irreversibility of the electrode reaction. A probable and suitable electrode interaction and reaction mechanism was proposed for the electrochemical oxidation of TMP. Further, the TMP was quantitatively estimated with the differential pulse voltammetry (DPV) technique in the concentration range from 9.0 × 10⁻⁷ to 1.0 × 10⁻⁴ M. The tablet, spiked water and urine analysis demonstrated that the selected method and developed electrode were rapid, simple, sensitive, and cost-effective. Full article

(This article belongs to the Special Issue Electrochemical (Bio-) Sensors in Biological Applications)

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14 pages, 3570 KiB

Open AccessArticle

A Novel Activated Biochar-Based Immunosensor for Rapid Detection of E. coli O157:H7

by Abdus Sobhan, Fei Jia, Lisa Cooney Kelso, Sonatan Kumar Biswas, Kasiviswanathan Muthukumarappan, Changyong Cao, Lin Wei and Yanbin Li

Biosensors 2022, 12(10), 908; https://doi.org/10.3390/bios12100908 - 21 Oct 2022

Cited by 9 | Viewed by 2506

Abstract

E. coli O157:H7, one of the major foodborne pathogens, can cause a significant threat to the safety of foods. The aim of this research is to develop an activated biochar-based immunosensor that can rapidly detect E. coli O157:H7 cells without incubation in pure [...] Read more.

E. coli O157:H7, one of the major foodborne pathogens, can cause a significant threat to the safety of foods. The aim of this research is to develop an activated biochar-based immunosensor that can rapidly detect E. coli O157:H7 cells without incubation in pure culture. Biochar was developed from corn stalks using proprietary reactors and then activated using steam-activation treatment. The developed activated biochar presented an enhanced surface area of 830.78 m²/g. To develop the biosensor, the gold electrode of the sensor was first coated with activated biochar and then functionalized with streptavidin as a linker and further immobilized with biotin-labeled anti-E. coli polyclonal antibodies (pAbs). The optimum concentration of activated biochar for sensor development was determined to be 20 mg/mL. Binding of anti-E. coli pAbs with E. coli O157:H7 resulted in a significant increase in impedance amplitude from 3.5 to 8.5 kΩ when compared to an only activated biochar-coated electrode. The developed immunosensor was able to detect E. coli O157:H7 cells with a limit of detection of 4 log CFU/mL without incubation. Successful binding of E. coli O157:H7 onto an activated biochar-based immunosensor was observed on the microelectrode surface in scanning electron microscopy (SEM) images. Full article

(This article belongs to the Section Biosensor and Bioelectronic Devices)

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14 pages, 2171 KiB

Open AccessArticle

Trace Determination of Grouper Nervous Necrosis Virus in Contaminated Larvae and Pond Water Samples Using Label-Free Fiber Optic Nanoplasmonic Biosensor

by Yuan-Yu Chen, Chih-Lu Wu, Chia-Wei Hsu, Chih-Hui Wang, Chung-Rui Su, Chun-Jen Huang, Hau-Ren Chen, Lai-Kwan Chau and Shau-Chun Wang

Biosensors 2022, 12(10), 907; https://doi.org/10.3390/bios12100907 - 21 Oct 2022

Cited by 2 | Viewed by 1958

Abstract

We developed a fast (<20 min), label-free fiber optic particle plasmon resonance (FOPPR) immunosensing method to detect nervous necrosis virus (NNV), which often infects high-value economic aquatic species, such as grouper. Using spiked NNV particles in a phosphate buffer as samples, the standard [...] Read more.

We developed a fast (<20 min), label-free fiber optic particle plasmon resonance (FOPPR) immunosensing method to detect nervous necrosis virus (NNV), which often infects high-value economic aquatic species, such as grouper. Using spiked NNV particles in a phosphate buffer as samples, the standard calibration curve obtained was linear (R² = 0.99) and the limit of detection (LOD) achieved was 2.75 × 10⁴ TCID₅₀/mL, which is superior to that obtained using enzyme-linked immunosorbent assay (ELISA). By using an enhancement method called fiber optic nanogold-linked immunosorbent assay (FONLISA), the LOD can be further improved to <1 TCID₅₀/mL, which is comparable to that found by the conventional qPCR method. Employing the larvae homogenate samples of NNV-infected grouper, the results obtained by the FOPPR biosensor agree with those obtained by the quantitative polymerase chain reaction (qPCR) method. We also examined pond water samples from an infected container in an indoor aquaculture facility. The lowest detectable level of NNV coat protein was found to be 0.17 μg/mL, which is one order lower than the LOD reported by ELISA. Therefore, we demonstrated the potential of the FOPPR biosensor as an outbreak surveillance tool, which is able to give warning indication even when the trend of larvae death toll increment is still not clear. Full article

(This article belongs to the Special Issue Waveguide Biosensors)

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The schematic illustration of FOPPR biosensor system used in this study: A. light-emitting diode (LED); B. sensing chip; C. sample inlet port; D. sample outlet port; E. sensing fiber with one unclad segment; F. photodiode; G. circuit board with LED driver and photoreceiver amplification circuit; H. data acquisition card; I. personal computer. In the upper right, the left imbedded photograph shows the upper and lower slides of a sensor chip, while the right photograph shows the sensing fiber with one unclad segment. Full article ">Figure 2
(a) The sensorgram obtained by sequentially injecting NNV standard solutions at concentration of (1) 1.0 × 103, (2) 2.5 × 103, (3) 5.0 × 103, (4) 7.5 × 103, (5) 1.0 × 104, (6) 2.5 × 104, (7) 5.0 × 104, (8) 7.5 × 104, (9) 1.0 × 105, (10) 2.5 × 105, and (11) 5.0 × 105 TCID50/mL. (b) The standard calibration curve of the normalized response (ΔI/I0) versus the logarithm value of NNV concentration (log[C]). Each point is the mean of 3 repeated measurements. Full article ">Figure 3
The sensorgram obtained by sequentially injecting diluted filtrate samples of NNV-infected larvae homogenate with dilution factor of (1) 320, (2) 160, (3) 80, and (4) 40. Full article ">Figure 4
(a) The sensorgram obtained by sequentially injecting NNV standard solutions at concentrations of (1) 1.0 × 100, (2) 1.0 × 101, (3) 1.0 × 102, (4) 1.0 × 103, and (5) 1.0 × 104 TCID50/mL in the presence of AuNP@AbD conjugate. (b) The standard calibration curve of the normalized response (ΔI/I0) versus the logarithm value of NNV concentration (log[C]). Full article ">Figure 5
(a) The sensorgram obtained by sequentially injecting NNV coat protein standard solutions at concentrations of (1) 1.4 × 10−7, (2) 2.8 × 10−7, (3) 5.6 × 10−7, (4) 1.25 × 10−6, (5) 2.5 × 10−6, (6) 5.0 × 10−6, (7) 1.0 × 10−5, and (8) 2.0 × 10−5 to g/mL. (b) The corresponding standard calibration curve of the normalized response (ΔI/I0) versus the logarithm value of NNV coat protein concentration (log[C]), over the range of 1.4 × 10−7 to 2.5 × 10−6 g/mL. Full article ">Figure 6
The detected concentration of NNV coat proteins in an infected pond using FOPPR biosensor (curve A) from the eighth day to the nineteenth day during a larvae cultivation process; the death toll of grouper larvae (curve B) in the same time span. Full article ">Scheme 1
Schematic of the steps involved in the fabrication of sensing fibers and the corresponding biosensing strategies for (a) direct method and (b) FONLISA method. Full article ">

14 pages, 36650 KiB

Open AccessCommunication

An Innovative Simple Electrochemical Levofloxacin Sensor Assembled from Carbon Paste Enhanced with Nano-Sized Fumed Silica

by Amany M. Fekry

Biosensors 2022, 12(10), 906; https://doi.org/10.3390/bios12100906 - 21 Oct 2022

Cited by 13 | Viewed by 2184

Abstract

A new electrochemical sensor for the detection of levofloxacin (LV) was efficiently realized. The aim was to develop a new, cheap, and simple sensor for the detection of LV, which is used in various infections due to its pharmacological importance. It consists of [...] Read more.

A new electrochemical sensor for the detection of levofloxacin (LV) was efficiently realized. The aim was to develop a new, cheap, and simple sensor for the detection of LV, which is used in various infections due to its pharmacological importance. It consists of carbon paste (CP) enhanced with nano-sized fumed silica (NFS). NFS has a very low bulk density and a large surface area. The carbon paste-enhanced NFS electrode (NFS/CPE) showed great electrocatalytic activity in the oxidation of 1.0 mM LV in Britton–Robinson buffer (BR) at pH values ranging from 3.0 to 8.0. Cyclic voltammetry (CV) and differential pulse voltammetry (DPV) were used; the peak current value (I_p) of the NFS/CPE sensor was 2.7 times that of the bare electrode, ensuring its high electrocatalytic activity. Electrochemical impedance spectroscopy (EIS) was performed at a peak potential (E_p) of +1066 mV, yielding a resistance of 10 kΩ for the designed NFS/CPE sensor compared to 2461 kΩ for the bare electrode, indicating the high conductivity of the modified sensor and verifying the data observed using the CV technique. Surface descriptions were determined by scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDX). The variation in the concentration of LV (2.0 to 1000 µM) was considered in BR buffer (pH = 5.0) at a scan rate (SR) of 10 mV/s by the NFS/CPE. The detection and quantification limits were 0.09 µM and 0.30 µM, respectively. To evaluate the application of LV in real samples, this procedure was established on Quinostarmax 500 mg tablets and human plasma samples. Reasonable results were obtained for the detection of LV. Full article

(This article belongs to the Special Issue Low-Dimensional Materials in Biosensors, Biophotonics, and Bioelectronics)

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SEM images of (A) CPE and (B) NFS/CPE electrodes; (C) TEM image (size distribution histogram as inset); and (D) EDX spectra of nano-sized fumed silica improved carbon paste electrode. Full article ">Figure 2
(A) CVs (SR = 50 mV/s) and Nyquist plots (at peak potential) of 1 mM LV using BR buffer (pH 5.0) at (B) CPE and (C) NFS/CPE. Inset C: fitting model. Full article ">Figure 3
CVs of LV at dissimilar pH values by NFS/CPE, at a scan rate of 50 mV/s. Inset: (A) Deviation of anodic peak current (Ipa), and (B) potential (Epa), with pH at NFS/CPE. Full article ">Figure 4
(A) CVs of 1.0 mM LV in BR (pH 5.0) by means of various SRs (10.0–400 mV s−1). Inset: The Ipa against the square root of SR at NFS/CPE. (B) The logarithm of the Ipa and the logarithm of the SR at NFS/CPE. (C) The Epa against the logarithm of the SR at NFS/CPE. (D) The Ipa against the square root of SR at CPE. Full article ">Figure 4 Cont.
(A) CVs of 1.0 mM LV in BR (pH 5.0) by means of various SRs (10.0–400 mV s−1). Inset: The Ipa against the square root of SR at NFS/CPE. (B) The logarithm of the Ipa and the logarithm of the SR at NFS/CPE. (C) The Epa against the logarithm of the SR at NFS/CPE. (D) The Ipa against the square root of SR at CPE. Full article ">Figure 5
Outcome of the accumulation of time on Ipa for 1.0 mM of LV in BR (pH 5.0) at NFS/CPE. Inset: the corresponding data as CVs. Full article ">Figure 6
Calibration curve of LV using NFS/CPE. Full article ">Figure 7
Instantaneous determination of 6 × 10−4 M LV and ACOP. Full article ">Scheme 1
Recommended oxidation reaction mechanism of LV. Full article ">

22 pages, 2405 KiB

Open AccessFeature PaperEditor’s ChoiceReview

Bacteriophage-Based Biosensors: A Platform for Detection of Foodborne Bacterial Pathogens from Food and Environment

by Rashad R. Al-Hindi, Addisu D. Teklemariam, Mona G. Alharbi, Ibrahim Alotibi, Sheren A. Azhari, Ishtiaq Qadri, Turki Alamri, Steve Harakeh, Bruce M. Applegate and Arun K. Bhunia

Biosensors 2022, 12(10), 905; https://doi.org/10.3390/bios12100905 - 21 Oct 2022

Cited by 29 | Viewed by 6055

Abstract

Foodborne microorganisms are an important cause of human illness worldwide. Two-thirds of human foodborne diseases are caused by bacterial pathogens throughout the globe, especially in developing nations. Despite enormous developments in conventional foodborne pathogen detection methods, progress is limited by the assay complexity [...] Read more.

Foodborne microorganisms are an important cause of human illness worldwide. Two-thirds of human foodborne diseases are caused by bacterial pathogens throughout the globe, especially in developing nations. Despite enormous developments in conventional foodborne pathogen detection methods, progress is limited by the assay complexity and a prolonged time-to-result. The specificity and sensitivity of assays for live pathogen detection may also depend on the nature of the samples being analyzed and the immunological or molecular reagents used. Bacteriophage-based biosensors offer several benefits, including specificity to their host organism, the detection of only live pathogens, and resistance to extreme environmental factors such as organic solvents, high temperatures, and a wide pH range. Phage-based biosensors are receiving increasing attention owing to their high degree of accuracy, specificity, and reduced assay times. These characteristics, coupled with their abundant supply, make phages a novel bio-recognition molecule in assay development, including biosensors for the detection of foodborne bacterial pathogens to ensure food safety. This review provides comprehensive information about the different types of phage-based biosensor platforms, such as magnetoelastic sensors, quartz crystal microbalance, and electrochemical and surface plasmon resonance for the detection of several foodborne bacterial pathogens from various representative food matrices and environmental samples. Full article

(This article belongs to the Special Issue Microbial Biosensors for Environmental Monitoring)

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Schematic diagram showing the structure of major phage families: (A) Myoviridae (e.g., T4); (B) filamentous Inoviridae (e.g., M13); (C) long and noncontractile Siphoviridae (e.g., λ phage); (D) Leviviridae; and (E) short Podoviridae (e.g., T7). Full article ">Figure 2
Schematic diagram showing the various intracellular cytoplasmic factors (biomarkers) released following phage infection. Abbr.: AK, adenosine kinase; ATP, adenosine triphosphate. Full article ">Figure 3
Strategies used for immobilization of phages on biosensor platforms. Full article ">Figure 4
Schematic diagram illustrating the working principle of a surface plasmon resonance sensor (SPR) using bacteriophages. Full article ">Figure 5
Schematic illustration of phage-based impedimetric biosensor, showing steps involved in phage immobilization and target bacteria detection: (A) surface modification of gold electrode using chemical linker (e.g., cysteamine); (B) cross-linker/enhancement using 1,4 dithiocyanate (PDICT); (C) immobilization of phages and treatment with ethanolamine to block nonspecific binding; (D) capture of target bacteria; and (E) impedance measurement (detection of target pathogen). Full article ">Figure 6
Schematic diagram elucidating the detection principle of the magnetoelastic phage sensor platform. Full article ">

13 pages, 4305 KiB

Open AccessArticle

A Paper-Based Electrochemical Sensor Based on PtNP/COF_TFPB−DHzDS@rGO for Sensitive Detection of Furazolidone

by Rongfang Chen, Xia Peng, Yonghai Song and Yan Du

Biosensors 2022, 12(10), 904; https://doi.org/10.3390/bios12100904 - 21 Oct 2022

Cited by 11 | Viewed by 2021

Abstract

Herein, a paper-based electrochemical sensor based on PtNP/COF_TFPB−DHzDS@rGO was developed for the sensitive detection of furazolidone. A cluster-like covalent organic framework (COF_TFPB−DHzDS) was successfully grown on the surface of amino-functional reduced graphene oxide (rGO-NH₂) to avoid serious [...] Read more.

Herein, a paper-based electrochemical sensor based on PtNP/COF_TFPB−DHzDS@rGO was developed for the sensitive detection of furazolidone. A cluster-like covalent organic framework (COF_TFPB−DHzDS) was successfully grown on the surface of amino-functional reduced graphene oxide (rGO-NH₂) to avoid serious self-aggregation, which was further loaded with platinum nanoparticles (PtNPs) with high catalytic activity as nanozyme to obtain PtNP/COF_TFPB−DHzDS@rGO nanocomposites. The morphology of PtNP/COF_TFPB−DHzDS@rGO nanocomposites was characterized, and the results showed that the smooth rGO surface became extremely rough after the modification of COF_TFPB−DHzDS. Meanwhile, ultra-small PtNPs with sizes of around 1 nm were precisely anchored on COF_TFPB−DHzDS to maintain their excellent catalytic activity. The conventional electrodes were used to detect furazolidone and showed a detection limit as low as 5 nM and a linear range from 15 nM to 110 μM. In contrast, the detection limit for the paper-based electrode was 0.23 μM, and the linear range was 0.69–110 μM. The results showed that the paper-based electrode can be used to detect furazolidone. This sensor is a potential candidate for the detection of furazolidone residue in human serum and fish samples. Full article

(This article belongs to the Special Issue Paper-Based Biosensors)

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10 pages, 2428 KiB

Open AccessArticle

Probing Subcellular Iron Availability with Genetically Encoded Nitric Oxide Biosensors

by Gulsah Sevimli, Amy E. Alston, Felix Funk, Beat Flühmann, Roland Malli, Wolfgang F. Graier and Emrah Eroglu

Biosensors 2022, 12(10), 903; https://doi.org/10.3390/bios12100903 - 21 Oct 2022

Cited by 3 | Viewed by 3775

Abstract

Cellular iron supply is required for various biochemical processes. Measuring bioavailable iron in cells aids in obtaining a better understanding of its biochemical activities but is technically challenging. Existing techniques have several constraints that make precise localization difficult, and the lack of a [...] Read more.

Cellular iron supply is required for various biochemical processes. Measuring bioavailable iron in cells aids in obtaining a better understanding of its biochemical activities but is technically challenging. Existing techniques have several constraints that make precise localization difficult, and the lack of a functional readout makes it unclear whether the tested labile iron is available for metalloproteins. Here, we use geNOps; a ferrous iron-dependent genetically encoded fluorescent nitric oxide (NO) biosensor, to measure available iron in cellular locales. We exploited the nitrosylation-dependent fluorescence quenching of geNOps as a direct readout for cellular iron absorption, distribution, and availability. Our findings show that, in addition to ferrous iron salts, the complex of iron (III) with N,N’-bis (2-hydroxybenzyl)ethylenediamine-N,N’-diacetic acid (HBED) can activate the iron (II)-dependent NO probe within intact cells. Cell treatment for only 20 min with iron sucrose was also sufficient to activate the biosensor in the cytosol and mitochondria significantly; however, ferric carboxymaltose failed to functionalize the probe, even after 2 h of cell treatment. Our findings show that the geNOps approach detects available iron (II) in cultured cells and can be applied to assay functional iron (II) at the (sub)cellular level. Full article

(This article belongs to the Special Issue Genetically Encoded Biosensors for Biomedical Applications)

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NO biosensor reports labile iron (II) in a concentration-dependent manner. (A) The cartoon shows iron (II) dependency of the NO biosensor geNOps. If iron salts are provided to cells, only ferrous iron can enter the cell cytosol through DMT1 channels but not ferric iron. Non-heme iron consisting of geNOps can sense NO in an iron (II)-concentration-dependent manner. (B) Average curves show real-time NO signals in response to 10 μM NOC-7 in HEK293T cells expressing O-geNOps. Cells have been treated with equimolar concentrations of FeSO4 and Vitamin C, respectively, for 20 min before imaging experiments: 500 μM (black curve, n = 3/60), 300 μM (dark grey curve, n = 3/54), 100 μM (green curve, n = 3/56), 30 μM (blue curve, n = 3/42), and control no treatment (light grey curve, n = 3/73). (C) Bars represent the statistical analysis of iron (II) dependent geNOps responses shown in panel (B). All values are given as ±SD, and Dunnet’s multiple comparison test was applied. ** 0 vs. 30 um, Mean Difference (Diff): −5.525, q = 5.182, 95% Confidential Interval (CI) of Diff: −8.607 to −2.443; *** 0 vs. 100 um; Mean Diff: −9.870; q = 9.257, 95% CI of Diff: −12.95 to −6.79; *** 0 vs. 300 um; Mean Diff: −11.400; q = 10.69, 95% CI of Diff: −14.48 to −8.32; *** 0 vs. 500 um; Mean Diff: −13.800; q = 12.94, 95% CI of Diff: −16.88 to −10.71. Full article ">Figure 2
Evaluation of the ferric iron chelator HBED and its effectiveness in different cultured cells to activate geNOps. (A) Representative wide-field images show immortalized endothelial cells (Ea.hy926), (B) human embryonic kidney cells (HEK293T), and (C) cervical cancer cells (HeLa) expressing cytosolic O-geNOps. Lower Panels: Average curves show NO responses of cells in response to 10 μM NOC-7 that have been treated with equimolar concentrations of HBED and Vitamin C, 1 mM, respectively, for 20 min before imaging experiments. The left panel shows Ea.hy926 cells (control grey curve, n = 3/60; HBED-treated, red curve, n = 3/74), middle panel HEK293T cells (control grey curve, n = 3/54; HBED-treated, red curve, n = 3/66) and the right panel shows HeLa cells (control grey curve, n = 3/29; HBED-treated, red curve, n = 3/18). All values are given as mean ± SD, and Student’s t-test was applied to compare maximum amplitudes between HBED-treated cells and control cells. (A) *** p = 0.0003, (B) ** p = 0.0081, (C) ** p = 0.0014. Full article ">Figure 3
Evaluation of the effectiveness of IS and FCM in cultured Eahy.926 cells to activate geNOps. (A) The upper panel shows representative real-time traces of intracellular NO signals in response to 10 μM NOC-7 reflecting the labile iron pool in Ea.hy926 cells upon treatment with IS (red curve) or FCM (orange curve) vs. control cells (grey curves). Cells were pretreated with 500 μg iron/mL with the respective drug for 20 min before the imaging experiment. The lower panel shows statistical analysis. Control (grey curve, n = 3/46), FCM (orange curve, n = 3/47), and IS (red curve, n = 3/55). Panel (B) shows the same experimental setup as in panel (A), with the difference that cell pretreatment with IS and FCM was extended to 2 h. Control (grey curve, n = 3/29), FCM (orange curve, n = 3/28), and IS (red curve, n = 3/32). All values are given as mean ± SD, and Dunnet’s multiple comparison test was applied. (A) *** p = 0.0002, (B) *** p = 0.0001. Full article ">Figure 4
Assessing iron (II) levels in subcellular locales upon IS treatment. (A) Representative wide-field images show HeLa cells stably expressing O-geNOps-NES (orange) transiently transfected with mitochondria-targeted C-geNOps (Mito-C-geNOp, cyan). (B) Real-time traces of intracellular NO signals in response to 10 μM NOC-7 in the cell cytosol (red curve and bar, co-imaged with O-geNOps, n = 3/18) or mitochondria (black curve and bar, co-imaged with C-geNOps, n = 3/18). All values are given as mean ± SD, and Student’s t-test was applied to compare maximum amplitudes between mitochondria and cytosolic NO signals. Full article ">

12 pages, 2796 KiB

Open AccessArticle

Glycated Hemoglobin Electrochemical Immunosensor Based on Screen-Printed Electrode

by Yuliang Zhao, Hongyu Zhang, Yang Li, Xiaoai Wang, Liang Zhao, Jianghong Xu, Zhikun Zhan, Guanglie Zhang and Wen Jung Li

Biosensors 2022, 12(10), 902; https://doi.org/10.3390/bios12100902 - 21 Oct 2022

Cited by 2 | Viewed by 2895

Abstract

An electrochemical HbA1c sensor with high sensitivity and good specificity is proposed based on the electrochemical immune principle. The reproducibility and conductivity of the electrode are improved by depositing gold nanoparticles (AuNPs) on the surface of the screen-printed electrode (SPE). The HbA1c antibodies [...] Read more.

An electrochemical HbA1c sensor with high sensitivity and good specificity is proposed based on the electrochemical immune principle. The reproducibility and conductivity of the electrode are improved by depositing gold nanoparticles (AuNPs) on the surface of the screen-printed electrode (SPE). The HbA1c antibodies are immobilized on the surface of the modified electrode by adsorption to capture the HbA1c in the sample. The hindering effect of HbA1c on the electrode transfer reaction was exploited as the HbA1c detection mechanism. The electrode’s properties were characterized by electrochemical impedance spectroscopy (EIS), and the measurement properties of the electrode were analyzed using differential pulse voltammetry (DPV) and cyclic voltammetry (CV). The experimental results show that the peak current signal of the electrochemical immunosensor produced a linear response to HbA1c in the concentration range of 20–200 μg/mL, a linear relationship coefficient of 0.9812, a detection limit of 15.5 µg/mL, and a sensitivity of 0.0938 µA/µg·mL⁻¹. The sensor delivered satisfactory repeatability, stability, and anti-interference performance. Due to its small size, high sensitivity, and wide linear detection range, it is expected to play a significant role in managing diabetes at home. Full article

(This article belongs to the Special Issue Biosensors for Bioanalytical and Healthcare Applications)

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(A) Dimensions of the SPE. (B) Electrodeposition of SPE in the mixture of 1 mM HAuCl4 and 10 mM K2SO4. (C) Anti-HbA1c incubation and capture HbA1c. (D) AuNPs/anti-HbA1c/HbA1c electrode for K3 [Fe(CN)6] testing. Full article ">Figure 2
Schematic diagram of the proposed electrochemical HbA1c immunosensor. Full article ">Figure 3
(A) CV response of SPEs before and after AuNPs modification. (B) DPV response of bare SPE, AuNPs SPE, AuNPs/anti-HbA1c SPE and AuNPs/anti-HbA1c/HbA1c SPE. (C) Complex impedance characteristics of electrodes in different states. (D) Charge-transfer resistance of electrodes in different states. Full article ">Figure 4
(A) SEM image of the SPE (2000 times). (B) SEM image of the SPE after AuNPs modification (2000 times). (C) SEM image of the SPE (8000 times). (D) SEM image of the SPE after AuNPs modification (8000 times). (E) EDX spectrum of the bare electrode. (F) EDX spectrum of the AuNPs-modified electrode. Full article ">Figure 5
Measurement curves and linear fitting diagram of the modified working electrode for different concentrations of HbA1c. (A) DPV measurement curves of the modified working electrode for different concentrations of HbA1c. (B) Linear fitting diagram of DPV peak current curves. (C) CV measurement curves of the modified working electrode for different concentrations of HbA1c. (D) Linear fitting diagram of CV current curves. Full article ">Figure 6
(A) Repeatability measurement: current of the immune electrodes to HbA1c of 10 μg/mL, 40 μg/mL, 100 μg/mL, and 150 μg/mL (insert: peak current comparison). (B) Specificity measurement: current of the immune electrodes to HbA1c, BSA, GLU, FRU, and VC. (C) Long-term measurement: 0 h, 24 h, 72 h. (D) Repeated experiments at 72 h. Full article ">

33 pages, 3655 KiB

Open AccessSystematic Review

Image Quality Improvement Techniques and Assessment Adequacy in Clinical Optoacoustic Imaging: A Systematic Review

by Ioannis Dimaridis, Patmaa Sridharan, Vasilis Ntziachristos, Angelos Karlas and Leontios Hadjileontiadis

Biosensors 2022, 12(10), 901; https://doi.org/10.3390/bios12100901 - 20 Oct 2022

Cited by 6 | Viewed by 3108

Abstract

Optoacoustic imaging relies on the detection of optically induced acoustic waves to offer new possibilities in morphological and functional imaging. As the modality matures towards clinical application, research efforts aim to address multifactorial limitations that negatively impact the resulting image quality. In an [...] Read more.

Optoacoustic imaging relies on the detection of optically induced acoustic waves to offer new possibilities in morphological and functional imaging. As the modality matures towards clinical application, research efforts aim to address multifactorial limitations that negatively impact the resulting image quality. In an endeavor to obtain a clear view on the limitations and their effects, as well as the status of this progressive refinement process, we conduct an extensive search for optoacoustic image quality improvement approaches that have been evaluated with humans in vivo, thus focusing on clinically relevant outcomes. We query six databases (PubMed, Scopus, Web of Science, IEEE Xplore, ACM Digital Library, and Google Scholar) for articles published from 1 January 2010 to 31 October 2021, and identify 45 relevant research works through a systematic screening process. We review the identified approaches, describing their primary objectives, targeted limitations, and key technical implementation details. Moreover, considering comprehensive and objective quality assessment as an essential prerequisite for the adoption of such approaches in clinical practice, we subject 36 of the 45 papers to a further in-depth analysis of the reported quality evaluation procedures, and elicit a set of criteria with the intent to capture key evaluation aspects. Through a comparative criteria-wise rating process, we seek research efforts that exhibit excellence in quality assessment of their proposed methods, and discuss features that distinguish them from works with similar objectives. Additionally, informed by the rating results, we highlight areas with improvement potential, and extract recommendations for designing quality assessment pipelines capable of providing rich evidence. Full article

(This article belongs to the Special Issue Optical Imaging and Biophotonic Sensors (OIBS))

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14 pages, 3431 KiB

Open AccessArticle

A Closed-Loop Approach to Fight Coronavirus: Early Detection and Subsequent Treatment

by Guoguang Rong, Yuqiao Zheng, Xi Yang, Kangjian Bao, Fen Xia, Huihui Ren, Sumin Bian, Lan Li, Bowen Zhu and Mohamad Sawan

Biosensors 2022, 12(10), 900; https://doi.org/10.3390/bios12100900 - 20 Oct 2022

Cited by 3 | Viewed by 2462

Abstract

The recent COVID-19 pandemic has caused tremendous damage to the social economy and people’s health. Some major issues fighting COVID-19 include early and accurate diagnosis and the shortage of ventilator machines for critical patients. In this manuscript, we describe a novel solution to [...] Read more.

The recent COVID-19 pandemic has caused tremendous damage to the social economy and people’s health. Some major issues fighting COVID-19 include early and accurate diagnosis and the shortage of ventilator machines for critical patients. In this manuscript, we describe a novel solution to deal with COVID-19: portable biosensing and wearable photoacoustic imaging for early and accurate diagnosis of infection and magnetic neuromodulation or minimally invasive electrical stimulation to replace traditional ventilation. The solution is a closed-loop system in that the three modules are integrated together and form a loop to cover all-phase strategies for fighting COVID-19. The proposed technique can guarantee ubiquitous and onsite detection, and an electrical hypoglossal stimulator can be more effective in helping severe patients and reducing complications caused by ventilators. Full article

(This article belongs to the Special Issue Current Accuracy and Advances in Wearable Sensors and Biosensors for Physiological Signals Measurement)

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13 pages, 3417 KiB

Open AccessArticle

A Novel Paper-Based Electrochemical Biosensor Based on N,O-Rich Covalent Organic Frameworks for Carbaryl Detection

by Yawen Xiao, Na Wu, Li Wang and Lili Chen

Biosensors 2022, 12(10), 899; https://doi.org/10.3390/bios12100899 - 20 Oct 2022

Cited by 10 | Viewed by 2260

Abstract

A new N,O-rich covalent organic framework (COF_DHNDA-BTH) was synthesized by an amine-aldehyde condensation reaction between 2,6-dialdehyde-1,5-dihydroxynaphthalene (DHNDA) and 1,3,5-phenyltriformylhydrazine (BTH) for carbaryl detection. The free NH, OH, and C=O groups of COF_DHNDA-BTH not only covalently couples with acetylcholinesterase (AChE) into [...] Read more.

A new N,O-rich covalent organic framework (COF_DHNDA-BTH) was synthesized by an amine-aldehyde condensation reaction between 2,6-dialdehyde-1,5-dihydroxynaphthalene (DHNDA) and 1,3,5-phenyltriformylhydrazine (BTH) for carbaryl detection. The free NH, OH, and C=O groups of COF_DHNDA-BTH not only covalently couples with acetylcholinesterase (AChE) into the pores of COF_DHNDA-BTH, but also greatly improves the catalytic activity of AChE in the constrained environment of COF_DHNDA-BTH’s pore. Under the catalysis of AChE, the acetylthiocholine (ATCl) was decomposed into positively charged thiocholine (TCl), which was captured on the COF_DHNDA-BTH modified electrode. The positive charges of TCl can attract anionic probe [Fe(CN)₆]^3−/4− on the COF_DHNDA-BTH-modified electrode to show a good oxidation peak at 0.25 V (versus a saturated calomel electrode). The carbaryl detection can inhibit the activity of AChE, resulting in the decrease in the oxidation peak. Therefore, a turn-off electrochemical carbaryl biosensor based on a flexible carbon paper electrode loaded with COF_DHNDA-BTH and AChE was constructed using the oxidation peak of an anionic probe [Fe(CN)₆]^3−/4− as the detection signal. The detection limit was 0.16 μM (S/N = 3), and the linear range was 0.48~35.0 μM. The sensor has good selectivity, repeatability, and stability, and has a good application prospect in pesticide detection. Full article

(This article belongs to the Special Issue Paper-Based Biosensors)

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(a) SEM image of COFDHNDA-BTH. (b) TEM image of COFDHNDA-BTH. (c) FTIR spectra of DHNDA, BTH, and COFDHNDA-BTH. (d) Experimental and refined XRD pattern as well as the difference. Full article ">Figure 2
(a) Low-resolution and (b) high-resolution SEM image of commercial carbon paper. Full article ">Figure 3
(a) CVs and (b) EIS of GCE (curve a), COFDHNDA-BTH/GCE (curve b), and AChE/COFDHNDA-BTH/GCE (curve c) in 0.1 M KCl with 5.0 mM [Fe(CN)6]3−/4−. Full article ">Figure 4
(a) Effect of COFDHNDA-BTH dosage on AChE/COFDHNDA-BTH/GCE on peak current density of 5.0 mM [Fe(CN)6]3−/4−. (b) Plot of inhibition rate versus incubation time. (c) Plot of peak current density versus AChE concentration. (d) Relationship between concentration of ATCl and peak current density in 0.1 M KCl with 5.0 mM [Fe(CN)6]3−/4−. Full article ">Figure 5
(a) CVs and (c) EIS (inset is its equivalent circuit) of AChE/COFDHNDA-BTH/GCE in 0.1 M KCl + 5.0 mM [Fe(CN)6]3−/4− with different concentrations of carbaryl. (b,d) Corresponding linear relationship curves. Full article ">Figure 6
(a) CVs of AChE/COFDHNDA-BTH/portable paper-based electrode in 0.1 M KCl + 5.0 mM [Fe(CN)6]3−/4− with carbaryl different concentrations. (b) Corresponding linear relationship curve. Full article ">Figure 7
(a) Selectivity test of electrochemical carbaryl biosensor. (b) Current response histogram of electrochemical carbaryl biosensor measured for 30 consecutive days of carbaryl. (c) Current response histogram of six AChE/COFDHNDA-BTH/GCE to detect carbaryl. Full article ">Scheme 1
Schematic diagram of preparation process of COFDHNDA-BTH and detection principle of electrochemical sensor based on AChE/COFDHNDA-BTH/GCE. Full article ">Scheme 2
Preparation process of paper-based electrode and the picture of obtained paper-based electrode. Full article ">

25 pages, 2733 KiB

Open AccessReview

Advances in Biosensing Technologies for Diagnosis of COVID-19

by Sulaiman Alsalameh, Khalid Alnajjar, Tariq Makhzoum, Noor Al Eman, Ismail Shakir, Tanveer Ahmad Mir, Khaled Alkattan, Raja Chinnappan and Ahmed Yaqinuddin

Biosensors 2022, 12(10), 898; https://doi.org/10.3390/bios12100898 - 20 Oct 2022

Cited by 14 | Viewed by 3773

Abstract

The COVID-19 pandemic has severely impacted normal human life worldwide. Due to its rapid community spread and high mortality statistics, the development of prompt diagnostic tests for a massive number of samples is essential. Currently used traditional methods are often expensive, time-consuming, laboratory-based, [...] Read more.

The COVID-19 pandemic has severely impacted normal human life worldwide. Due to its rapid community spread and high mortality statistics, the development of prompt diagnostic tests for a massive number of samples is essential. Currently used traditional methods are often expensive, time-consuming, laboratory-based, and unable to handle a large number of specimens in resource-limited settings. Because of its high contagiousness, efficient identification of SARS-CoV-2 carriers is crucial. As the advantages of adopting biosensors for efficient diagnosis of COVID-19 increase, this narrative review summarizes the recent advances and the respective reasons to consider applying biosensors. Biosensors are the most sensitive, specific, rapid, user-friendly tools having the potential to deliver point-of-care diagnostics beyond traditional standards. This review provides a brief introduction to conventional methods used for COVID-19 diagnosis and summarizes their advantages and disadvantages. It also discusses the pathogenesis of COVID-19, potential diagnostic biomarkers, and rapid diagnosis using biosensor technology. The current advancements in biosensing technologies, from academic research to commercial achievements, have been emphasized in recent publications. We covered a wide range of topics, including biomarker detection, viral genomes, viral proteins, immune responses to infection, and other potential proinflammatory biomolecules. Major challenges and prospects for future application in point-of-care settings are also highlighted. Full article

(This article belongs to the Special Issue Potentials and Challenges for Detecting COVID-19 by Novel Biosensing Systems)

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Figure 1
SARS-CoV-2 diagnosis by nucleic acid amplification method, qRT-PCR. (1,2). Nasopharyngeal swabs were taken from the patients. (3). RNA extracted/purified by RNA purification kit. (4). Extracted RNA is reverse transcribed to complementary DNA and amplification using the target-specific primers. (5). Quantitative real-time PCR (qRT-PCR) to identify the positive samples. Conducted to identify positive samples in real-time from the fluorescence of the dsDNA intercalating dyes such as SYBR green. Full article ">Figure 2
Schematic diagram and operational principle of biosensors. The sample is introduced to the biosensor; the bioreceptor interacts with the target molecule. The transducer coupled with the receptor transfer the respective signal to the amplifier, then the amplified signal is converted into readable signals. Full article ">Figure 3
Schematic representation of various genomic parts and their organization in the SARS-CoV-2 viral particle. Full article ">Figure 4
Schematic representation of loop-mediated isothermal amplification of SARS-CoV-2 RNA amplification. Full article ">Figure 5
(a) Pictorial representation of lateral flow immunoassay working principle. (b) The assay setup in the commercial test pad and (c) Interpretation of assay results positive/negative and the stability of the testing pad. Full article ">

12 pages, 2809 KiB

Open AccessArticle

A High-Performance Self-Supporting Electrochemical Biosensor to Detect Aflatoxin B1

by Yunfei Zhang, Tingting Lin, Yi Shen and Hongying Li

Biosensors 2022, 12(10), 897; https://doi.org/10.3390/bios12100897 - 20 Oct 2022

Cited by 9 | Viewed by 2473

Abstract

High-performance electrochemical biosensors for the rapid detection of aflatoxin B1 (AFB₁) are urgently required in the food industry. Herein, a multi-scaled electrochemical biosensor was fabricated by assembling carboxylated polystyrene nanospheres, an aptamer and horseradish peroxidase into a free-standing carbon nanofiber/carbon felt [...] Read more.

High-performance electrochemical biosensors for the rapid detection of aflatoxin B1 (AFB₁) are urgently required in the food industry. Herein, a multi-scaled electrochemical biosensor was fabricated by assembling carboxylated polystyrene nanospheres, an aptamer and horseradish peroxidase into a free-standing carbon nanofiber/carbon felt support. The resulting electrochemical biosensor possessed an exceptional performance, owing to the unique structures as well as the synergistic effects of the components. The 3D porous carbon nanofiber/carbon felt support served as an ideal substrate, owing to the excellent conductivity and facile diffusion of the reactants. The integration of carboxylated polystyrene nanospheres with horseradish peroxidase was employed as a signal amplification probe to enhance the electrochemical responses via catalyzing the decomposition of hydrogen peroxide. With the aid of the aptamer, the prepared sensors could quantitatively detect AFB₁ in wine and soy sauce samples via differential pulse voltammetry. The recovery rates of AFB₁ in the samples were between 87.53% and 106.71%. The limit of detection of the biosensors was 0.016 pg mL⁻¹. The electrochemical biosensors also had excellent sensitivity, reproducibility, specificity and stability. The synthetic strategy reported in this work could pave a new route to fabricate high-performance electrochemical biosensors for the detection of mycotoxins. Full article

(This article belongs to the Special Issue Role of Electrochemical Biosensors within Sustainable Food Chains and Food Safety)

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Digital photos of the hydrophilicity of the CF materials before and after thermal treatment. (a) Activated CF; (b) pristine CF. (c) CVs of the CF (black line) and activated CF (red line) were recorded in 1 mM [Fe(CN)6]3−/4− with a scan rate of 10 mV s−1. Full article ">Figure 2
FESEM micrographs of Ni-Cu oxalate-decorated CF (a,b) and SSE (c,d) at different scales. Full article ">Figure 3
(a) CVs of the SSE (black line) and Au/SSE (red line) electrodes recorded in 0.1 M NaOH with a scan rate of 10 mV s−1. (b) CVs of the as-prepared electrodes recorded in 1 mM [Fe(CN)6]3− with a scan rate of 10 mV s−1. Full article ">Figure 4
(a) Ip response of the biosensor to different concentrations of AFB1 in a large concentration range of 0~5000 pg mL−1. DPV responses of the biosensor recorded in 10 mM H2O2 with varying concentrations of AFB1 (b) and corresponding calibration curves of the biosensor for the detection of AFB1 (c). Error bars were obtained from three independent measurements. (d) I-t curve of the biosensor recorded in varying H2O2 concentrations. Full article ">Figure 5
(a) Reproducibility of six electrode samples (S1–S6). (b) Stability of an as-prepared electrode. Error bars shown were obtained from three independent measurements. Full article ">Figure 6
(a) Recovery rates of the developed biosensors for the detection of AFB1 and the mixture of AFB1 and OTA. Error bars were obtained from three independent measurements. (b) Selectivity test of the biosensor toward H2O2 by interference with Na+, K+, Mg2+, AA, CA, starch and G. Full article ">Scheme 1
Stepwise illustration of fabrication procedure of the electrochemical biosensor based on the self-supported electrode. Full article ">

11 pages, 1426 KiB

Open AccessArticle

A Lateral Flow Device for Point-of-Care Detection of Doxorubicin

by Tania Pomili, Francesca Gatto and Pier Paolo Pompa

Biosensors 2022, 12(10), 896; https://doi.org/10.3390/bios12100896 - 19 Oct 2022

Cited by 4 | Viewed by 2076

Abstract

A simple, rapid, and sensitive point-of-care (POC) device for the on-site detection of doxorubicin was developed. The proposed method relies on the naked-eye detection of the intrinsic fluorescence of the drug in a lateral flow device (LFD) configuration, exploiting the biological recognition of [...] Read more.

A simple, rapid, and sensitive point-of-care (POC) device for the on-site detection of doxorubicin was developed. The proposed method relies on the naked-eye detection of the intrinsic fluorescence of the drug in a lateral flow device (LFD) configuration, exploiting the biological recognition of DNA probes and avoiding the use of expensive antibodies and sophisticated instrumentations. The POC assay does not require any pre-treatment or purification step and provides an immediate visual readout, achieving a limit of detection as low as ca. 1 ng doxorubicin, outperforming several laboratory-based instrumental techniques. The POC method was proven useful for the detection of trace amounts of the drug both in the case of water solutions (to simulate surface contaminations) and in urine samples, opening promising perspectives for routine monitoring of doxorubicin, with potential benefit to healthcare workers and personalized chemotherapies. Full article

(This article belongs to the Special Issue Biosensing for Point-of-Care Diagnostics)

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Schematic illustration of the LFD for the assessment of doxorubicin contamination on surfaces and in urine. The device is composed of a running pad made of positively charged nylon and an absorbent pad, both laminated on the backing card and partially overlapped (2 mm). The test zone is realized by dropping 0.5 µL of the DNA solution onto the nylon pad. The test samples are deposited on the lateral side of the running pad and, flowing through the membrane, they reach the recognition element on the test zone. When doxorubicin molecules are present in the test sample, they intercalate with the immobilized DNA probes, giving an intense fluorescence, detectable by the naked eye, when excited by a UV lamp. In the case of non-contaminated samples, no intercalation occurs and, hence, no fluorescence is visualized. Full article ">Figure 2
(A) Representative photograph of the proposed devices tested with decreasing doxorubicin amounts, ranging from 160 to 0 ng, as reported in the upper part of the image (160, 80, 40, 16, 8, 4, 1.5, 0 ng, roughly corresponding to 10, 5, 2.5, 1, 0.5, 0.25, 0.1 µM); (B) analysis of the optical response of the device as a function of doxorubicin amounts (ΔG values were obtained subtracting the G coordinate of the sample from that of the blank (in RGB coordinates system)). G values were recorded in 9 different experiments. Full article ">Figure 3
Representative photograph of the LFD devices tested with real urine sample spiked with increasing doxorubicin amounts, as reported in the upper part of the image (240, 160, 80, 40, 16, 0 ng, roughly corresponding to 15, 10, 5, 2.5, 1, 0 µM). Full article ">

11 pages, 4584 KiB

Open AccessArticle

Effect of the Combination of Gold Nanoparticles and Polyelectrolyte Layers on SERS Measurements

by Antonello Nucera, Rossella Grillo, Carmen Rizzuto, Riccardo Cristoforo Barberi, Marco Castriota, Thomas Bürgi, Roberto Caputo and Giovanna Palermo

Biosensors 2022, 12(10), 895; https://doi.org/10.3390/bios12100895 - 19 Oct 2022

Cited by 4 | Viewed by 2059

Abstract

In this study, polyelectrolyte (PE) layers are deposited on substrates made by glass covered with an array of gold nanoparticles (GNPs). In particular, the samples studied have 0 PE layers (GGPE

_{0}

), 3 PE layers (GGPE

_{3}

), 11 PE layers (GGPE [...] Read more.

In this study, polyelectrolyte (PE) layers are deposited on substrates made by glass covered with an array of gold nanoparticles (GNPs). In particular, the samples studied have 0 PE layers (GGPE

_{0}

), 3 PE layers (GGPE

_{3}

), 11 PE layers (GGPE

_{11}

), and 21 PE layers (GGPE

_{21}

). All samples have been studied by micro-Raman spectroscopy. An acetic acid solution (10% v/v) has been used as a standard solution in order to investigate the SERS effect induced by different numbers of PE layers in each sample. The Surface Enhancement Raman Spectroscopy (SERS) effect correlating to the number of PE layers deposited on the samples has been shown. This effect is explained in terms of an increase in the interaction between the photon of the laser source and the plasmonic band of the GNPs due to a change of the permittivity of the surrounding medium around the GNPs. The trends of the ratios of the intensities of the Raman bands of the acetic acid solution (acetic acid and water molecules) on the band at 1098 cm

^{- 1}

ascribed to the substrates increase, and the number of PE layers increases. Full article

(This article belongs to the Special Issue High-Efficiency Surface-Enhanced Raman Scattering Biosensing)

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22 pages, 4735 KiB

Open AccessReview

Emerging Biosensing Technologies towards Early Sepsis Diagnosis and Management

by Andrea Bonini, Angela Gilda Carota, Noemi Poma, Federico Maria Vivaldi, Denise Biagini, Daria Bottai, Alessio Lenzi, Arianna Tavanti, Fabio Di Francesco and Tommaso Lomonaco

Biosensors 2022, 12(10), 894; https://doi.org/10.3390/bios12100894 - 18 Oct 2022

Cited by 8 | Viewed by 3270

Abstract

Sepsis is defined as a systemic inflammatory dysfunction strictly associated with infectious diseases, which represents an important health issue whose incidence is continuously increasing worldwide. Nowadays, sepsis is considered as one of the main causes of death that mainly affects critically ill patients [...] Read more.

Sepsis is defined as a systemic inflammatory dysfunction strictly associated with infectious diseases, which represents an important health issue whose incidence is continuously increasing worldwide. Nowadays, sepsis is considered as one of the main causes of death that mainly affects critically ill patients in clinical settings, with a higher prevalence in low-income countries. Currently, sepsis management still represents an important challenge, since the use of traditional techniques for the diagnosis does not provide a rapid response, which is crucial for an effective infection management. Biosensing systems represent a valid alternative due to their characteristics such as low cost, portability, low response time, ease of use and suitability for point of care/need applications. This review provides an overview of the infectious agents associated with the development of sepsis and the host biomarkers suitable for diagnosis and prognosis. Special focus is given to the new emerging biosensing technologies using electrochemical and optical transduction techniques for sepsis diagnosis and management. Full article

(This article belongs to the Special Issue Feature Review Papers for Biosensors)

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15 pages, 2789 KiB

Open AccessArticle

A Paper-Based Analytical Device Integrated with Smartphone: Fluorescent and Colorimetric Dual-Mode Detection of β-Glucosidase Activity

by Wei-Yi Zhang, Tao Tian, Li-Jing Peng, Hang-Yu Zhou, Hao Zhang, Hua Chen and Feng-Qing Yang

Biosensors 2022, 12(10), 893; https://doi.org/10.3390/bios12100893 - 18 Oct 2022

Cited by 15 | Viewed by 3012

Abstract

In this work, indoxyl-glucoside was used as the substrate to develop a cost-effective, paper-based analytical device for the fluorescent and colorimetric dual-mode detection of β-glucosidase activity through a smartphone. The β-glucosidase can hydrolyze the colorless substrate indoxyl-glucoside to release indoxyl, which will be [...] Read more.

In this work, indoxyl-glucoside was used as the substrate to develop a cost-effective, paper-based analytical device for the fluorescent and colorimetric dual-mode detection of β-glucosidase activity through a smartphone. The β-glucosidase can hydrolyze the colorless substrate indoxyl-glucoside to release indoxyl, which will be self-oxidized to generate green products in the presence of oxygen. Meanwhile, the green products emit bright blue-green fluorescence under ultraviolet–visible light irradiation at 365 nm. Fluorescent or colorimetric images were obtained by a smartphone, and the red-green-blue channels were analyzed by the Adobe Photoshop to quantify the β-glucosidase activity. Under the optimum conditions, the relative fluorescent and colorimetric signals have a good linear relationship with the activity of β-glucosidase, in the range of 0.01–1.00 U/mL and 0.25–5.00 U/mL, and the limits of detection are 0.005 U/mL and 0.0668 U/mL, respectively. The activities of β-glucosidase in a crude almond sample measured by the fluorescent and colorimetric methods were 23.62 ± 0.53 U/mL and 23.86 ± 0.25 U/mL, respectively. In addition, the spiked recoveries of normal human serum and crude almond samples were between 87.5% and 118.0%. In short, the paper-based device, combined with a smartphone, can provide a simple, environmentally friendly, and low-cost method for the fluorescent and colorimetric dual-mode detection of β-glucosidase activity. Full article

(This article belongs to the Special Issue Paper-Based Biosensors)

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Schematic illustration of fluorescent and colorimetric dual-mode detection of β-glucosidase, based on the paper-based device using indoxyl-glucoside as a substrate. Full article ">Figure 2
Structure diagram of homemade camera obscura (A) and paper-based device (B). Full article ">Figure 3
(A) Reaction mechanism of indoxyl-glucoside in the presence of β-glucosidase. (B) Fluorescent and colorimetric diagrams of paper-based device in the presence of different reagents: (a) pure filter paper, (b) indoxyl-glucoside, (c) β-glucosidase, (d) indoxyl-glucoside and β-glucosidase. Full article ">Figure 4
Intensity of RGB channels in fluorescent images irradiated by ultraviolet light at 365 nm of the paper-based device with different activity of β-glucosidase. Full article ">Figure 5
Effect of pH (A), temperature (B), indoxyl-glucoside concentration (C), and reaction time (D) on the fluorescent detection of β-glucosidase by the paper-based device, β-glucosidase = 1.0 U/mL. Inset: effect of temperature on the fluorescent detection of β-glucosidase by the paper-based device, β-glucosidase = 0.0 U/mL. Full article ">Figure 6
The relative fluorescent value of the paper-based device changed with the activity of β-glucosidase. Inset: calibration plot in the linear range of 0.01–1.00 U/mL. Photographs: fluorescent images of paper-based device at different β-glucosidase activity. Full article ">Figure 7
(A) Intensity of RGB channels in colorimetric images of the paper-based devices with different activity of β-glucosidase. (B) The relative colorimetric value of the paper-based device is changed with the activity of β-glucosidase. Inset: calibration plot in the linear range of 0.25–5.00 U/mL. Photographs: colorimetric images of paper-based device at different β-glucosidase activity. Full article ">Figure 8
Selectivity and interference study of the paper-based device for β-glucosidase detection: (A) fluorescence, (B) colorimetry. Full article ">

30 pages, 5471 KiB

Open AccessReview

Recent Advancements in Nanobiosensors: Current Trends, Challenges, Applications, and Future Scope

by Madhusudan B. Kulkarni, Narasimha H. Ayachit and Tejraj M. Aminabhavi

Biosensors 2022, 12(10), 892; https://doi.org/10.3390/bios12100892 - 18 Oct 2022

Cited by 50 | Viewed by 12315

Abstract

In recent years, there has been immense advancement in the development of nanobiosensors as these are a fundamental need of the hour that act as a potential candidate integrated with point-of-care-testing for several applications, such as healthcare, the environment, energy harvesting, electronics, and [...] Read more.

In recent years, there has been immense advancement in the development of nanobiosensors as these are a fundamental need of the hour that act as a potential candidate integrated with point-of-care-testing for several applications, such as healthcare, the environment, energy harvesting, electronics, and the food industry. Nanomaterials have an important part in efficiently sensing bioreceptors such as cells, enzymes, and antibodies to develop biosensors with high selectivity, peculiarity, and sensibility. It is virtually impossible in science and technology to perform any application without nanomaterials. Nanomaterials are distinguished from fine particles used for numerous applications as a result of being unique in properties such as electrical, thermal, chemical, optical, mechanical, and physical. The combination of nanostructured materials and biosensors is generally known as nanobiosensor technology. These miniaturized nanobiosensors are revolutionizing the healthcare domain for sensing, monitoring, and diagnosing pathogens, viruses, and bacteria. However, the conventional approach is time-consuming, expensive, laborious, and requires sophisticated instruments with skilled operators. Further, automating and integrating is quite a challenging process. Thus, there is a considerable demand for the development of nanobiosensors that can be used along with the POCT module for testing real samples. Additionally, with the advent of nano/biotechnology and the impact on designing portable ultrasensitive devices, it can be stated that it is probably one of the most capable ways of overcoming the aforementioned problems concerning the cumulative requirement for the development of a rapid, economical, and highly sensible device for analyzing applications within biomedical diagnostics, energy harvesting, the environment, food and water, agriculture, and the pharmaceutical industry. Full article

(This article belongs to the Special Issue Application of Nanomaterials for Biosensors)

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17 pages, 3746 KiB

Open AccessArticle

Detection of SARS-CoV-2 Neutralizing Antibodies in Vaccinated Pregnant Women and Neonates by Using a Lateral Flow Immunoassay Coupled with a Spectrum-Based Reader

by Wei-Chun Chen, Yen-Pin Lin, Chao-Min Cheng, Ching-Fen Shen, Chang-Wei Li, Yu-Kuo Wang, Ting-Ying Shih, Chitsung Hong, Ting-Chang Chang and Ching-Ju Shen

Biosensors 2022, 12(10), 891; https://doi.org/10.3390/bios12100891 - 18 Oct 2022

Cited by 3 | Viewed by 2629

Abstract

The focus of this study was to investigate the detection of neutralizing antibodies (Nabs) in maternal serum and cord blood as the targeted samples by employing a lateral flow immunoassay combined with a spectrum reader (LFI-SR) and the correlation of Nab protection against [...] Read more.

The focus of this study was to investigate the detection of neutralizing antibodies (Nabs) in maternal serum and cord blood as the targeted samples by employing a lateral flow immunoassay combined with a spectrum reader (LFI-SR) and the correlation of Nab protection against different types of SARS-CoV-2. We enrolled 20 pregnant women who were vaccinated with the Moderna (mRNA-1273) vaccine during pregnancy and collected 40 samples during delivery. We used an LFI-SR for the level of spike protein receptor binding domain antibody (SRBD IgG) as Nabs and examined the correlation of the SRBD IgG concentration and Nab inhibition rates (NabIR) via enzyme-linked immunosorbent assays (ELISA). The LFI-SR had high confidence for the SRBD IgG level (p < 0.0001). Better NabIR were found in wild-type SARS-CoV-2 (WT) compared to Delta-type (DT) and Omicron-type (OT). Women with two-dose vaccinations demonstrated greater NabIR than those with a single dose. The cut-off value of the SRBD IgG level by the LFI-SR for NabIR to DT (≥30%; ≥70%) was 60.15 and 150.21 ng/mL for mothers (both p = 0.005), and 156.31 (p = 0.011) and 230.20 ng/mL (p = 0.006) for babies, respectively. An additional vaccine booster may be considered for those mothers with SRBD IgG levels < 60.15 ng/mL, and close protection should be given for those neonates with SRBD IgG levels < 150.21 ng/mL, since there is no available vaccine for them. Full article

(This article belongs to the Special Issue Optical Biosensors for Health, Food and Environment (Bio)markers)

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17 pages, 6675 KiB

Open AccessReview

SARS-CoV-2-on-Chip for Long COVID Management

by Jayesh Cherusseri, Claire Mary Savio, Mohammad Khalid, Vishal Chaudhary, Arshid Numan, Sreekanth J. Varma, Amrutha Menon and Ajeet Kaushik

Biosensors 2022, 12(10), 890; https://doi.org/10.3390/bios12100890 - 18 Oct 2022

Cited by 20 | Viewed by 3897

Abstract

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has become a “wicked evil” in this century due to its extended progression and huge human mortalities. Although the diagnosis of SARS-CoV-2 viral infection is made simple and practical by employing reverse transcription polymerase chain reaction [...] Read more.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has become a “wicked evil” in this century due to its extended progression and huge human mortalities. Although the diagnosis of SARS-CoV-2 viral infection is made simple and practical by employing reverse transcription polymerase chain reaction (RT-PCR) investigation, the process is costly, complex, time-consuming, and requires experts for testing and the constraints of a laboratory. Therefore, these challenges have raised the paradigm of on-site portable biosensors on a single chip, which reduces human resources and enables remote access to minimize the overwhelming burden on the existing global healthcare sector. This article reviews the recent advancements in biosensors for long coronavirus disease (COVID) management using a multitude of devices, such as point-of-care biosensors and lab-on-chip biosensors. Furthermore, it details the shift in the paradigm of SARS-CoV-2-on-chip biosensors from the laboratory to on-site detection with intelligent and economical operation, representing near-future diagnostic technologies for public health emergency management. Full article

(This article belongs to the Special Issue Potentials and Challenges for Detecting COVID-19 by Novel Biosensing Systems)

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30 pages, 4893 KiB

Open AccessReview

Progress in Data Acquisition of Wearable Sensors

by Zixuan Liu, Jingjing Kong, Menglong Qu, Guangxin Zhao and Cheng Zhang

Biosensors 2022, 12(10), 889; https://doi.org/10.3390/bios12100889 - 18 Oct 2022

Cited by 8 | Viewed by 4193

Abstract

Wearable sensors have demonstrated wide applications from medical treatment, health monitoring to real-time tracking, human-machine interface, smart home, and motion capture because of the capability of in situ and online monitoring. Data acquisition is extremely important for wearable sensors, including modules of probes, [...] Read more.

Wearable sensors have demonstrated wide applications from medical treatment, health monitoring to real-time tracking, human-machine interface, smart home, and motion capture because of the capability of in situ and online monitoring. Data acquisition is extremely important for wearable sensors, including modules of probes, signal conditioning, and analog-to-digital conversion. However, signal conditioning, analog-to-digital conversion, and data transmission have received less attention than probes, especially flexible sensing materials, in research on wearable sensors. Here, as a supplement, this paper systematically reviews the recent progress of characteristics, applications, and optimizations of transistor amplifiers and typical filters in signal conditioning, and mainstream analog-to-digital conversion strategies. Moreover, possible research directions on the data acquisition of wearable sensors are discussed at the end of the paper. Full article

(This article belongs to the Section Intelligent Biosensors and Bio-Signal Processing)

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16 pages, 5058 KiB

Open AccessArticle

Kinetics of Drug Molecule Interactions with a Newly Developed Nano-Gold-Modified Spike Protein Electrochemical Receptor Sensor

by Dingqiang Lu, Danyang Liu, Xinqian Wang, Yujiao Liu, Yixuan Liu, Ruijuan Ren and Guangchang Pang

Biosensors 2022, 12(10), 888; https://doi.org/10.3390/bios12100888 - 17 Oct 2022

Cited by 2 | Viewed by 2138

Abstract

In March 2020, the World Health Organization (WHO) declared COVID-19 a pandemic, and the spike protein has been reported to be an important drug target for anti-COVID-19 treatment. As such, in this study, we successfully developed a novel electrochemical receptor biosensor by immobilizing [...] Read more.

In March 2020, the World Health Organization (WHO) declared COVID-19 a pandemic, and the spike protein has been reported to be an important drug target for anti-COVID-19 treatment. As such, in this study, we successfully developed a novel electrochemical receptor biosensor by immobilizing the SARS-CoV-2 spike protein and using AuNPs-HRP as an electrochemical signal amplification system. Moreover, the time-current method was used to quantify seven antiviral drug compounds, such as arbidol and chloroquine diphosphate. The results show that the spike protein and the drugs are linearly correlated within a certain concentration range and that the detection sensitivity of the sensor is extremely high. In the low concentration range of linear response, the kinetics of receptor–ligand interactions are similar to that of an enzymatic reaction. Among the investigated drug molecules, bromhexine exhibits the smallest Ka value, and thus, is most sensitively detected by the sensor. Hydroxychloroquine exhibits the largest Ka value. Molecular docking simulations of the spike protein with six small-molecule drugs show that residues of this protein, such as Asp, Trp, Asn, and Gln, form hydrogen bonds with the -OH or -NH₂ groups on the branched chains of small-molecule drugs. The electrochemical receptor biosensor can directly quantify the interaction between the spike protein and drugs such as abidor and hydroxychloroquine and perform kinetic studies with a limit of detection 3.3 × 10⁻²⁰ mol/L, which provides a new research method and idea for receptor–ligand interactions and pharmacodynamic evaluation. Full article

(This article belongs to the Special Issue Nanoengineering for Advanced Biosensors)

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Schematic illustration of the fabrication process of the spike protein receptor biosensor. Full article ">Figure 2
(a) Cyclic voltammetry characterization of spike protein receptor sensor electrode assembly modifications. (b) the impact of thionine on electrochemical properties characterized by cyclic voltammetry; curve 1 is the cyclic voltammogram of Thi-Chit/GCE and curve 2 is the cyclic voltammogram of Chit/GCE. The peak current increases gradually when thi is present, indicating that thi facilitates the transfer of electrons between the electrode and the substrate. Cyclic voltammetry was performed in 1 × 10−3 mol/L K3Fe(CN)6 (containing 0.20 mol/L KNO3) solution with a scanning potential range of −0.1 to 0.6 V and a scanning rate of 50 mV/s, using a three-electrode system; the prepared S protein receptor sensor was used as the working electrode, Ag/AgCl electrode as the reference electrode and platinum wire electrode as the counter electrode. Full article ">Figure 3
SEM of sensor assembly process: (a) GCE; (b) Thi-Chit/GCE; (c) AuNPs-HRP/Thi-Chit/GCE; (d) spike protein/AuNPs-HRP/Thi-Chit/GCE; (e) BSA/spike protein/AuNPs-HRP/Thi-Chit/GCE. Full article ">Figure 4
Rate of change of response current in the detection range (the concentration range of Shuanghuanglian oral liquid, arbidol, and lopinavir were 1 × 10−20 mol/L, ribavirin and chloroquine diphosphate were 1 × 10−19 mol/L, hydroxychloroquine was 1 × 10−14 mol/L, bromhexine was 1 × 10−21 mol/L, and KCl was 1 × 10−15 mol/L as control). Full article ">Figure 5
Variation of the rate of change of the response current as a function of drug concentration: (A) Shuanghuanglian oral liquid 10−20–10−18 mol/L; (B) abridol 10−20–10−18 mol/L; (C) chloroquine diphosphate 10−19–10−17 mol/L; (D) lopinavir 10−19–10−17 mol/L; (E) ribavirin 10−19–10−17 mol/L; (F) bromhexine 10−21–10−19 mol/L; and (G) hydroxychloroquine 10−14–10−12 mol/L; (H) KCl 10−15–10−13 mol/L as control. Full article ">Figure 6
Fitted response curves: (A) Shuanghuanglian oral liquid 10−20–10−18 mol/L; (B) abridol 10−20–10−18 mol/L; (C) chloroquine diphosphate 10−19–10−17 mol/L; (D) lopinavir 10−19–10−17 mol/L; (E) ribavirin 10−19–10−17 mol/L; (F) bromhexine 10−21–10−19 mol/L; and (G) hydroxychloroquine 10−14–10−12 mol/L (H) KCl 10−15–10−13 mol/L as control. Full article ">Figure 7
Double reciprocal plots of the fitted response curves of (A) Shuanghuanglian oral liquid 10−20–10−18 mol/L; (B) abridol 10−20–10−18 mol/L; (C) chloroquine diphosphate 10−19–10−17 mol/L; (D) lopinavir 10−19–10−17 mol/L; (E) ribavirin 10−19–10−17 mol/L; (F) bromhexine 10−21–10−19 mol/L; and (G) hydroxychloroquine 10−14–10−12 mol/L. Full article ">Figure 8
3D schematic diagram of the molecular docking simulation of the spike protein with (A) lopinavir, (B) chloroquine diphosphate, (C) abridol, (D) hydroxychloroquine, (E) ribavirin, and (F) bromhexine. Full article ">

10 pages, 3023 KiB

Open AccessFeature PaperArticle

A Sensitive Aptamer Fluorescence Anisotropy Sensor for Cd²⁺ Using Affinity-Enhanced Aptamers with Phosphorothioate Modification

by Hao Yu and Qiang Zhao

Biosensors 2022, 12(10), 887; https://doi.org/10.3390/bios12100887 - 17 Oct 2022

Cited by 8 | Viewed by 2519

Abstract

Rapid and sensitive detection of heavy metal cadmium ions (Cd²⁺) is of great significance to food safety and environmental monitoring, as Cd²⁺ contamination and exposure cause serious health risk. In this study we demonstrated an aptamer-based fluorescence anisotropy (FA) sensor [...] Read more.

Rapid and sensitive detection of heavy metal cadmium ions (Cd²⁺) is of great significance to food safety and environmental monitoring, as Cd²⁺ contamination and exposure cause serious health risk. In this study we demonstrated an aptamer-based fluorescence anisotropy (FA) sensor for Cd²⁺ with a single tetramethylrhodamine (TMR)-labeled 15-mer Cd²⁺ binding aptamer (CBA15), integrating the strengths of aptamers as affinity recognition elements for preparation, stability, and modification, and the advantages of FA for signaling in terms of sensitivity, simplicity, reproducibility, and high throughput. In this sensor, the Cd²⁺-binding-induced aptamer structure change provoked significant alteration of FA responses. To acquire better sensing performance, we further introduced single phosphorothioate (PS) modification of CBA15 at a specific phosphate backbone position, to enhance aptamer affinity by possible strong interaction between sulfur and Cd²⁺. The aptamer with PS modification at the third guanine (G) nucleotide (CBA15-G3S) had four times higher affinity than CBA15. Using as an aptamer probe CBA15-G3S with a TMR label at the 12th T, we achieved sensitive selective FA detection of Cd²⁺, with a detection limit of 6.1 nM Cd²⁺. This aptamer-based FA sensor works in a direct format for detection without need for labeling Cd²⁺, overcoming the limitations of traditional competitive immuno-FA assay using antibodies and fluorescently labeled Cd²⁺. This FA method enabled the detection of Cd²⁺ in real water samples, showing broad application potential. Full article

(This article belongs to the Special Issue Label-Free Biosensor)

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(A) Schematic diagram of fluorescence anisotropy sensor for Cd2+ using TMR-labeled aptamers. (B) The predicted secondary structure of the aptamer CBA15, with single TMR labeled on the 12th thymine base. Full article ">Figure 2
(A) FA responses of CBA15 with TMR labels at different sites (20 nM). (B) FA changes of TMR-labeled CBA15 caused by 500 nM Cd2+. Δr was obtained by subtracting the FA values of the blank sample from the FA values of 500 nM Cd2+. Full article ">Figure 3
FA changes (Δr) of different TMR-labeled aptamers upon binding with various concentrations of Cd2+. Δr was obtained by subtracting the FA values of blank samples from the FA values of various concentrations of Cd2+. Full article ">Figure 4
ITC analysis of aptamers (A) CBA15-G3S and (B) CBA15 with Cd2+. The top graph shows raw data for ITC titration, and the bottom graph displays the binding curve obtained by integrating the heats of each spike. The difference between PS modification and the phosphate (PO) group in the backbone of the aptamer is shown. Full article ">Figure 5
(A) Effects of NaCl concentration on FA responses of blank sample solution and the solution containing 1000 nM Cd2+ with 20 nM CBA15-G3S-T12-TMR. (B) The relationship between FA changes (Δr) caused by Cd2+ and NaCl concentration. Full article ">Figure 6
(A) FA detection of Cd2+ using CBA15-G3S-T12-TMR. (B) Selectivity test of the FA sensor using CBA15-G3S-T12-TMR for Cd2+ detection. A 20 nM aptamer probe was used, and the concentrations of tested metal ions were 1000 nM. Full article ">

13 pages, 3118 KiB

Open AccessArticle

Colorimetric Detection of Urease-Producing Microbes Using an Ammonia-Responsive Flexible Film Sensor

by Yunsoo Chang, Tae-Eon Park, Seung-Woo Lee and Eun-Hee Lee

Biosensors 2022, 12(10), 886; https://doi.org/10.3390/bios12100886 - 17 Oct 2022

Cited by 5 | Viewed by 3271

Abstract

Urease-producing (ureolytic) microbes have given rise to environmental and public health concerns because they are thought to contribute to emissions of ammonia and to be a virulence factor for infections. Therefore, it is highly important to have the ability to detect such microbes. [...] Read more.

Urease-producing (ureolytic) microbes have given rise to environmental and public health concerns because they are thought to contribute to emissions of ammonia and to be a virulence factor for infections. Therefore, it is highly important to have the ability to detect such microbes. In this study, a poly(dimethylsiloxane) (PDMS)-based colorimetric film sensor was employed for the detection of urease-producing microbes. The sensor was able to detect the enzyme activity of commercially available urease, as the color and absorbance spectrum of the sensor was observed to change upon being exposed to the reaction catalyzed by urease. The ratio of the absorbance of the sensor at 640 nm to that at 460 nm (A₆₄₀/A₄₆₀) was linearly proportional to the amount of urease present. The performance of the sensor was validated by the results of a sensitivity and selectivity analysis towards thirteen different bacterial strains. Based on the development of blue color of the sensor, the tested bacteria were classified as strongly positive, moderately positive, weakly positive, or negative urease producers. The response of the sensor to ureolytic bacteria was verified using the urease inhibitor phenyl phosphorodiamidate (PPDA). Additionally, the sensor achieved the selective detection of ureolytic bacteria even in the presence of non-ureolytic bacteria. In addition, a used sensor could be reverted to its original state by being subjected to simple aeration, and in this way the same sensor could be used at least five times for the detection of bacterial urease activity. Full article

(This article belongs to the Section Biosensors and Healthcare)

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Schematic diagram of the colorimetric detection of microbial urease activity using the designed film sensor. (a) Composition of the colorimetric film sensor. (b) Reaction mechanism of the enzymatically catalyzed hydrolysis of urea. (c) Schematic of the experimental procedure used for the detection of ureolytic bacteria. (d) Reversible changes in the color of the sensor upon its exposure to ammonia gas and subsequent aeration. Full article ">Figure 2
Detection of urease enzyme using the colorimetric film sensor. (a) Absorbance spectra and (b) A640/A460 values of sensors exposed to various units of urease. The dashed line depicts the A640/A460 value of the sensor not exposed to urease (0.00 U, negative control). Symbols and error bars indicate the mean and standard deviations of biological triplicates. Insets show photographs of the sensors exposed to the various units of urease. Full article ">Figure 3
Colorimetric detection of ureolytic activity in Klebsiella pneumoniae (K. pneumoniae). (a) Absorbance spectra and (b) A640/A460 values of the colorimetric film sensors exposed to K. pneumoniae for the indicated incubation times. Symbols and error bars indicate the mean and standard deviations of biological triplicates. Insets show photographs of film sensors at each incubation time. Full article ">Figure 4
(a–f) Colorimetric detection of ureolytic bacteria using the designed film sensor. The A640/A460 values of sensors exposed to indicated bacteria plotted against incubation duration. Insets show photographs of the sensors. The dashed lines each indicate the A640/A460 value of the sensor in the absence of inoculum (negative control). Symbols and error bars represent the mean and standard deviations of biological triplicates. Full article ">Figure 5
Verification of ureolytic activity in Klebsiella pneumoniae (K. pneumoniae) using a urease inhibitor, namely phenyl phosphorodiamidate (PPDA). The A640/A460 values and photographs (in insets showing colors) of film sensors in the absence and presence of PPDA are presented. Full article ">Figure 6
Colorimetric detection of urease activity of Klebsiella pneumoniae (K. pneumoniae) in the presence of non-ureolytic bacteria. The A640/A460 values and photographs of film sensors each acquired after an incubation duration of 10 h. A: Citrobacter koseri (C. koseri) + Escherichia coli (E. coli) + Klebsiella michiganensis (K. michiganensis) + Providencia alcalifaciens (P. alcalifaciens) (non-ureolytic bacteria only), B: K. pneumoniae only, C: K. pneumoniae + C. koseri, D: K. pneumoniae + E. coli, E: K. pneumoniae + K. michiganensis, F: K. pneumoniae + P. alcalifaciens, and G: K. pneumoniae + C. koseri + E. coli + K. michiganensis + P. alcalifaciens. Different lowercases indicate a statistical significance between the means of sample sets at a significance level (p-value) of 0.05. Full article ">Figure 7
Reusability of the colorimetric film sensor. The A640/A460 values and photographs (showing colors) of a sensor reused five times are presented. Full article ">

12 pages, 1971 KiB

Open AccessArticle

Graphene-Binding Peptide in Fusion with SARS-CoV-2 Antigen for Electrochemical Immunosensor Construction

by Beatriz A. Braz, Manuel Hospinal-Santiani, Gustavo Martins, Cristian S. Pinto, Aldo J. G. Zarbin, Breno C. B. Beirão, Vanete Thomaz-Soccol, Márcio F. Bergamini, Luiz H. Marcolino-Junior and Carlos R. Soccol

Biosensors 2022, 12(10), 885; https://doi.org/10.3390/bios12100885 - 17 Oct 2022

Cited by 17 | Viewed by 2530

Abstract

The development of immunosensors to detect antibodies or antigens has stood out in the face of traditional methods for diagnosing emerging diseases such as the one caused by the SARS-CoV-2 virus. The present study reports the construction of a simplified electrochemical immunosensor using [...] Read more.

The development of immunosensors to detect antibodies or antigens has stood out in the face of traditional methods for diagnosing emerging diseases such as the one caused by the SARS-CoV-2 virus. The present study reports the construction of a simplified electrochemical immunosensor using a graphene-binding peptide applied as a recognition site to detect SARS-CoV-2 antibodies. A screen-printed electrode was used for sensor preparation by adding a solution of peptide and reduced graphene oxide (rGO). The peptide-rGO suspension was characterized by scanning electron microscopy (SEM), Raman spectroscopy, and Fourier transform infrared spectroscopy (FT-IR). The electrochemical characterization (electrochemical impedance spectroscopy—EIS, cyclic voltammetry—CV and differential pulse voltammetry—DPV) was performed on the modified electrode. The immunosensor response is based on the decrease in the faradaic signal of an electrochemical probe resulting from immunocomplex formation. Using the best set of experimental conditions, the analytic curve obtained showed a good linear regression (r² = 0.913) and a limit of detection (LOD) of 0.77 μg mL⁻¹ for antibody detection. The CV and EIS results proved the efficiency of device assembly. The high selectivity of the platform, which can be attributed to the peptide, was demonstrated by the decrease in the current percentage for samples with antibody against the SARS-CoV-2 S protein and the increase in the other antibodies tested. Additionally, the DPV measurements showed a clearly distinguishable response in assays against human serum samples, with sera with a response above 95% being considered negative, whereas responses below this value were considered positive. The diagnostic platform developed with specific peptides is promising and has the potential for application in the diagnosis of other infections that lead to high antibody titers. Full article

(This article belongs to the Special Issue Recent Advances in the Screen-Printed Electrochemical (Bio)sensors)

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Schematic illustration of immunosensor step-by-step construction. Full article ">Figure 2
(a) SEM image, (b) FTIR spectra and (c) Raman spectra of rGO (black line) and mixture peptide + rGO (red line). Full article ">Figure 3
(a) DPVs obtained for each step of the immunosensor construction with peptide, rGO and BSA, with 1 mmol L−1 K3[Fe(CN)6] in PBS 0.1 mol L−1. (b) Summarized data obtained from probe current peak to each step of building up the sensor (n = 3, ±SD). Full article ">Figure 4
(a) Analytical curve obtained through probe current peak intensity vs. antibody concentration (n = 3, ±SD) on 0.1 mol L−1 PBS, pH 7.4. (b) Summarized DPV assays for negative human serum spiked with different AbS concentrations (n = 3, ± SD). Full article ">Figure 5
DPV data summarized for selectivity test against YFV antibodies, AbN SARS-CoV-2 and a mixture with AbS, YFV and AbN (n = 3, ± SD). Full article ">Figure 6
Summarized DPV data for assays with negative and positive human serum (n = 3, ± SD). Full article ">

14 pages, 3712 KiB

Open AccessArticle

Detecting the PEX Like Domain of Matrix Metalloproteinase-14 (MMP-14) with Therapeutic Conjugated CNTs

by D. Vieira, J. Barralet, E. J. Harvey and G. Merle

Biosensors 2022, 12(10), 884; https://doi.org/10.3390/bios12100884 - 17 Oct 2022

Cited by 1 | Viewed by 1993

Abstract

Matrix metalloproteinases (MMPs) are essential proteins acting directly in the breakdown of the extra cellular matrix and so in cancer invasion and metastasis. Given its impact on tumor angiogenesis, monitoring MMP-14 provides strategic insights on cancer severity and treatment. In this work, we [...] Read more.

Matrix metalloproteinases (MMPs) are essential proteins acting directly in the breakdown of the extra cellular matrix and so in cancer invasion and metastasis. Given its impact on tumor angiogenesis, monitoring MMP-14 provides strategic insights on cancer severity and treatment. In this work, we report a new approach to improve the electrochemical interaction of the MMP-14 with the electrode surface while preserving high specificity. This is based on the detection of the hemopexin (PEX) domain of MMP-14, which has a greater availability with a stable and low-cost commercial molecule, as a recognition element. This molecule, called NSC-405020, is specific of the PEX domain of MMP-14 within the binding pocket. Through the covalent grafting of the NSC-405020 molecule on carbon nanotubes (CNTs), we were able to detect and quantify MMP-14 using electrochemical impedance spectroscopy with a linear range of detection of 10 ng⋅mL⁻¹ to 100 ng⋅mL⁻¹, and LOD of 7.5 ng⋅mL⁻¹. The specificity of the inhibitory small molecule was validated against the PEX domain of MMP-1. The inhibitor loaded CNTs system showed as a desirable candidate to become an alternative to the conventional recognition bioelements for the detection of MMP-14. Full article

(This article belongs to the Special Issue Biosensing and Diagnosis of Cancer)

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(A) Schematic representation of NSC405020 molecule grafted onto CNTs surface followed by (B) SEM images for pristine, acylated, and inhibitor loaded CNTs (low and high magnification). Full article ">Figure 2
(A) FTIR spectrum (top) of pristine, acylated, and inhibitor loaded CNTs, respectively. The spectrum (down) of NSC 405020 molecule is also demonstrated. (B) CVs for GCE, pristine, acylated, and inhibitor loaded CNTs in PBS (pH 7.40) containing 10 mmol⋅mL−1 of K4[Fe (CN)6]−, 10 mmol mL−1 of K3[Fe (CN)6]− and 10 mmol.mL−1 of NaCl, scan rate 10 mV.s−1. Full article ">Figure 3
(A) Nyquist plots of inhibitor loaded CNTs before and after interaction with different concentrations of MPP-14 for 10 minutes in PBS (pH 7.40) containing 10 mmol.mL−1 of K3[Fe (CN)6]− and 10 mmol.mL−1 of NaCl. (B) Linear fit of EIS response for different concentrations of MMP-14, presenting LOD of 7.5 ng⋅mL−1. Significant difference between measurements was obtained at p-value < 0.05 (n = 2). Protein concentration varying from 10 ng.mL−1 to 100 ng.mL−1, applied potential of +0.20 V, from 50 kHz to 500 Hz, amplitude 50 mV. Full article ">Figure 4
(A) The inhibitor/protein interaction between small molecule NSC 405020 and the binding pocket of MMP-14 and (B) Schematic of the MMP-14 detection through the binding mechanism of protein and inhibitory small molecule as the recognition element. Full article ">Figure 5
EIS response for the inhibitor loaded CNT after individual interaction with 50 ng⋅mL−1 of MMP-1 and MMP-14 in PBS (pH 7.40) containing 10 mmol⋅mL−1 of K4[Fe (CN)6]− 10 mmol⋅mL−1 of K3[Fe (CN)6]− and 10 mmol⋅mL−1 of NaCl. The inhibitor loaded CNT showed specificity to MMP-14 (applied potential of +0.20 V, from 50 kHz to 500 Hz, amplitude 50 mV). Full article ">

11 pages, 1752 KiB

Open AccessArticle

Applications of Immunomagnetic Reduction Technology as a Biosensor in Therapeutic Evaluation of Chinese Herbal Medicine in Tauopathy Alleviation of an AD Drosophila Model

by Ming-Tsan Su, Chen-Wen Lu, Wen-Jhen Wu, Yong-Sin Jheng, Shieh-Yueh Yang, Wu-Chang Chuang, Ming-Chung Lee and Chung-Hsin Wu

Biosensors 2022, 12(10), 883; https://doi.org/10.3390/bios12100883 - 17 Oct 2022

Cited by 2 | Viewed by 2323

Abstract

Alzheimer’s disease (AD) is the most common form of dementia. The most convincing biomarkers in the blood for AD are currently β-amyloid (Aβ) and Tau protein because amyloid plaques and neurofibrillary tangles are pathological hallmarks in the brains of patients with AD. The [...] Read more.

Alzheimer’s disease (AD) is the most common form of dementia. The most convincing biomarkers in the blood for AD are currently β-amyloid (Aβ) and Tau protein because amyloid plaques and neurofibrillary tangles are pathological hallmarks in the brains of patients with AD. The development of assay technologies in diagnosing early-stage AD is very important. The study of human AD subjects is hindered by ethical and technical limitations. Thus, many studies have therefore turned to AD animal models, such as Drosophila melanogaster, to explore AD pathology. However, AD biomarkers such as Aβ and p-Tau protein in Drosophilamelanogaster occur at extremely low levels and are difficult to detect precisely. In this study, we applied the immunomagnetic reduction (IMR) technology of nanoparticles for the detection of p-Tau expressions in hTau^R406W flies, an AD Drosophila model. Furthermore, we used IMR technology as a biosensor in the therapeutic evaluation of Chinese herbal medicines in hTau^R406W flies with Tau-induced toxicity. To uncover the pathogenic pathway and identify therapeutic interventions of Chinese herbal medicines in Tau-induced toxicity, we modeled tauopathy in the notum of hTau^R406W flies. Our IMR data showed that the selected Chinese herbal medicines can significantly reduce p-Tau expressions in hTau^R406W flies. Using evidence of notal bristle quantification and Western blotting analysis, we confirmed the validity of the IMR data. Thus, we suggest that IMR can serve as a new tool for measuring tauopathy and therapeutic evaluation of Chinese herbal medicine in an AD Drosophila model. Full article

(This article belongs to the Special Issue Biosensors for Earlier Diagnosis of Alzheimer’s Disease)

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Schematic illustrating the more favorable therapeutic effects of Chinese herbal medicine treatment, which alleviates Tau-induced toxicity in hTauR406W Drosophila flies. Full article ">Figure 2
IMR detecting p-Tau 181 and standard curve: (A) A scheme of the physical mechanism of IMR assay. IMR is a method of assaying target molecules through measuring reductions in the mixed-frequency magnetic susceptibility of magnetic reagents resulting from the association between magnetic nanoparticles and target molecules. A magnetic nanoparticle coated with p-Tau 181 bioprobes is presented in the diagram. (B) Standard curve of p-Tau181 measured by IMR technique. The IMR value increased with the p-Tau 181 concentration. Full article ">Figure 3
IMR can be a biosensor in therapeutic evaluation of Chinese herbal medicine for tauopathy alleviation in AD hTauR406W flies: (A) Relationship between the p-Tau 181 concentrations and the number of hTauR406W flies (sampled number = 50, 100, 200) obtained through IMR assay. (B) The diagram Quantified comparison of p-Tau 181 concentrations and IMR values in hTauR406W flies (sampled number = 100) under sham and Chinese herbal medicine (CHM) treatment (three replicate experiments for each group). Values are mean ± SEM (** p < 0.01, Kruskal–Wallis non-parametric test for multiple comparisons and followed by the Mann–Whitney non-parametric test for comparisons of two independent samples). Full article ">Figure 4
Chinese herbal medicine treatment showed favorable therapeutic effects for tauopathy alleviation by notal bristle quantification: (A) Numbers of notal bristle (as indicated by arrows) within the red frames of the hTauR406W flies with sham and Chinese herbal medicine (CHM) treatments were notably lower than in their WT counterparts; hTauR406W flies under CHM treatments demonstrated higher notal bristle numbers than the hTauR406W flies under sham treatment. (B) Quantified comparison of the number of notal bristles among hTauR406W flies under sham and CHM treatments, and their WT counterparts (sampled number of flies = 30 for each group, three replicate experiments for each group). Values are mean ± SEM (** p < 0.01, two-way ANOVA followed by Mann–Whitney non-parametric test for comparisons). Full article ">Figure 5
Chinese herbal medicine treatment showed favorable therapeutic effects for tauopathy alleviation by Western blotting: (A) Example of Western blotting analysis of p-Tau 181 and total Tau expressions in hTauR406W flies and their WT counterparts under sham and Chinese herbal medicine (CHM) treatments. (B) Quantified comparison of the ratio of p-Tau 181 to total Tau expressions among hTauR406W flies under sham and CHM treatment (three replicate experiments for each group). Values are mean ± SEM (** p < 0.01, Kruskal–Wallis non-parametric test for multiple comparisons and followed by the Mann–Whitney non-parametric test for comparisons of two independent samples). kDa, kilodaltons. Full article ">

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Open AccessReview

Semiconductor Multimaterial Optical Fibers for Biomedical Applications

by Lingyu Shen, Chuanxin Teng, Zhuo Wang, Hongyi Bai, Santosh Kumar and Rui Min

Biosensors 2022, 12(10), 882; https://doi.org/10.3390/bios12100882 - 17 Oct 2022

Cited by 9 | Viewed by 5017

Abstract

Integrated sensors and transmitters of a wide variety of human physiological indicators have recently emerged in the form of multimaterial optical fibers. The methods utilized in the manufacture of optical fibers facilitate the use of a wide range of functional elements in microscale [...] Read more.

Integrated sensors and transmitters of a wide variety of human physiological indicators have recently emerged in the form of multimaterial optical fibers. The methods utilized in the manufacture of optical fibers facilitate the use of a wide range of functional elements in microscale optical fibers with an extensive variety of structures. This article presents an overview and review of semiconductor multimaterial optical fibers, their fabrication and postprocessing techniques, different geometries, and integration in devices that can be further utilized in biomedical applications. Semiconductor optical fiber sensors and fiber lasers for body temperature regulation, in vivo detection, volatile organic compound detection, and medical surgery will be discussed. Full article

(This article belongs to the Special Issue New Progress in Optical Fiber-Based Biosensors)

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