Nanomaterials

14 pages, 3783 KiB

Open AccessArticle

Synthesis of Highly Porous Lignin-Sulfonate Sulfur-Doped Carbon for Efficient Adsorption of Sodium Diclofenac and Synthetic Effluents

by Glaydson S. dos Reis, Sarah Conrad, Eder C. Lima, Mu. Naushad, Gopinathan Manavalan, Francesco G. Gentili, Guilherme Luiz Dotto and Alejandro Grimm

Nanomaterials 2024, 14(16), 1374; https://doi.org/10.3390/nano14161374 - 22 Aug 2024

Viewed by 590

Abstract

Herein, a novel sulfur-doped carbon material has been synthesized via a facile and sustainable single-step pyrolysis method using lignin-sulfonate (LS), a by-product of the sulfite pulping process, as a novel carbon precursor and zinc chloride as a chemical activator. The sulfur doping process [...] Read more.

Herein, a novel sulfur-doped carbon material has been synthesized via a facile and sustainable single-step pyrolysis method using lignin-sulfonate (LS), a by-product of the sulfite pulping process, as a novel carbon precursor and zinc chloride as a chemical activator. The sulfur doping process had a remarkable impact on the LS-sulfur carbon structure. Moreover, it was found that sulfur doping also had an important impact on sodium diclofenac removal from aqueous solutions due to the introduction of S-functionalities on the carbon material’s surface. The doping process effectively increased the carbon specific surface area (SSA), i.e., 1758 m² g⁻¹ for the sulfur-doped and 753 m² g⁻¹ for the non-doped carbon. The sulfur-doped carbon exhibited more sulfur states/functionalities than the non-doped, highlighting the successful chemical modification of the material. As a result, the adsorptive performance of the sulfur-doped carbon was remarkably improved. Diclofenac adsorption experiments indicated that the kinetics was better described by the Avrami fractional order model, while the equilibrium studies indicated that the Liu model gave the best fit. The kinetics was much faster for the sulfur-doped carbon, and the maximum adsorption capacity was 301.6 mg g⁻¹ for non-doped and 473.8 mg g⁻¹ for the sulfur-doped carbon. The overall adsorption seems to be a contribution of multiple mechanisms, such as pore filling and electrostatic interaction. When tested to treat lab-made effluents, the samples presented excellent performance. Full article

(This article belongs to the Special Issue Degradation of Pollutants by Nanostructured Photocatalysts)

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(a,c) XPS survey spectra for LS-carbon and LS-sulfur carbon samples and (b,d) deconvoluted S p2 peaks. Full article ">Figure 2
Proposed carbon network structures: (a) LS-carbon and (b) LS-sulfur carbon samples. Full article ">Figure 3
(a) N2 isotherm curves for LS-carbon and LS-sulfur carbon, (b) pore size distribution curves, (c) SEM image of LS-carbon, (d) SEM image of LS-sulfur carbon, (e) Raman spectrum of LS-carbon, and (f) Raman spectrum of LS-sulfur carbon. Full article ">Figure 4
(a) pHpzc of the LS-carbon and LS-sulfur carbon samples and (b) effect of the pH on DCF removal. Full article ">Figure 5
Kinetic measurements for the adsorption of DCF onto (a) LS-carbon and (b) LS-sulfur carbon samples. Initial pH of DCF solution was 6.0. Full article ">Figure 6
Isotherm curves for adsorption of DCF onto (a) LS-carbon and (b) LS-sulfur carbon samples. Initial pH of DCF solution was 6.0. Full article ">Figure 7
Adsorption of lab-made drug effluents. (a) Effluent A; (b) Effluent B. Full article ">

29 pages, 7083 KiB

Open AccessArticle

Mechanical and Shape Memory Properties of Additively Manufactured Polyurethane (PU)/Halloysite Nanotube (HNT) Nanocomposites

by Wendy Triadji Nugroho, Yu Dong and Alokesh Pramanik

Nanomaterials 2024, 14(16), 1373; https://doi.org/10.3390/nano14161373 - 22 Aug 2024

Viewed by 723

Abstract

This paper investigates the impact of halloysite nanotube (HNT) content on mechanical and shape memory properties of additively manufactured polyurethane (PU)/HNT nanocomposites. The inclusion of 8 wt% HNTs increases their tensile strength by 30.4% when compared with that of virgin PU at 44.75 [...] Read more.

This paper investigates the impact of halloysite nanotube (HNT) content on mechanical and shape memory properties of additively manufactured polyurethane (PU)/HNT nanocomposites. The inclusion of 8 wt% HNTs increases their tensile strength by 30.4% when compared with that of virgin PU at 44.75 MPa. Furthermore, consistently significant increases in tensile modulus, compressive strength and modulus, as well as specific energy absorption are also manifested by 47.2%, 34.0%, 125% and 72.7% relative to neat PU at 2.29 GPa, 3.88 MPa, 0.28 GPa and 0.44 kJ/kg respectively. However, increasing HNT content reduces lateral strain due to the restricted mobility of polymeric chains, leading to a decrease in negative Poisson’s ratio (NPR). As such, shape recovery ratio and time of PU/HNT nanocomposites are reduced by 9 and 45% with the inclusion of 10 wt% HNTs despite an increasing shape fixity ratio up to 12% relative to those of neat PU. Full article

(This article belongs to the Section Nanocomposite Materials)

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14 pages, 5368 KiB

Open AccessArticle

Functionalization of Polypropylene by TiO₂ Photocatalytic Nanoparticles: On the Importance of the Surface Oxygen Plasma Treatment

by Karolina Zajac, Joanna Macyk, Konrad Szajna, Franciszek Krok, Wojciech Macyk and Andrzej Kotarba

Nanomaterials 2024, 14(16), 1372; https://doi.org/10.3390/nano14161372 - 22 Aug 2024

Viewed by 609

Abstract

A new two-step method for developing a nanocomposite of polypropylene (PP) decorated with photocatalytically active TiO₂ nanoparticles (nTiO₂) is proposed. This method involves the low-temperature plasma functionalization of polypropylene followed by the ultrasound-assisted anchoring of nTiO₂. The nanoparticles, [...] Read more.

A new two-step method for developing a nanocomposite of polypropylene (PP) decorated with photocatalytically active TiO₂ nanoparticles (nTiO₂) is proposed. This method involves the low-temperature plasma functionalization of polypropylene followed by the ultrasound-assisted anchoring of nTiO₂. The nanoparticles, polymeric substrate, and resultant nanocomposite were thoroughly characterized using nanoparticle tracking analysis (NTA), microscopic observations (SEM, TEM, and EDX), spectroscopic investigations (XPS and FTIR), thermogravimetric analysis (TG/DTA), and water contact angle (WCA) measurements. The photocatalytic activity of the nanocomposites was evaluated through the degradation of methyl orange. The individual TiO₂ nanoparticles ranged from 2 to 6 nm in size. The oxygen plasma treatment of PP generated surface functional groups (mainly -OH and -C=O), transforming the surface from hydrophobic to hydrophilic, which facilitated the efficient deposition of nTiO₂. Optimized plasma treatment and sonochemical deposition parameters resulted in an active photocatalytic nTiO₂/PP system, degrading 80% of the methyl orange under UVA irradiation in 200 min. The proposed approach is considered versatile for the functionalization of polymeric materials with photoactive nanoparticles and, in a broader perspective, can be utilized for the fabrication of self-cleaning surfaces. Full article

(This article belongs to the Topic Preparation and Application of Polymer Nanocomposites)

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15 pages, 4359 KiB

Open AccessArticle

Enhancing Slurry Stability and Surface Flatness of Silicon Wafers through Organic Amine-Catalyzed Synthesis Silica Sol

by Yi Xing, Weilei Wang, Weili Liu and Zhitang Song

Nanomaterials 2024, 14(16), 1371; https://doi.org/10.3390/nano14161371 - 22 Aug 2024

Viewed by 735

Abstract

The stability of slurries used for chemical mechanical polishing (CMP) is a crucial concern in industrial chip production, influencing both the quality and cost-effectiveness of polishing fluids. In silicon wafer polishing, the conventional use of commercial neutral silica sol combined with organic bases [...] Read more.

The stability of slurries used for chemical mechanical polishing (CMP) is a crucial concern in industrial chip production, influencing both the quality and cost-effectiveness of polishing fluids. In silicon wafer polishing, the conventional use of commercial neutral silica sol combined with organic bases often leads to slurry instability. To address this issue, this study proposes organic amines—specifically ethanolamine (MEA), ethylenediamine (EDA), and tetramethylammonium hydroxide (TMAOH)—as catalysts for synthesizing alkaline silica sol tailored for silicon wafer polishing fluids. Sol–gel experiments and zeta potential measurements demonstrate the efficacy of this approach in enhancing the stability of silica sol. The quantitative analysis of surface hydroxyl groups reveals a direct correlation between enhanced stability and increased hydroxyl content. The application of the alkaline silica sol in silicon wafer polishing fluids improves polishing rates and enhances surface flatness according to atomic force microscopy (AFM). In addition, electrochemical experiments validate the capability of this polishing solution to mitigate corrosion on silicon wafer surfaces. These findings hold significant implications for the advancement of chemical mechanical polishing techniques in the field of integrated circuit fabrication. Full article

(This article belongs to the Special Issue Advanced Porous Nanomaterials: Synthesis, Properties, and Application)

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16 pages, 9972 KiB

Open AccessArticle

Influence of the Structure of Hydrothermal-Synthesized TiO₂ Nanowires Formed by Annealing on the Photocatalytic Reduction of CO₂ in H₂O Vapor

by Andrey M. Tarasov, Larisa I. Sorokina, Daria A. Dronova, Olga Volovlikova, Alexey Yu. Trifonov, Sergey S. Itskov, Aleksey V. Tregubov, Elena N. Shabaeva, Ekaterina S. Zhurina, Sergey V. Dubkov, Dmitry V. Kozlov and Dmitry Gromov

Nanomaterials 2024, 14(16), 1370; https://doi.org/10.3390/nano14161370 - 21 Aug 2024

Viewed by 611

Abstract

The present study investigates the photocatalytic properties of hydrothermally synthesized TiO₂ nanowires (NWs) for CO₂ reduction in H₂O vapor. It has been demonstrated that TiO₂ NWs, thermally treated at 500–700 °C, demonstrate an almost tenfold higher yield of [...] Read more.

The present study investigates the photocatalytic properties of hydrothermally synthesized TiO₂ nanowires (NWs) for CO₂ reduction in H₂O vapor. It has been demonstrated that TiO₂ NWs, thermally treated at 500–700 °C, demonstrate an almost tenfold higher yield of products compared to the known commercial powder TiO₂ P25. It has been found that the best material is a combination of anatase, TiO₂-B and rutile. The product yield increases with increasing heat treatment temperature of TiO₂ NWs. This is associated with an increase in the degree of crystallinity of the material. It is shown that the best product yield of the CO₂ reduction in H₂O vapor is achieved when the TiO₂ NW photocatalyst is heated to 100 °C. Full article

(This article belongs to the Section Energy and Catalysis)

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11 pages, 2975 KiB

Open AccessArticle

The Construction of Iodine-Doped Carbon Nitride as a Metal-Free Nanozyme for Antibacterial and Water Treatment

by Xinru Cai, Tongtong Xie, Linshan Luo and Xiting Li

Nanomaterials 2024, 14(16), 1369; https://doi.org/10.3390/nano14161369 - 21 Aug 2024

Viewed by 484

Abstract

Metal-free photocatalysis that produces reactive oxygen species (ROS) shows significant promising applications for environmental remediation. Herein, we constructed iodine-doped carbon nitride (I-CN) for applications in the photocatalytic inactivation of bacteria and the heterogeneous Fenton reaction. Our findings revealed that I-CN demonstrates superior photocatalytic [...] Read more.

Metal-free photocatalysis that produces reactive oxygen species (ROS) shows significant promising applications for environmental remediation. Herein, we constructed iodine-doped carbon nitride (I-CN) for applications in the photocatalytic inactivation of bacteria and the heterogeneous Fenton reaction. Our findings revealed that I-CN demonstrates superior photocatalytic activity compared to pure CN, due to enhanced light adsorption and a narrowed band gap. Antibacterial tests confirmed that I-CN exhibits exceptional antibacterial activity against both Escherichia coli and Staphylococcus aureus. The results showed that I-CN effectively generates superoxide radicals and hydroxyl radicals under light irradiation, resulting in enhanced antibacterial activity. In addition, I-CN can also be applied for a heterogeneous photo-Fenton-like reaction, achieving a high performance for the degradation of sulfamethoxazole (SMX), a typical antibiotic, via the photocatalytic activation of peroxymonosulfate (PMS). These results shed new light on the fabrication of metal-free nanozymes and their applications for disinfection and water decontamination. Full article

(This article belongs to the Special Issue Nanocatalysts for Environmental Remediation)

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(a) SEM image of I-CN; (b) TEM image of I-CN; (c) XRD patterns; (d) Raman spectra of I-CN and CN; (e) high-resolution N 1s XPS spectra; (f) high-resolution XPS I 3d spectra of I-CN. Full article ">Figure 2
(a) Photocurrent response; (b) Nyquist diagram of I-CN and CN; DMPO spin-trapping EPR spectra for (c) O2•− and (d) •OH under irradiation-simulated visible light (• represents DMPO–•OH and ◆ represents DMPO–O2•−). Full article ">Figure 3
(a) UV/Vis DRS spectra, (b) Tauc plots, (c) Mott–Schottky plots, and (d) band structure and photocatalytic mechanism of I-CN. Full article ">Figure 4
Bacterial colony growth in the presence of I-CN for (a) S. aureus and (b) E. coli under different irradiation times; (c,d) show the survival ratio. Full article ">Figure 5
(a) Absorption curves of TMB chromogenic reaction catalyzed by I-CN; (b) degradation of SMX in various systems; influence of (c) catalyst dose, (d) PMS dose, and (e) initial pH on SMX degradation in I-CN/PMS/Vis system; (f) recycling use of I-CN for degradation of SMX via PMS activation over five consecutive cycles. Reaction conditions: [SMX] = 10 mg/L; [catalyst] = 0.6 g/L; [PMS] = 0.3 g/L; initial pH = 5. Full article ">

16 pages, 4552 KiB

Open AccessArticle

In Situ, Nitrogen-Doped Porous Carbon Derived from Mixed Biomass as Ultra-High-Performance Supercapacitor

by Yuqiao Bai, Qizhao Wang, Jieni Wang, Shuqin Zhang, Chenlin Wei, Leichang Cao and Shicheng Zhang

Nanomaterials 2024, 14(16), 1368; https://doi.org/10.3390/nano14161368 - 21 Aug 2024

Viewed by 548

Abstract

How to address the destruction of the porous structure caused by elemental doping in biochar derived from biomass is still challenging. In this work, the in-situ nitrogen-doped porous carbons (ABPCs) were synthesized for supercapacitor electrode applications through pre-carbonization and activation processes using nitrogen-rich [...] Read more.

How to address the destruction of the porous structure caused by elemental doping in biochar derived from biomass is still challenging. In this work, the in-situ nitrogen-doped porous carbons (ABPCs) were synthesized for supercapacitor electrode applications through pre-carbonization and activation processes using nitrogen-rich pigskin and broccoli. Detailed characterization of ABPCs revealed that the best simple ABPC-4 exhibited a super high specific surface area (3030.2–3147.0 m² g⁻¹) and plentiful nitrogen (1.35–2.38 wt%) and oxygen content (10.08–15.35 wt%), which provided more active sites and improved the conductivity and electrochemical activity of the material. Remarkably, ABPC-4 showed an outstanding specific capacitance of 473.03 F g⁻¹ at 1 A g⁻¹. After 10,000 cycles, its capacitance retention decreased by only 4.92% at a current density of 10 A g⁻¹ in 6 M KOH. The assembled symmetric supercapacitor ABPC-4//ABPC-4 achieved a power density of 161.85 W kg⁻¹ at the maximum energy density of 17.51 Wh kg⁻¹ and maintained an energy density of 6.71 Wh kg⁻¹ when the power density increased to 3221.13 W kg⁻¹. This study provides a mixed doping approach to achieve multi-element doping, offering a promising way to apply supercapacitors using mixed biomass. Full article

(This article belongs to the Special Issue Nanomaterials for Energy Conversion and Storage (2nd Edition))

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14 pages, 4527 KiB

Open AccessArticle

ZIF-8-Based Nitrogen and Monoatomic Metal Co-Doped Pyrolytic Porous Carbon for High-Performance Supercapacitor Applications

by Xiaobo Han, Yihao Geng, Jieni Wang, Shuqin Zhang, Chenlin Wei, Leichang Cao and Shicheng Zhang

Nanomaterials 2024, 14(16), 1367; https://doi.org/10.3390/nano14161367 - 21 Aug 2024

Viewed by 584

Abstract

Metal–organic frameworks (MOFs) receive wide attention owing to their high specific surface area, porosity, and structural designability. In this paper, ZC-Ru and ZC-Cu electrodes loaded with monatomic Ru and Cu doped with nitrogen were prepared by pyrolysis, ion impregnation, and carbonization process using [...] Read more.

Metal–organic frameworks (MOFs) receive wide attention owing to their high specific surface area, porosity, and structural designability. In this paper, ZC-Ru and ZC-Cu electrodes loaded with monatomic Ru and Cu doped with nitrogen were prepared by pyrolysis, ion impregnation, and carbonization process using ZIF-8 synthesized by static precipitation as a precursor. ZC-Cu has a high specific surface area of 859.78 m² g⁻¹ and abundant heteroatoms O (10.04%) and N (13.9%), showing the specific capacitance of 222.21 F g⁻¹ at 0.1 A g⁻¹ in three-electrode system, and low equivalent series resistance (Rct: 0.13 Ω), indicating excellent energy storage capacity and electrical conductivity. After 10,000 cycles at 1 A g⁻¹ in 6 M KOH electrolyte, it still has an outstanding capacitance retention of 99.42%. Notably, symmetric supercapacitors ZC-Cu//ZC-Cu achieved the maximum power density and energy density of 485.12 W·kg⁻¹ and 1.61 Wh·kg⁻¹, respectively, positioning ZC-Cu among the forefront of previously known MOF-based electrode materials. This work demonstrates the enormous potential of ZC-Cu in the supercapacitor industry and provides a facile approach to the treatment of transition metal. Full article

(This article belongs to the Special Issue Nanomaterials for Energy Conversion and Storage (2nd Edition))

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13 pages, 25965 KiB

Open AccessArticle

MIL-Derived Hollow Tubulous-Shaped In₂O₃/ZnIn₂S₄ Z-Scheme Heterojunction for Efficient Antibacterial Performance via In Situ Composite

by Jiao Duan, Hui Zhang, Jie Zhang, Mengmeng Sun and Jizhou Duan

Nanomaterials 2024, 14(16), 1366; https://doi.org/10.3390/nano14161366 - 21 Aug 2024

Viewed by 477

Abstract

In this study, a hollow tubulous-shaped In₂O₃ derived from MIL (MIL-68 (In)) exhibited an enhanced specific surface area compared to MIL. To further sensitize In₂O₃, ZnIn₂S₄ was grown in situ on the derived [...] Read more.

In this study, a hollow tubulous-shaped In₂O₃ derived from MIL (MIL-68 (In)) exhibited an enhanced specific surface area compared to MIL. To further sensitize In₂O₃, ZnIn₂S₄ was grown in situ on the derived In₂O₃. The 40In₂O₃/ZnIn₂S₄ composite (1 mmol ZnIn₂S₄ loaded on 40 mg In₂O₃) exhibited degradation rates of methyl orange (MO) under visible light (80 mW·cm⁻², 150 min) that were 17.9 and 1.4 times higher than those of the pure In₂O₃ and ZnIn₂S₄, respectively. Moreover, the 40In₂O₃/ZnIn₂S₄ exhibited an obviously improved antibacterial performance against Pseudomonas aeruginosa, with an antibacterial rate of 99.8% after visible light irradiation of 80 mW cm⁻² for 420 min. The 40In₂O₃/ZnIn₂S₄ composite showed the highest photocurrent density, indicating an enhanced separation of photogenerated charge carriers. Electron spin resonance results indicated that the 40In₂O₃/ZnIn₂S₄ composite generated both ·O₂⁻ and ·OH radicals under visible light, whereas ·OH radicals were almost not detected in ZnIn₂S₄ alone, suggesting the presence of a Z-scheme heterojunction between In₂O₃ and ZnIn₂S₄, thereby enhancing the degradation and antibacterial capabilities of the composite. This offers fresh perspectives on designing effective photocatalytic materials for use in antibacterial and antifouling applications. Full article

(This article belongs to the Special Issue Heterogeneous Photocatalysts Based on Nanocomposites)

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14 pages, 5143 KiB

Open AccessArticle

A Self-Powered, Skin Adhesive, and Flexible Human–Machine Interface Based on Triboelectric Nanogenerator

by Xujie Wu, Ziyi Yang, Yu Dong, Lijing Teng, Dan Li, Hang Han, Simian Zhu, Xiaomin Sun, Zhu Zeng, Xiangyu Zeng and Qiang Zheng

Nanomaterials 2024, 14(16), 1365; https://doi.org/10.3390/nano14161365 - 20 Aug 2024

Viewed by 691

Abstract

Human–machine interactions (HMIs) have penetrated into various academic and industrial fields, such as robotics, virtual reality, and wearable electronics. However, the practical application of most human–machine interfaces faces notable obstacles due to their complex structure and materials, high power consumption, limited effective skin [...] Read more.

Human–machine interactions (HMIs) have penetrated into various academic and industrial fields, such as robotics, virtual reality, and wearable electronics. However, the practical application of most human–machine interfaces faces notable obstacles due to their complex structure and materials, high power consumption, limited effective skin adhesion, and high cost. Herein, we report a self-powered, skin adhesive, and flexible human–machine interface based on a triboelectric nanogenerator (SSFHMI). Characterized by its simple structure and low cost, the SSFHMI can easily convert touch stimuli into a stable electrical signal at the trigger pressure from a finger touch, without requiring an external power supply. A skeleton spacer has been specially designed in order to increase the stability and homogeneity of the output signals of each TENG unit and prevent crosstalk between them. Moreover, we constructed a hydrogel adhesive interface with skin-adhesive properties to adapt to easy wear on complex human body surfaces. By integrating the SSFHMI with a microcontroller, a programmable touch operation platform has been constructed that is capable of multiple interactions. These include medical calling, music media playback, security unlocking, and electronic piano playing. This self-powered, cost-effective SSFHMI holds potential relevance for the next generation of highly integrated and sustainable portable smart electronic products and applications. Full article

(This article belongs to the Special Issue Self-Powered Flexible Sensors Based on Triboelectric Nanogenerators)

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Overview diagram of the proposed SSFHMI. (a) The proposed SSFHMI and its application in intelligence interaction, medical calls, media player control, password unlocking, and electronic keyboard playing. (b) Construction of the SSFHMI. (c) Atomic-scale and macroscopic charge transfer mechanisms during friction between PDMS and PTFE. (i) PDMS and PTFE are in Separated stage. (ii) Compressing stage. (iii) Compressed stage. (iv) Separating stage. (d) The diagram of the mechanism of adhesion effect after contact between the adhesive layer and the human tissue. (e) Photograph of the proposed SSFHMI. (i) MCU connected with SSFHMI. (ii) SSFHMI attached to the back of the hand. Full article ">Figure 2
Preparation, properties of the hydrogel-based adhesive layer. (a) Schematic illustration of the material used to prepare the adhesive layer. (b) Steps and methods for preparing the adhesive layer. (c) The tensile stress-strain curves and dynamic strain amplitude curves of the nanocomposite hydrogel adhesives. (i) Tensile stress-strain curves of LAP nanosheets at different concentrations. (ii) Self-healing characteristic curve. (d) Photograph of the adhesive layer for bonding SSFHMI to biological tissues, and the viscosity curve of the adhesive layer. Full article ">Figure 3
Electrical characterization of the TENG. (a) Illustration of the macro-level working mechanism of a single-electrode TENG. (i) Compressing. (ii) Compressed. (iii) Separating. (iv) Separated. (b–d) Open-circuit voltage, short-circuit current, and short-circuit charge at the working frequency of 3 Hz, respectively. (e) Output voltage, current, and power density under the different external load resistances. (f) Output voltage of the TENG during 18,000 working cycles. Full article ">Figure 4
The output characterization of the TENG array on the proposed SSFHMI. (a) The output waveform of nine TENGs. (b) The output voltage of nine TENGs. (c) Results of the two-sample T-test performed between TENGs. (d) 3D heat map corresponding to the different pressing positions on the TENG array. Full article ">Figure 5
The signal coding of the proposed SSFHMI for intelligent control. (a) Schematic diagram of the human–computer interaction using SSFHMI. (b) Password lock function of the T9 keyboard and its 3D heat map of corresponding operations. (c) Application of the medical call. (i) Practical application demonstration. (ii) Comparison with similar work in Structure Complexity and Anti-interference [<a href="#B45-nanomaterials-14-01365" class="html-bibr">45</a>,<a href="#B46-nanomaterials-14-01365" class="html-bibr">46</a>,<a href="#B47-nanomaterials-14-01365" class="html-bibr">47</a>,<a href="#B48-nanomaterials-14-01365" class="html-bibr">48</a>,<a href="#B49-nanomaterials-14-01365" class="html-bibr">49</a>,<a href="#B50-nanomaterials-14-01365" class="html-bibr">50</a>,<a href="#B51-nanomaterials-14-01365" class="html-bibr">51</a>,<a href="#B52-nanomaterials-14-01365" class="html-bibr">52</a>]. Full article ">

14 pages, 2462 KiB

Open AccessArticle

Development of a Gold Nanoparticle-Based Sensor for Authentication of Organic Milk Based on Differential Levels of miRNA

by Karelmar Lopez-Benitez, Patricia Alcazar-Gonzalez, Loubna Abou el qassim, Mª Teresa Fernandez-Argüelles, Fernando Vicente, Luis J. Royo and Mario Menendez-Miranda

Nanomaterials 2024, 14(16), 1364; https://doi.org/10.3390/nano14161364 - 19 Aug 2024

Viewed by 614

Abstract

Dairy production systems significantly impact environmental sustainability, animal welfare, and human health. Intensive farming maximizes output through high-input practices, raising concerns about environmental degradation, animal welfare, and health risks from antibiotic residues. Conversely, organic farming emphasizes sustainable practices, animal welfare, and minimal synthetic [...] Read more.

Dairy production systems significantly impact environmental sustainability, animal welfare, and human health. Intensive farming maximizes output through high-input practices, raising concerns about environmental degradation, animal welfare, and health risks from antibiotic residues. Conversely, organic farming emphasizes sustainable practices, animal welfare, and minimal synthetic inputs, potentially enhancing biodiversity, soil health, and milk quality. MicroRNAs (miRNAs), non-coding RNAs regulating gene expression, are promising biomarkers due to their response to various conditions. In this study, miRNAs bta-miR-103 and bta-miR-155, which are abundant in milk from pasture-fed cows, were selected. Additionally, bta-miR-215, which is abundant in milk fat from intensive systems, was also studied, in order to differentiate dairy production systems. A novel, cost-effective gold nanoparticle (AuNP)-based sensor was developed for miRNA detection, leveraging the unique plasmonic properties of AuNPs for visual detection. The method involves functionalizing AuNPs with complementary RNA probes and detecting miRNA-induced aggregation through colorimetric changes. This rapid, results in 30 min, and sensitive, visual limit of detection of 200 nM, assay requires minimal instrumentation and can be easily interpreted, offering significant advantages for field implementation in characterizing dairy production systems. This study demonstrates the successful application of this sensor in detecting miRNAs in 350 nM miRNA spiked raw milk, highlighting its potential for in situ dairy industry applications. Full article

(This article belongs to the Special Issue Synthesis and Applications of Gold Nanoparticles: 2nd Edition)

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Full article ">Figure 1
(a) Absorbance spectrum of the synthesized AuNPs; (b) TEM image of AuNPs. Full article ">Figure 2
(a) Scheme of the Head-to-Head (H-H) conformation for the hybridization process. (b) Scheme representation of the Tail-to-Tail (T-T) conformation for the hybridization process. Full article ">Figure 3
Scheme of the detection assay. Full article ">Figure 4
Agarose gel electrophoresis was carried out to optimize the concentration of AggA, AggB, AggC, and AggD for the detection of bta-miR-103. Bioconjugation with different molar ratios of each DNA probe per functionalized AuNP is shown. Full article ">Figure 5
(a) Magnesium chloride optimization for the T-T assay format detection of bta-miR-103; (b) hybridization time optimization for the T-T assay format detection of bta-miR-155; (c) hybridization temperature optimization for the T-T assay format detection of bta-miR-215; − no presence of the analyte; + in presence of the analyte. TLC spots were carried out in triplicate (n = 3). Full article ">Figure 6
Visual limit of detection determination. (a) Visual LOD for bta-miR-103 using H-H (upper row) and T-T (lower row) assay formats. (b) Visual LOD for bta-miR-155 using H-H (upper row) and T-T (lower row) assay formats. (c) Visual LOD for bta-miR-215 using H-H (upper row) and T-T (lower row) assay formats. TLC spots were carried out in triplicate (n = 3). Full article ">Figure 7
(a) Sample analysis using T-T conformations for raw milk (upper row) and spiked sample with 350 nM miR103, miR155, and miR215 (lower row). (b) Sample analysis using H-H conformations for raw milk (upper row) and spiked sample with 350 nM miR103, miR155, and miR215 (lower row). (c) Spiked sample 2 with 350 nM miR103 (upper row); spiked sample 3 with 350 nM miR155 (middle row); and spiked sample 4 with 350 nM miR215 (lower row). TLC spots were carried out in triplicate (n = 3). Full article ">

26 pages, 8300 KiB

Open AccessArticle

Adipocyte-Targeted Nanocomplex with Synergistic Photothermal and Pharmacological Effects for Combating Obesity and Related Metabolic Syndromes

by Yuanyuan Zhang, Xiaojiao Zeng, Fan Wu, Xiaopeng Yang, Tingting Che, Yin Zheng, Jie Li, Yufei Zhang, Xinge Zhang and Zhongming Wu

Nanomaterials 2024, 14(16), 1363; https://doi.org/10.3390/nano14161363 - 19 Aug 2024

Viewed by 924

Abstract

Obesity is a global epidemic which induces a multitude of metabolic disorders. Browning of white adipose tissue (WAT) has emerged as a promising therapeutic strategy for promoting weight loss and improving associated metabolic syndromes in people with obesity. However, current methods of inducing [...] Read more.

Obesity is a global epidemic which induces a multitude of metabolic disorders. Browning of white adipose tissue (WAT) has emerged as a promising therapeutic strategy for promoting weight loss and improving associated metabolic syndromes in people with obesity. However, current methods of inducing white adipose tissue browning have limited applicability. We developed a nanocomplex pTSL@(P+I), which is a temperature-sensitive liposome (TSL) surface-conjugated with an adipocyte-targeting peptide (p) and loaded with both browning-promoting agents (P) and photosensitizing agents (I). This nanocomplex exhibits adipocyte targeting, as well as synergistic pharmacological and photothermal properties to promote browning. pTSL@(P+I) effectively upregulates UCP1 and COX5B expression by activating the transcription axis of PPARγ/PGC1α and HSF1/PGC1α, thereby promoting white adipose tissue browning and reducing obesity. This novel nanocomplex exhibited a uniform spherical shape, with an average diameter of approximately 200 nm. Additionally, the nanocomplexes exhibited remarkable photothermal properties and biocompatibility. Further, when adipocytes were treated with pTSL@(P+I), their triglyceride content decreased remarkably and intracellular mitochondrial activity increased significantly. When applied to diet-induced obesity (DIO) mice, the nanocomplex exhibited significant efficacy, demonstrating a notable 14.4% reduction in body weight from the initial measurement, a decreased fat/lean mass ratio of 20.8%, and no statistically significant disparities (p > 0.05) in associated side effects when compared to the control group. In summary, implementation of the targeted nanocomplex pTSL@(P+I) to enhance energy expenditure by stimulating white adipose tissue browning offers a promising therapeutic approach for the treatment of obesity and related metabolic syndromes. Full article

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(A) 1H NMR spectra of DSPE-PEG2000-Mal in CDCl3 and DSPE-PEG2000-Pep in CD4O. (B) TEM images of targeted nanocomplex pTSL@(P+I). (C) Histogram of the particle size distribution of pTSL@(P+I) measured by DLS. (D) Potential distribution of the targeted nanocomplex measured by DLS. (E) UV–visible-near infrared (UV–VIS-NIR) spectrum of pTSL@(P+I). (F) Particle size stability of pTSL@(P+I) at 25 °C and 37 °C measured by DLS. Photothermal conversion curves (G) and photothermal images (H) of different concentrations of pTSL@(P+I) after irradiation with 808-nm NIR light (1.0 W/cm2) for various durations. (I) Photothermal conversion curves of pTSL@(P+I) at a concentration of 500 μg/mL under varying powers and durations when exposed to 808-nm NIR light. (J) Cumulative release curves of Piog from pTSL@(P+I) at 37 °C and 45 °C, respectively. (K) Hemolysis of different concentrations of pTSL@(P+I). (L) 3T3-L1 cell and differentiated 3T3-L1 cell survival rates measured by CCK-8 method after treatment with different concentrations of pTSL@(P+I) for 48 h. Full article ">Figure 2
(A) After labeling TSL@(P+I) and pTSL@(P+I) with FITC fluorescent probes, CLSM images of differentiated 3T3-L1 cells following co-incubation with TSL@(P+I), pTSL@(P+I), and anti-prohibitin + pTSL@(P+I) for 1 h (left) or 3 h (right), respectively. (the DAPI-stained nucleus as blue fluorescence, the FITC-labeled nanocomplex as green fluorescence) (B) Quantification of the average fluorescence intensity (FI) of FITC in 3T3-L1 cells from each experimental group in (A) using Image J 1.8.0 software. (C) Schematic diagram of cell culture and intervention process. Oil Red O-stained images of 3T3-L1 cells induced differentiation and intervened in each group (D,E) and quantification of lipid droplets after extraction with isopropanol (F). (G) Quantification of the number of lipid droplets per cell following various interventions (n = 5). Concentrations of lipid triglyceride (TAG) (H) and free fatty acid (FFA) (I) in differentiated 3T3-L1 cells subjected to various interventions. Visualization of mitochondrial fluorescence (J) in differentiated 3T3-L1 cells following various interventions and quantification of the average fluorescence intensity (FI) (K) in cells from each experimental group in (J) using Image J 1.8.0 software. (the DAPI-stained nucleus as blue fluorescence, the Mito-Tracker as red fluorescence) * p < 0.05, ** p < 0.01, *** p < 0.001, **** p < 0.0001; ns = not significant. Statistical significance was assessed via two-way ANOVA (B) and one-way ANOVA (F–K). Full article ">Figure 3
(A) Protein expression levels of PGC1α, HSF1, PPARγ, UCP1, and COX5B were assessed via Western blot analysis in each group of 3T3-L1 cells following induction of differentiation and intervention. (B–F) Quantitative analysis of the corresponding protein levels in (A) was conducted using Image J 1.8.0 software. The levels of inflammatory factors IL-1β (G) and TNF-α (H) were measured by ELISA in each group of 3T3-L1 cells following induction of differentiation and intervention. * p < 0.05, ** p < 0.01, *** p < 0.001, **** p < 0.0001; ns = not significant. Statistical significance was assessed via one-way ANOVA. Full article ">Figure 4
(A) A schematic diagram illustrating the in vivo experiments conducted on mice (HI: Latin for hypodermic injection). (B) Representative effect plots depicting the outcomes observed in each group of diet-induced obesity mice following a 4-week treatment. Assessment of daily changes in body weight (C) and dietary food intake (D) of mice (n = 5) in each intervention group. (E) Analysis of the weight ratio of fat/lean at the experiment’s endpoint using a small animal body fat analyzer (n = 5). Typical anatomical drawings (F) and corresponding weights (G) of eWAT, iWAT and BAT of mice (n = 5) in each experimental group at the endpoint. (H) After subcutaneous injection of nanocomplexes into both sides of the iWAT of mice in each group, infrared thermal imaging images of the left inguinal region of mice were irradiated by 808 nm NIR light (0.5 W/cm2) at different times. (I) Quantitative analysis of photothermal conversion in the left inguinal area of mice in the PBS, pTSL@I, and pTSL@(P+I) groups at different times with irradiation of 808 nm NIR light (0.5 W/cm2) in (H) (n = 3). (J) Quantitative analysis of left and right groin temperature before and after laser irradiation of left groin in pTSL@I and pTSL@(P+I) groups in (H) (n = 3). * p < 0.05, ** p < 0.01, *** p < 0.001, **** p < 0.0001; ns = not significant. Statistical significance was assessed via one-way ANOVA. Full article ">Figure 5
Glucose measurements and area under the curve of glucose tolerance test (GTT) (A,B) and insulin tolerance test (ITT) (C,D) in each group of diet-induced obesity mice after treatment (n = 5). The 24 h mean activity counts (E), mean and time-point O2 consumption (F,G), mean and time-point CO2 production (H,I), and mean respiratory quotient (RQ) (J) in mice analyzed by physiological metabolic cages (n = 3). Body temperatures of diet-induced obesity mice (K) and area under the curve (L) in each group during a 4 h cold tolerance test before the end of the experiment (n = 3). * p < 0.05, ** p < 0.01, *** p < 0.001, **** p < 0.0001; ns = not significant. Statistical significance was assessed via one-way ANOVA. Full article ">Figure 6
(A–C) Levels of lipid triglyceride (TAG), TC, and LDL-C in each group of mice (n = 5) at the endpoint of the experiment. Protein expression levels of PGC1α, HSF1, PPARγ, UCP1, and COX5B in iWAT after intervention were detected using Western blotting in each group of mice (D) and quantitative analysis of corresponding protein levels by Image J 1.8.0 software (E–I). * p < 0.05, ** p < 0.01, *** p < 0.001, **** p < 0.0001; ns = not significant. Statistical significance was assessed via one-way ANOVA. Full article ">Figure 7
Levels of iWAT inflammatory cytokines IL-1β (A) and TNF-α (B) in mice measured by ELISA. (C) H&E staining of typical iWAT and eWAT of mice in each group after treatment. (D) Morphometric analysis of adipocyte cell sizes (n = 100 data points) in (C). Uncoupling protein 1 (UCP-1) labeled immunohistochemical staining (E) and quantification of UCP-1 expression (F) in (E) using Image J 1.8.0 software and UCP-1 labeled immunofluorescence images (G) and quantification of UCP-1 expression (H) in (G) using Image J 1.8.0 software of typical iWAT and eWAT of mice in each group after treatment. * p < 0.05, ** p < 0.01, **** p < 0.0001; ns = not significant. Statistical significance was assessed via one-way ANOVA. Full article ">Scheme 1
(A) Composition and structure of targeted nanocomplex pTSL@(P+I). (B) NIR light-activated targeted nanocomplex for white adipose tissue browning to enhance anti-obesity effects in mice. Full article ">Scheme 2
Anti-obesity mechanisms of pTSL@(P+I)-mediated photothermal and pharmacological synergistic therapy. Full article ">

23 pages, 31708 KiB

Open AccessArticle

Development of In Situ Methods for Preparing La-Mn-Co-Based Compounds over Carbon Xerogel for Oxygen Reduction Reaction in an Alkaline Medium

by Jhony Xavier Flores-Lasluisa, Bryan Carré, Joachim Caucheteux, Philippe Compère, Alexandre F. Léonard and Nathalie Job

Nanomaterials 2024, 14(16), 1362; https://doi.org/10.3390/nano14161362 - 19 Aug 2024

Viewed by 579

Abstract

Metal oxides containing La, Mn, and Co cations can catalyze oxygen reduction reactions (ORRs) in electrochemical processes. However, these materials require carbon support and optimal interactions between both compounds to be active. In this work, two approaches to prepare composites of La-Mn-Co-based compounds [...] Read more.

Metal oxides containing La, Mn, and Co cations can catalyze oxygen reduction reactions (ORRs) in electrochemical processes. However, these materials require carbon support and optimal interactions between both compounds to be active. In this work, two approaches to prepare composites of La-Mn-Co-based compounds over carbon xerogel were developed. Using sol-gel methods, either the metal-based material was deposited on the existing carbon xerogel or vice versa. The metal oxide selected was the LaMn_0.7Co_0.3O₃ perovskite, which has good catalytic behavior and selectivity towards direct ORRs. All the as-prepared composites were tested for ORRs in alkaline liquid electrolytes and characterized by diverse physicochemical techniques such as XRD, XPS, SEM, or N₂ adsorption. Although the perovskite structure either decomposed or failed to form using those in situ methods, the materials exhibited great catalytic activity, which can be ascribed to the strengthening of the interactions between oxides and the carbon support via C-O-M covalent bonds and to the formation of new active sites such as the MnO/Co heterointerfaces. Moreover, Co-N_x-C species are formed during the synthesis of the metal compounds over the carbon xerogel. These species possess a strong catalytic activity towards ORR. Therefore, the composites formed by synthesizing metal compounds over the carbon xerogel exhibit the best performance in the ORR, which can be ascribed to the presence of the MnO/Co heterointerfaces and Co-N_x-C species and the strong interactions between both compounds. Moreover, the small nanoparticle size leads to a higher number of active sites available for the reaction. Full article

(This article belongs to the Special Issue Carbon Nanomaterials for Electrocatalytic Application)

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X-ray diffraction patterns for the pristine perovskite (P), carbon xerogel (CX), and composite materials. (▬) P; (▬) P + CX; (▬) CX; (▬) CX_P_N2; (▬) CX_P_O2; (▬) P_CX_5.6; (▬) P_CX_5.3. Full article ">Figure 2
TEM images for the different samples: (a,d) P + CX; (b,e) CX_P_N2; and (c,f) P_CX_5.3. Inset (b): magnification of the region indicated by the arrow. Full article ">Figure 3
SEM images for the different samples: (a) pristine perovskite (P); (b) CX; (c) P + CX; (d) CX_P_N2; and (e) P_CX_5.3. Full article ">Figure 4
N2 adsorption isotherms at −196 °C for the pristine CX and P samples and the composites containing both compounds. (▬) P; (▬) CX; (▬) P + CX; (▬) CX_P_N2; (▬) CX_P_O2; (▬) P_CX_5.6; (▬) P_CX_5.3. Full article ">Figure 5
Deconvolution of the Mn 2p (a) and O 1s (b) of the composites. Full article ">Figure 6
Cyclic voltammetry of the composites in 0.1 M KOH medium saturated with either N2 (a) or O2 (b). Scan rate: 10 mV s−1. (▬) CX; (▬) CX_P_N2; (▬) CX_P_O2; (▬) P_CX_5.6; (▬) P_CX_5.3. All current densities are reported by the geometric area of the electrode. Full article ">Figure 7
(a) RDE linear sweep voltammograms for composites in 0.1 M KOH saturated with O2 at 1600 rpm; (b) number of electrons involved in ORR at increasing potential. (▬) P; (▬) CX; (▬) P + CX; (▬) CX_P_N2; (▬) CX_P_O2; (▬) P_CX_5.6; (▬) P_CX_5.3; (▬) 20 wt.% Pt/C. All current densities are reported by the geometric area of the electrode. Full article ">

22 pages, 4474 KiB

Open AccessReview

Sensors Based on Molecularly Imprinted Polymers in the Field of Cancer Biomarker Detection: A Review

by Camila Quezada, S. Shiva Samhitha, Alexis Salas, Adrián Ges, Luis F. Barraza, María Carmen Blanco-López, Francisco Solís-Pomar, Eduardo Pérez-Tijerina, Carlos Medina and Manuel Meléndrez

Nanomaterials 2024, 14(16), 1361; https://doi.org/10.3390/nano14161361 - 19 Aug 2024

Viewed by 665

Abstract

Biomarkers play a pivotal role in the screening, diagnosis, prevention, and post-treatment follow-up of various malignant tumors. In certain instances, identifying these markers necessitates prior treatment due to the complex nature of the tumor microenvironment. Consequently, advancing techniques that exhibit selectivity, specificity, and [...] Read more.

Biomarkers play a pivotal role in the screening, diagnosis, prevention, and post-treatment follow-up of various malignant tumors. In certain instances, identifying these markers necessitates prior treatment due to the complex nature of the tumor microenvironment. Consequently, advancing techniques that exhibit selectivity, specificity, and enable streamlined analysis hold significant importance. Molecularly imprinted polymers (MIPs) are considered synthetic antibodies because they possess the property of molecular recognition with high selectivity and sensitivity. In recent years, there has been a notable surge in the investigation of these materials, primarily driven by their remarkable adaptability in terms of tailoring them for specific target molecules and integrating them into diverse analytical technologies. This review presents a comprehensive analysis of molecular imprinting techniques, highlighting their application in developing sensors and analytical methods for cancer detection, diagnosis, and monitoring. Therefore, MIPs offer great potential in oncology and show promise for improving the accuracy of cancer screening and diagnosis procedures. Full article

(This article belongs to the Section Biology and Medicines)

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9 pages, 1811 KiB

Open AccessArticle

Green Phytic Acid-Assisted Synthesis of LiMn_1-xFe_xPO₄/C Cathodes for High-Performance Lithium-Ion Batteries

by Yueying Li, Chenlu Hu, Zhidong Hou, Chunguang Wei and Jian-Gan Wang

Nanomaterials 2024, 14(16), 1360; https://doi.org/10.3390/nano14161360 - 19 Aug 2024

Viewed by 707

Abstract

As a promising cathode material, olivine-structured LiMnPO₄ holds enormous potential for lithium-ion batteries. Herein, we demonstrate a green biomass-derived phytic-acid-assisted method to synthesize a series of LiMn_1−xFe_xPO₄/C composites. The effect of Fe doping on the crystal [...] Read more.

As a promising cathode material, olivine-structured LiMnPO₄ holds enormous potential for lithium-ion batteries. Herein, we demonstrate a green biomass-derived phytic-acid-assisted method to synthesize a series of LiMn_1−xFe_xPO₄/C composites. The effect of Fe doping on the crystal structure and morphology of LiMnPO₄ particles is investigated. It is revealed that the optimal Fe doping amount of x = 0.2 enables a substantial enhancement of interfacial charge transfer ability and Li⁺ ion diffusion kinetics. Consequently, a large reversible capacity output of 146 mAh g⁻¹ at 0.05 C and a high rate capacity of 77 mAh g⁻¹ at 2 C were acquired by the as-optimized LiMn_0.8Fe_0.2PO₄/C cathode. Moreover, the LiMn_0.8Fe_0.2PO₄/C delivered a specific capacity of 68 mAh g⁻¹ at 2 C after 500 cycles, with a capacity retention of 88.4%. This work will unveil a green synthesis route for advancing phosphate cathode materials toward practical implementation. Full article

(This article belongs to the Topic Advanced Nanomaterials for Lithium-Ion Batteries)

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Full article ">Figure 1
(a) Schematic illustration for the fabrication of LMFP/C-x. SEM images of (b) LMP/C, (c) LMFP/C-0.1, (d) LMFP/C-0.2, and (e) LMFP/C-0.4. (f) TEM and (g) HRTEM images of LMFP/C-0.2. Full article ">Figure 2
(a) XRD patterns and (b) Raman spectra of LMP/C, LMFP/C-0.1, LMFP/C-0.2, and LMFP/C-0.4 with an enlarged XRD profile of (020) plane (right part). (c) TGA curve of LMFP/C-0.2. (d) N2 adsorption–desorption isotherms of various samples. Full article ">Figure 3
(a) XPS survey spectrum of LMFP/C-0.2. High-resolution XPS spectra of (b) Mn 2p, (c) Fe 2p, and (d) P 2p of LMFP/C-0.2. Full article ">Figure 4
(a) CV curves at a scan rate of 0.05 mV s−1, (b) charge/discharge curves, (c) cycling stabilities at 0.05 C, and (d) rate performances of LMFP/C, LMFP/C-0.1, LMFP/C-0.2, and LMFP/C-0.4. (e) Long-term stability of LMFP/C-0.2 at 2 C (inset: SEM images of the electrode before (left) and after (right) cycling test). Full article ">Figure 5
(a) Nyquist plots and (b) corresponding relationship between Z′ and ω−1/2 of the electrodes in the low-frequency region. Full article ">

12 pages, 3437 KiB

Open AccessArticle

Analysis of 3D Channel Current Noise in Small Nanoscale MOSFETs Using Monte Carlo Simulation

by Wenpeng Zhang, Qun Wei, Xiaofei Jia and Liang He

Nanomaterials 2024, 14(16), 1359; https://doi.org/10.3390/nano14161359 - 18 Aug 2024

Viewed by 594

Abstract

As field effect transistors are reduced to nanometer dimensions, experimental and theoretical research has shown a gradual change in noise generation mechanisms. There are few studies on noise theory for small nanoscale transistors, and Monte Carlo (MC) simulations mainly focus on 2D devices [...] Read more.

As field effect transistors are reduced to nanometer dimensions, experimental and theoretical research has shown a gradual change in noise generation mechanisms. There are few studies on noise theory for small nanoscale transistors, and Monte Carlo (MC) simulations mainly focus on 2D devices with larger nanoscale dimensions. In this study, we employed MC simulation techniques to establish a 3D device simulation process. By setting device parameters and writing simulation programs, we simulated the raw data of channel current noise for a silicon-based metal–oxide–semiconductor field-effect transistor (MOSFET) with a 10 nm channel length and calculated the drain output current based on these data, thereby achieving static testing of the simulated device. Additionally, this study obtained a 3D potential distribution map of the device channel surface area. Based on the original data from the simulation analysis, this study further calculated the power spectral density of the channel current noise and analyzed how the channel current noise varies with gate voltage, source–drain voltage, temperature, and substrate doping density. The results indicate that under low-temperature conditions, the channel current noise of the 10 nm MOSFET is primarily composed of suppressed shot noise, with the proportion of thermal noise in the total noise slightly increasing as temperature rises. Under normal operating conditions, the channel current noise characteristics of the 10 nm MOSFET device are jointly characterized by suppressed shot noise, thermal noise, and cross-correlated noise. Among these noise components, shot noise is the main source of noise, and its suppression degree decreases as the bias voltage is reduced. These findings are consistent with experimental observations and theoretical analyses found in the existing literature. Full article

(This article belongs to the Special Issue Integrated Circuit Research for Nanoscale Field-Effect Transistors)

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12 pages, 5082 KiB

Open AccessArticle

Excellent Hole Mobility and Out–of–Plane Piezoelectricity in X–Penta–Graphene (X = Si or Ge) with Poisson’s Ratio Inversion

by Sitong Liu, Xiao Shang, Xizhe Liu, Xiaochun Wang, Fuchun Liu and Jun Zhang

Nanomaterials 2024, 14(16), 1358; https://doi.org/10.3390/nano14161358 - 17 Aug 2024

Viewed by 405

Abstract

Recently, the application of two–dimensional (2D) piezoelectric materials has been seriously hindered because most of them possess only in–plane piezoelectricity but lack out–of–plane piezoelectricity. In this work, using first–principles calculation, by atomic substitution of penta–graphene (PG) with tiny out–of–plane piezoelectricity, we design and [...] Read more.

Recently, the application of two–dimensional (2D) piezoelectric materials has been seriously hindered because most of them possess only in–plane piezoelectricity but lack out–of–plane piezoelectricity. In this work, using first–principles calculation, by atomic substitution of penta–graphene (PG) with tiny out–of–plane piezoelectricity, we design and predict stable 2D X–PG (X = Si or Ge) semiconductors with excellent in–plane and out–of–plane piezoelectricity and extremely high in–plane hole mobility. Among them, Ge–PG exhibits better performance in all aspects with an in–plane strain piezoelectric coefficient d₁₁ = 8.43 pm/V, an out–of–plane strain piezoelectric coefficient d₃₃ = −3.63 pm/V, and in–plane hole mobility μ_h = 57.33 × 10³ cm² V⁻¹ s⁻¹. By doping Si and Ge atoms, the negative Poisson’s ratio of PG approaches zero and reaches a positive value, which is due to the gradual weakening of the structure’s mechanical strength. The bandgaps of Si–PG (0.78 eV) and Ge–PG (0.89 eV) are much smaller than that of PG (2.20 eV), by 2.82 and 2.47 times, respectively. This indicates that the substitution of X atoms can regulate the bandgap of PG. Importantly, the physical mechanism of the out–of–plane piezoelectricity of these monolayers is revealed. The super–dipole–moment effect proposed in the previous work is proved to exist in PG and X–PG, i.e., it is proved that their out–of–plane piezoelectric stress coefficient e₃₃ increases with the super–dipole–moment. The e₃₃–induced polarization direction is also consistent with the super–dipole–moment direction. X–PG is predicted to have prominent potential for nanodevices applied as electromechanical coupling systems: wearable, ultra–thin devices; high–speed electronic transmission devices; and so on. Full article

(This article belongs to the Special Issue Structural Modeling and Theoretical Study of Low-Dimensional Materials)

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Top and side views of 2 × 2 supercells of (a) PG, (b) Si–PG, and (c) Ge–PG. Full article ">Figure 2
The phonon spectra with corresponding phonon density of states (PHDOS) of (a) Si–PG and (b) Ge–PG monolayers. (c) Formation energy; (d) Young’s modulus (in units of N/m); (e) Poisson’s ratio of PG and X–PG; (f,g) AIMD simulations of ground states of X–PG. Full article ">Figure 3
Planer–average charge density difference with Bader charge analysis (in red numbers) and electrostatic potentials of (a) PG, (b) Si–PG, and (c) Ge–PG monolayers. Band structures with the corresponding projected density of states (PDOS) of (d) Si–PG and (e) Ge–PG. The unit of PDOS is states/(eV • unit cell). The Fermi level is set to zero. Full article ">Figure 4
(a) The energy shifting and (b) band–edge positions as a function of the uniaxial strain in the x or y transport direction in PG and X–PG monolayers. Full article ">Figure 5
(a) Electron–contributed, ion–contributed, and total values of the out–of–plane piezoelectric stress coefficient e33 of X–PG monolayers. (b) The e33 value of PG and X–PG as a function of the super–dipole–moment inside them. (c) Schematic diagram of the out–of–plane piezoelectric strain coefficient d33 of Ge–PG. Full article ">

20 pages, 4735 KiB

Open AccessArticle

Behavior of Polymer Electrode PEDOT:PSS/Graphene on Flexible Substrate for Wearable Biosensor at Different Loading Modes

by Mariya Aleksandrova, Valentin Mateev and Ivo Iliev

Nanomaterials 2024, 14(16), 1357; https://doi.org/10.3390/nano14161357 - 17 Aug 2024

Viewed by 603

Abstract

In recent years, flexible and wearable biosensor technologies have gained significant attention due to their potential to revolutionize healthcare monitoring. Among the various components involved in these biosensors, the electrode material plays a crucial role in ensuring accurate and reliable detection. In this [...] Read more.

In recent years, flexible and wearable biosensor technologies have gained significant attention due to their potential to revolutionize healthcare monitoring. Among the various components involved in these biosensors, the electrode material plays a crucial role in ensuring accurate and reliable detection. In this regard, polymer electrodes, such as Poly(3,4 ethylenedioxythiophene): poly(styrenesulfonate), combined with graphene (PEDOT:PSS/graphene), have emerged as promising candidates due to their unique mechanical properties and excellent electrical conductivity. Understanding the mechanical behavior of these polymer electrodes on flexible substrates is essential to ensure the stability and durability of wearable biosensors. In this paper, PEDOT:PSS/graphene composite was spray-coated on flexible substrates at different growth conditions to explore the effect of the deposition parameters and mode of mechanical loading (longitudinal or transversal) on the electrical and mechanical behavior of the fabricated samples. It was found that the coating grown at lower temperatures and higher spraying pressure exhibited stable behavior no matter the applied stress type. Full article

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10 pages, 3795 KiB

Open AccessArticle

WS₂ with Controllable Layer Number Grown Directly on W Film

by Yuxin Zhang, Shiyi Feng, Jin Guo, Rong Tao, Zhixuan Liu, Xiangyi He, Guoxia Wang and Yue Wang

Nanomaterials 2024, 14(16), 1356; https://doi.org/10.3390/nano14161356 - 16 Aug 2024

Viewed by 465

Abstract

As a layered material with single/multi-atom thickness, two-dimensional transition metal sulfide WS₂ has attracted extensive attention in the field of science for its excellent physical, chemical, optical, and electrical properties. The photoelectric properties of WS₂ are even more promising than graphene. [...] Read more.

As a layered material with single/multi-atom thickness, two-dimensional transition metal sulfide WS₂ has attracted extensive attention in the field of science for its excellent physical, chemical, optical, and electrical properties. The photoelectric properties of WS₂ are even more promising than graphene. However, there are many existing preparation methods for WS₂, but few reports on its direct growth on tungsten films. Therefore, this paper studies its preparation method and proposes an innovative two-dimensional material preparation method to grow large-sized WS₂ with higher quality on metal film. In this experiment, it was found that the reaction temperature could regulate the growth direction of WS₂. When the temperature was below 950 °C, the film showed horizontal growth, while when the temperature was above 1000 °C, the film showed vertical growth. At the same time, through Raman and band gap measurements, it is found that the different thicknesses of precursor film will lead to a difference in the number of layers of WS₂. The number of layers of WS₂ can be controlled by adjusting the thickness of the precursor. Full article

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11 pages, 3201 KiB

Open AccessArticle

Substrate Charge Transfer Induced Ferromagnetism in MnSe/SrTiO₃ Ultrathin Films

by Chun-Hao Huang, Chandra Shekar Gantepogu, Peng-Jen Chen, Ting-Hsuan Wu, Wei-Rein Liu, Kung-Hsuan Lin, Chi-Liang Chen, Ting-Kuo Lee, Ming-Jye Wang and Maw-Kuen Wu

Nanomaterials 2024, 14(16), 1355; https://doi.org/10.3390/nano14161355 - 16 Aug 2024

Viewed by 559

Abstract

The observation of superconductivity in MnSe at 12 GPa motivated us to investigate whether superconductivity could be induced in MnSe at ambient conditions. A strain-induced structural change in the ultrathin film could be one route to the emergence of superconductivity. In this report, [...] Read more.

The observation of superconductivity in MnSe at 12 GPa motivated us to investigate whether superconductivity could be induced in MnSe at ambient conditions. A strain-induced structural change in the ultrathin film could be one route to the emergence of superconductivity. In this report, we present the physical property of MnSe ultrathin films, which become tetragonal (stretched ab-plane and shortened c-axis) on a (001) SrTiO₃ (STO) substrate, prepared by the pulsed laser deposition (PLD) method. The physical properties of the tetragonal MnSe ultrathin films exhibit very different characteristics from those of the thick films and polycrystalline samples. The tetragonal MnSe films show substantial conductivity enhancement, which could be associated with the presence of superparamagnetism. The optical absorption data indicate that the electron transition through the indirect bandgap to the conduction band is significantly enhanced in tetragonal MnSe. Furthermore, the X-ray Mn L-edge absorption results also reveal an increase in unoccupied state valance bands. This theoretical study suggests that charge transfer from the substrate plays an important role in conductivity enhancement and the emergence of a ferromagnetic order that leads to superparamagnetism. Full article

(This article belongs to the Special Issue Synthesis and Ferroelectric, Photoelectric, Magnetic Properties of Thin Films)

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Cross-sectional TEM image of the three studied MnSe films. The measured thicknesses are (a) 30 nm, (b) 140 nm, and (c) 740 nm. The ink (white layer in each image) is a carbon paste used as a layer on the top of the films to protect from damage during the TEM sample preparation process. The regions (i), (ii), (iii), and (iv) marked in the images are Pt (conduction layer for FIB process), ink (organic protection layer), MnSe film, and STO substrate. Full article ">Figure 2
The temperature dependence of the resistivity of MnSe films. The resistivity decreases dramatically as the thickness of the film becomes thinner, more than one order of magnitude smaller in the 30 nm film than that of the 740 nm film. Full article ">Figure 3
The magnetic susceptibility of (a) polycrystalline MnSe powder and the (b) 740 nm, (c) 140 nm, and (d) 30 nm MnSe films. The polycrystalline MnSe sample was prepared via the solid-state reaction method. Its magnetic characteristics exhibit anomalies at 180 K and 270 K, respectively. The magnetic anomaly at 270 K arises from the antiferromagnetic order of the solitary hexagonal phase, with a partial transformation into the cubic phase [<a href="#B14-nanomaterials-14-01355" class="html-bibr">14</a>]. The magnetic anomaly observed at 180 K is attributed to the antiferromagnetic order of both the collective hexagonal and cubic phases [<a href="#B14-nanomaterials-14-01355" class="html-bibr">14</a>]. The 180 K magnetic anomaly in the polycrystalline sample is only observed in thick (740 nm) films. It is noted that the magnetic susceptibility of the film increases substantially as film thickness decreases. Full article ">Figure 4
An M-H curve of the MnSe films. (a) The M-H curve of films reveals the signatures of superparamagnetism, rapid increase at the low magnetic field region, saturation at the high magnetic region, and no hysteresis (zero coercive field). There is a small hysteresis loop in the low field region, as shown in <a href="#app1-nanomaterials-14-01355" class="html-app">Figure S2</a>. The moment is in the order of 10−4 emu and higher, which is well beyond the sensitivity of SQUID, ~10−6 emu. (b) The fitting of the M-H curve of the 20 nm film. The fitting curve (red line) agrees excellently with the experimental data (open circles). The extracted density of the magnetic domain is about 5.74 × 1018 cm−3, and the effective magnetic moment of Mn is about 3.21. Full article ">Figure 5
X-ray diffractions of the MnSe thin films. (a) A radial scan of the MnSe films with thicknesses of 30 nm, 140 nm, and 740 nm on the (001) STO substrate. The films were grown with the c-axis preferred orientation. The * mark (>3 orders of magnitude smaller than the (001) peak) at q near 2.8 Å−1 and 4.0 Å−1 are indexed as (112) and (222) peaks of MnSe. (b) A radical scan near the MnSe (002) peak. The peak of the 30 nm film shifts to a higher angle, implying a shorter c-axis lattice constant. (c) ψ-scan profiles with respect to the (022)STO and (101)MnSe diffraction peaks of the 30 nm film. A 4-fold symmetry in the ab-plane at 45° with respect to the STO a- (b-) axis demonstrates the epitaxial growth of the MnSe film. (d) The (200), (020), and (002) diffraction peaks of the 140 nm film. Their positions have no significant difference. (e) The (200), (020), and (002) diffraction peaks of the 30 nm film. The in-plane diffraction peak is located at a lower angle compared with the (002) peak. Full article ">Figure 6
Mn L-edge X-ray absorption spectra of the studied MnSe films. The XANES (X-ray absorption near edge spectroscopy) spectra of the Mn 2p3/2 to 3d (L3) transition. Four peaks are identified, (marked as A, B, C, and D) which originated from different Mn 3d-related final states. The inset shows the full spectrum of L-edge absorption. Full article ">Figure 7
The band structure of tetragonal MnSe. (a) The A-AFM phase. (b) The FM phase. For comparison, an identical unit cell is used for both phases. A rigid shift of 0.7 eV is applied to the conduction bands, as mentioned in the text. Full article ">

10 pages, 1994 KiB

Open AccessArticle

Enhanced Thermal Stability of Conductive Mercury Telluride Colloidal Quantum Dot Thin Films Using Atomic Layer Deposition

by Edward W. Malachosky, Matthew M. Ackerman and Liliana Stan

Nanomaterials 2024, 14(16), 1354; https://doi.org/10.3390/nano14161354 - 16 Aug 2024

Viewed by 572

Abstract

Colloidal quantum dots (CQDs) are valuable for their potential applications in optoelectronic devices. However, they are susceptible to thermal degradation during processing and while in use. Mitigating thermally induced sintering, which leads to absorption spectrum broadening and undesirable changes to thin film electrical [...] Read more.

Colloidal quantum dots (CQDs) are valuable for their potential applications in optoelectronic devices. However, they are susceptible to thermal degradation during processing and while in use. Mitigating thermally induced sintering, which leads to absorption spectrum broadening and undesirable changes to thin film electrical properties, is necessary for the reliable design and manufacture of CQD-based optoelectronics. Here, low-temperature metal–oxide atomic layer deposition (ALD) was investigated as a method for mitigating sintering while preserving the optoelectronic properties of mercury telluride (HgTe) CQD films. ALD-coated films are subjected to temperatures up to 160 °C for up to 5 h and alumina (Al₂O₃) is found to be most effective at preserving the optical properties, demonstrating the feasibility of metal–oxide in-filling to protect against sintering. HgTe CQD film electrical properties were investigated before and after alumina ALD in-filling, which was found to increase the p-type doping and hole mobility of the films. The magnitude of these effects depended on the conditions used to prepare the HgTe CQDs. With further investigation into the interaction effects of CQD and ALD process factors, these results may be used to guide the design of CQD–ALD materials for their practical integration into useful optoelectronic devices. Full article

(This article belongs to the Section Synthesis, Interfaces and Nanostructures)

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Infrared absorption spectra plotted against the wavelength (nm) of HgTe CQD thin films on sapphire substrates measured as a function of atomic layer deposition cycles and bake conditions. Evolution of the infrared absorption spectrum for HgTe CQD after (a) ZnO, (b) TiO2, (c) 4 cycles of alumina, (d) 8 cycles of alumina, and (e) 20 cycles of alumina and being subjected to baking up to 165 °C for up to 5 h. Full article ">Figure 2
Log plots of the current versus voltage for HgTe CQD thin film Au-Au photoconductor devices with a 5-microns electrode gap. The conductance for a control device (black) that was not subjected to atomic layer deposition, a film subjected to 8 cycles of alumina ALD (red), and a film subjected to 20 cycles alumina ALD (green) are plotted for comparison. Conductance of HgTe CQD films measured (a) before and (b) after baking at 130 °C for 2 h under a nitrogen environment are shown. Full article ">Figure 3
Transfer curves for HgTe colloidal quantum dot thin films measured at a 1 V source–drain bias (a) before alumina ALD and (b) after alumina ALD. Black dashed lines indicate the maximum and minimum slopes taken to calculate the carrier mobilities. Full article ">Figure 4
Transfer curves for n-type doped HgTe colloidal quantum dot thin films measured at a 1 V source–drain bias (a) before alumina ALD and (b) after alumina ALD. Black dashed lines indicate the maximum and minimum slopes taken to calculate the carrier mobilities. Full article ">

12 pages, 3269 KiB

Open AccessArticle

The Adsorption Behavior of Gas Molecules on Mn/N- and Mn-Doped Graphene

by Tingyue Xie, Cuifeng Tian, Ping Wang and Guozheng Zhao

Nanomaterials 2024, 14(16), 1353; https://doi.org/10.3390/nano14161353 - 15 Aug 2024

Viewed by 566

Abstract

By using density functional theory (DFT), the adsorption behavior of gas molecules on defective graphene doped with manganese and nitrogen were investigated. The geometric structure, electronic structure, and magnetic properties of two substrates were calculated and the sensing mechanism was also analyzed. The [...] Read more.

By using density functional theory (DFT), the adsorption behavior of gas molecules on defective graphene doped with manganese and nitrogen were investigated. The geometric structure, electronic structure, and magnetic properties of two substrates were calculated and the sensing mechanism was also analyzed. The results indicate that the MnSV-GP and MnN₃-GP have stronger structural stability, in which Mn atoms and their coordination atoms will become the adsorption point for five gas molecules (CH₂O, CO, N₂O, SO₂, and NH₃), respectively. Moreover, at room temperature (298 K), the recovery time of the MnSV-GP sensor for N₂O gas molecules is approximately 1.1 s. Therefore, it can be concluded that the MnSV-GP matrix as a magnetic gas sensor has a promising potential for detecting N₂O. These results also provide a new pathway for the potential application of Mn-doped graphene in the field of gas sensors. Full article

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(a,b) The geometric structure, top and side view, obtained from geometry optimization. (c,d) Charge density difference in MnSV-GP and MnN3-GP, respectively. Yellow contours indicate electron accumulation, and cyan contours indicate electron depletion. And other colors represent the chemical elements. Full article ">Figure 2
The adsorption energies of five gas molecules adsorbed on two Mn/GN catalysts. Each calculated binding energy is denoted as its absolute value. Full article ">Figure 3
DOS and PDOS distribution: before and after gas molecule adsorption on MnSV-GP (a) CH2O, (b) CO, (c) N2O, (d) SO2, and (e) NH3. Fermi energy is set to zero. Full article ">Figure 4
DOS and PDOS distribution: before and after gas molecule adsorption on MnN3-GP (a) CH2O, (b) CO, (c) N2O, (d) SO2, and (e) NH3. Full article ">Figure 5
The charge density differences in (a–e) CH2O, CO, N2O, SO2, and NH3 adsorbed on the MnSV-GP and (f–j) CH2O, CO, N2O, SO2, and NH3 adsorbed on the MnN3-GP configuration. Yellow contours indicate electron accumulation, and cyan contours indicate electron depletion. And other colors present chemical elements, such as purple color denotes Mn atom. Isosurface value: 0.002 e/Bohr3. Full article ">Figure 6
The spin density for two supports and gas-support chemisorption systems. (a) The spin density of the MnSV-GP before adsorption; (b–f) The spin density of the MnSV-GP after adsorption of CH2O, CO, N2O, SO2, and NH3, respectively; (g) The spin density of the MnN3-GP before adstorption; (h–l) The spin density of the MnN3-GP after adsorption of CH2O, CO, N2O, SO2, and NH3, respectively. The yellow and cyan areas indicate the positive and negative spin densities respectively; isosurface value: 0.005 e/Bohr3. And other colors present chemical elements, such as red and green color represent oxygen and sulfur atom, respectively. Full article ">

13 pages, 8468 KiB

Open AccessArticle

Construction of Ternary Ce Metal–Organic Framework/Bi/BiOCl Heterojunction towards Optimized Photocatalytic Performance

by Teng Gao, Hongqi Chu, Shijie Wang, Zhenzi Li and Wei Zhou

Nanomaterials 2024, 14(16), 1352; https://doi.org/10.3390/nano14161352 - 15 Aug 2024

Viewed by 617

Abstract

Photocatalysis is the most promising green approach to solve antibiotic pollution in water, but the actual treatment effect is limited by photocatalytic activity. Herein, Bi and BiOCl were loaded onto the surface of Ce-MOF (metal–organic framework) using an electrostatic adsorption method, and a [...] Read more.

Photocatalysis is the most promising green approach to solve antibiotic pollution in water, but the actual treatment effect is limited by photocatalytic activity. Herein, Bi and BiOCl were loaded onto the surface of Ce-MOF (metal–organic framework) using an electrostatic adsorption method, and a special ternary heterojunction of Ce/Bi/BiOCl was successfully prepared as a photocatalyst for the degradation of tetracycline (TC). FTIR demonstrated that the obtained photocatalyst contains functional groups such as -COOH belonging to Ce-MOF and characteristic crystal planes of Bi and BiOCl, indicating the successful construction of a ternary photocatalyst. The results of UV–vis absorption spectra confirm that the band gap of Ce/Bi/BiOCl heterojunction is reduced from 3.35 eV to 2.7 eV, resulting in an enhanced light absorption capability in the visible light region. The special ternary heterojunction constructed by Ce-MOF, Bi, and BiOCl could achieve a narrow band gap and reasonable band structure, thereby enhancing the separation of photogenerated charges. Consequently, the photocatalytic performance of the Ce/Bi/BiOCl ternary heterojunction was significantly enhanced compared to Ce-MOF, Bi, and BiOCl. Therefore, Ce/Bi/BiOCl can achieve a photocatalytic degradation rate of 97.7% within 20 min, which is much better than Bi (14.8%) and BiOCl (67.9%). This work successfully constructed MOF-based ternary photocatalysts and revealed the relationship between ternary heterojunctions and photocatalytic activity. This provides inspiration for constructing other heterogeneous catalysts for use in the field of photocatalysis. Full article

(This article belongs to the Special Issue Controlled Synthesis and Catalytic Applications of Oxide-Based Nanoparticles)

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XRD patterns of Ce-MOF, Bi/BiOCl, BiOCl, and Ce/Bi/BiOCl, respectively. Full article ">Figure 2
TEM images (a,b) and high-resolution TEM images (c,d) of Ce/Bi/BiOCl. Full article ">Figure 3
(a) N2 adsorption/desorption isotherms of Ce-MOF, Bi/BiOCl, BiOCl, and Ce/Bi/BiOCl. (b) Pore size distribution curves of Ce-MOF, Bi/BiOCl, and Ce/Bi/BiOCl. Full article ">Figure 4
XPS spectra of Ce/Bi/BiOCl: (a) Bi 4f, (b) Cl 2p, (c) Ce 3d, and (d) O 1 s. The XPS characterization was performed on Ce/Bi/BiOCl to probe the chemical states. (e) FTIR spectra of Ce-MOF, Bi/BiOCl, BiOCl, and Ce/Bi/BiOCl, respectively. Full article ">Figure 5
(a) Ultraviolet–visible absorption spectra of Ce-MOF, Bi/BiOCl, BiOCl, and Ce/Bi/BiOCl and (b) the corresponding Kubelka–Munk conversion reflection spectra. (c) Mott–Schottky test. (d) Energy diagram. (e) Transient photocurrent responses. (f) EIS Nyquist plots. Full article ">Figure 6
(a) Photocatalytic activities, (b) kinetic analysis, and (c) pseudo-first-order kinetic constants of Bi/BiOCl, BiOCl, and Ce/Bi/BiOCl, respectively. (d) Mineralization of TC over Bi/BiOCl, BiOCl, and Ce/Bi/BiOCl. Full article ">Figure 7
(a) Trapping experiments of active species for Ce/Bi/BiOCl; (b) EPR signals for ·O2− and (c) ·OH. Full article ">Figure 8
(a) Repeatability experiment of Ce/Bi/BiOCl photocatalytic degradation of TC. XRD (b) and FTIR (c) of Ce/Bi/BiOCl after reusability test. Full article ">

31 pages, 4738 KiB

Open AccessArticle

Synthesized Bis-Triphenyl Phosphonium-Based Nano Vesicles Have Potent and Selective Antibacterial Effects on Several Clinically Relevant Superbugs

by Silvana Alfei, Guendalina Zuccari, Francesca Bacchetti, Carola Torazza, Marco Milanese, Carlo Siciliano, Constantinos M. Athanassopoulos, Gabriella Piatti and Anna Maria Schito

Nanomaterials 2024, 14(16), 1351; https://doi.org/10.3390/nano14161351 - 15 Aug 2024

Viewed by 669

Abstract

The increasing emergence of multidrug-resistant (MDR) pathogens due to antibiotic misuse translates into obstinate infections with high morbidity and high-cost hospitalizations. To oppose these MDR superbugs, new antimicrobial options are necessary. Although both quaternary ammonium salts (QASs) and phosphonium salts (QPSs) possess antimicrobial [...] Read more.

The increasing emergence of multidrug-resistant (MDR) pathogens due to antibiotic misuse translates into obstinate infections with high morbidity and high-cost hospitalizations. To oppose these MDR superbugs, new antimicrobial options are necessary. Although both quaternary ammonium salts (QASs) and phosphonium salts (QPSs) possess antimicrobial effects, QPSs have been studied to a lesser extent. Recently, we successfully reported the bacteriostatic and cytotoxic effects of a triphenyl phosphonium salt against MDR isolates of the Enterococcus and Staphylococcus genera. Here, aiming at finding new antibacterial devices possibly active toward a broader spectrum of clinically relevant bacteria responsible for severe human infections, we synthesized a water-soluble, sterically hindered quaternary phosphonium salt (BPPB). It encompasses two triphenyl phosphonium groups linked by a C12 alkyl chain, thus embodying the characteristics of molecules known as bola-amphiphiles. BPPB was characterized by ATR-FTIR, NMR, and UV spectroscopy, FIA-MS (ESI), elemental analysis, and potentiometric titrations. Optical and DLS analyses evidenced BPPB tendency to self-forming spherical vesicles of 45 nm (DLS) in dilute solution, tending to form larger aggregates in concentrate solution (DLS and optical microscope), having a positive zeta potential (+18 mV). The antibacterial effects of BPPB were, for the first time, assessed against fifty clinical isolates of both Gram-positive and Gram-negative species. Excellent antibacterial effects were observed for all strains tested, involving all the most concerning species included in ESKAPE bacteria. The lowest MICs were 0.250 µg/mL, while the highest ones (32 µg/mL) were observed for MDR Gram-negative metallo-β-lactamase-producing bacteria and/or species resistant also to colistin, carbapenems, cefiderocol, and therefore intractable with currently available antibiotics. Moreover, when administered to HepG2 human hepatic and Cos-7 monkey kidney cell lines, BPPB showed selectivity indices > 10 for all Gram-positive isolates and for clinically relevant Gram-negative superbugs such as those of E. coli species, thus being very promising for clinical development. Full article

(This article belongs to the Section Biology and Medicines)

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15 pages, 4190 KiB

Open AccessArticle

Impact of Nanoplastic Particles on Macrophage Inflammation and Intestinal Health in a Mouse Model of Inflammatory Bowel Disease

by Marlene Schwarzfischer, Tano S. Ruoss, Anna Niechcial, Sung Sik Lee, Marcin Wawrzyniak, Andrea Laimbacher, Kirstin Atrott, Roberto Manzini, Marijn Wilmink, Luise Linzmeier, Yasser Morsy, Silvia Lang, Gerhard Rogler, Ralf Kaegi, Michael Scharl and Marianne R. Spalinger

Nanomaterials 2024, 14(16), 1350; https://doi.org/10.3390/nano14161350 - 15 Aug 2024

Viewed by 764

Abstract

Background: The increasing presence of plastics in the human diet is raising public concern about the potential risks posed by nanoplastic (NP) particles, which can emerge from the degradation of plastic debris. NP ingestion poses particular risks to individuals with inflammatory bowel disease [...] Read more.

Background: The increasing presence of plastics in the human diet is raising public concern about the potential risks posed by nanoplastic (NP) particles, which can emerge from the degradation of plastic debris. NP ingestion poses particular risks to individuals with inflammatory bowel disease (IBD), as compromised epithelial barriers may facilitate NP translocation. Methods: In vitro, bone-marrow-derived macrophages (BMDMs) were exposed to 25 nm polymethacrylate (PMMA) or 50 nm polystyrene (PS) particles to assess morphological changes and alterations in pro- and anti-inflammatory gene expression. In vivo, mice received PMMA NP particles for 6 months before acute dextran sodium sulfate (DSS) colitis was induced to investigate NP impacts on intestinal health and inflammation. Results: PMMA and PS NP exposure in BMDMs induced morphological changes indicative of a proinflammatory phenotype characterized by enlarged amoeboid cell shapes. It also triggered an inflammatory response, indicated by increased expression of proinflammatory cytokines such as Tnfa and Il6. Unexpectedly, long-term PMMA NP administration did not affect the intestinal epithelial barrier or exacerbate acute DSS-induced colitis in mice. Colonoscopy and histological analysis revealed no NP-related changes, suggesting adverse effects on intestinal health or inflammation. Conclusion: Our findings from animal models offer some reassurance to IBD patients regarding the effects of NP ingestion. However, variations in lifestyle and dietary habits may lead to significantly higher plastic intake in certain individuals, raising concerns about potential long-term gastrointestinal effects of lifelong plastic consumption. Full article

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NP particles caused phenotypic changes in BMDMs. Bone marrow was isolated from 10-week-old WT mice and cells were differentiated into BMDMs before treatment with 25 nm PMMA or 50 nm PS particles at a concentration of 100, 200, or 400 µg/mL for 2, 4, 8, or 24 h. (A) Schematic overview of experimental procedure. (B) Bright-field images of BMDMs after NP exposure. Original magnification (BF) 40×. Full article ">Figure 2
NP particles were engulfed by BMDMs and resulted in rearrangement of the cytoskeleton and phenotypical changes. Bone marrow was isolated from 10-week-old WT mice and cells were differentiated into BMDMs before treatment with green-fluorescent 25 nm PMMA or 50 nm PS particles at a concentration of 100 µg/mL for 24 h. Confocal microscopy of NP (green)-treated cells stained with DAPI (blue) and Phalloidin (red). White arrows indicate enlarged vacuoles. Full article ">Figure 3
NP administration activated BMDMs and induced proinflammatory cytokine expression. Bone marrow from 10-week-old WT mice was differentiated into BMDMs, then treated with 25 nm PMMA or 50 nm PS particles (100, 200, or 400 µg/mL) for 2, 4, 8, or 24 h. Relative mRNA levels of cytokines (A) Tnfα (B) Il6, (C) Il12b) and costimulatory molecules (D) Cd80, (E) Cd86) following exposure to 25 nm (left) and 50 nm (right) particles are shown. Red asterisks indicate significant differences compared to controls. ∆∆CT method and one-way ANOVA (* = p ≤ 0.05, ** = p ≤ 0.01, *** = p ≤ 0.001, **** = p ≤ 0.0001). Full article ">Figure 4
NPs did not affect intestinal homeostasis. Directly after weaning, female WT mice were supplemented with 25 nm PMMA particles in the drinking water (0.05 mg/mL) for 172 days (6 months). (A) Weight development during pretreatment. (B) Representative colonoscopy images and MEICS scores. (C) H&E staining of distal colon sections with analysis of epithelial damage and infiltration. (D) Colon length and (E) spleen weight. (F) Epithelial barrier integrity assessed by quantifying FITC-dextran levels in serum 5 h after oral administration of 4 kDa FITC-dextran. (A,B) Two-way ANOVA with Tukey’s multiple comparisons. (B,C) Kruskal–Wallis test. (D–F) One-way ANOVA. Original magnification (H&E) ×10. Full article ">Figure 5
Administration of NP particles did not exacerbate acute DSS colitis. Directly after weaning, female WT mice were supplemented with 25 nm PMMA particles in the drinking water (0.05 mg/mL) for 172 days (6 months). Acute colitis was induced by administration of 1.5% DSS in the drinking water for 7 days. (A) Weight development during NP pretreatment and (B) colitis induction. (C) Representative images from colonoscopy and MEICS score. (D) H&E staining of distal colon sections and analysis of epithelial damage and infiltration. (E) Colon length and (F) spleen weight. (A,B) Two-way ANOVA Tukey’s multiple comparison (C,D) Kruskal–Wallis Test. (E,F) One-way ANOVA. Original magnification (H&E) ×10. Full article ">

18 pages, 20009 KiB

Open AccessArticle

Optimization of Cyanide-Free Composite Electrodeposition Based on π-π Interactions Preparation of Silver-Graphene Composite Coatings for Electrical Contact Materials

by Luyi Sun, Xin Chen, Ming Zhou, Jingwei Gao, Chaogui Luo, Xiao Li, Shengli You, Mingyue Wang and Gangqiang Cheng

Nanomaterials 2024, 14(16), 1349; https://doi.org/10.3390/nano14161349 - 15 Aug 2024

Viewed by 571

Abstract

With the rapid development of industrial automation and power electronics, the requirements for electrical contact materials are increasing. However, traditional electrical contact materials encountered significant bottlenecks in terms of performance enhancement and production environmental friendliness. Therefore, this paper proposes a new material design [...] Read more.

With the rapid development of industrial automation and power electronics, the requirements for electrical contact materials are increasing. However, traditional electrical contact materials encountered significant bottlenecks in terms of performance enhancement and production environmental friendliness. Therefore, this paper proposes a new material design idea that utilizes π-π interactions between graphene and compounds with conjugated structures in order to achieve uniform dispersion of graphene in the metal matrix and thus enhance the performance of composites. Based on this design idea, we used nicotinic acid, which has a conjugated structure and is safe, as the complexing agent, and successfully prepared high-quality silver-graphene (Ag-G) composite coatings with graphene uniformly dispersed in the metal matrix on copper substrates by composite electrodeposition technique. Subsequently, the mechanical properties of composite coatings were investigated by hardness test and X-ray diffractometer, and the tribological properties of the composite coatings and the comprehensive performance under the current carrying conditions were systematically evaluated by using friction and wear tester and load key life tester. The results show that the Ag-G composite coatings have significant advantages in mechanical, tribological, and current carrying conditions. This result not only verifies the feasibility of the design idea of the material, but also provides a new direction for the research and development of electrical contact materials. Full article

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12 pages, 8740 KiB

Open AccessArticle

VO₂-Based Spacecraft Smart Radiator with High Emissivity Tunability and Protective Layer

by Qingjie Xu, Haining Ji, Yang Ren, Yangyong Ou, Bin Liu, Yi Wang, Yongxing Chen, Peng Long, Cong Deng and Jingting Wang

Nanomaterials 2024, 14(16), 1348; https://doi.org/10.3390/nano14161348 - 15 Aug 2024

Viewed by 602

Abstract

In the extreme space environment, spacecraft endure dramatic temperature variations that can impair their functionality. A VO₂-based smart radiator device (SRD) offers an effective solution by adaptively adjusting its radiative properties. However, current research on VO₂-based thermochromic films mainly [...] Read more.

In the extreme space environment, spacecraft endure dramatic temperature variations that can impair their functionality. A VO₂-based smart radiator device (SRD) offers an effective solution by adaptively adjusting its radiative properties. However, current research on VO₂-based thermochromic films mainly focuses on optimizing the emissivity tunability (Δε) of single-cycle sandwich structures. Although multi-cycle structures have shown increased Δε compared to single-cycle sandwich structures, there have been few systematic studies to find the optimal cycle structure. This paper theoretically discusses the influence of material properties and cyclic structure on SRD performance using Finite-Difference Time-Domain (FDTD) software, which is a rigorous and powerful tool for modeling nano-scale optical devices. An optimal structural model with maximum emissivity tunability is proposed. The BaF₂ obtained through optimization is used as the dielectric material to further optimize the cyclic resonator. The results indicate that the tunability of emissivity can reach as high as 0.7917 when the BaF₂/VO₂ structure is arranged in three periods. Furthermore, to ensure a longer lifespan for SRD under harsh space conditions, the effects of HfO₂ and TiO₂ protective layers on the optical performance of composite films are investigated. The results show that when TiO₂ is used as the protective layer with a thickness of 0.1 µm, the maximum emissivity tunability reaches 0.7932. Finally, electric field analysis is conducted to prove that the physical mechanism of the smart radiator device is the combination of stacked Fabry–Perot resonance and multiple solar reflections. This work not only validates the effectiveness of the proposed structure in enhancing spacecraft thermal control performance but also provides theoretical guidance for the design and optimization of SRDs for space applications. Full article

(This article belongs to the Special Issue Advances in Nanomaterials for Optoelectronics: Second Edition)

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Optimal SRD structure with maximum emissivity tunability. Full article ">Figure 2
The single-cycle sandwich structure and the light propagation when VO2 is in the metallic state (a) and dielectric state (b), where df and ds represent the thicknesses of the VO2 and spacer, respectively. Full article ">Figure 3
Emission tunability (Δε) as functions of the thicknesses of VO2 and three dielectric layer materials, (a) Al2O3, (b) ZnS, and (c) BaF2. Full article ">Figure 4
The IR emittance of high/low temperatures and the emissivity tunability (Δε) of the VO2-based two-period structure varies with the thickness of the first VO2 layer (a), the second VO2 layer (b), the first BaF2 layer (c) and the second BaF2 layer (d). Full article ">Figure 5
The IR emittance of high/low temperatures and the emissivity tunability of the VO2-based three-period structure varies with the thickness of the VO2 layer (a–c); the IR emittance of high/low temperatures and the emissivity tunability of the VO2-based three-period structure varies with the thickness of the BaF2 layer (d–f). Full article ">Figure 6
The emissivity tunability of the optimized three-period VO2-based structure with protective layers (HfO2 or TiO2), where the red dashed line indicates the maximum Δε without a protective layer. Full article ">Figure 7
The IR emittance of a three-period structure with a protective layer varies with wavelength at both metallic and dielectric states. Full article ">Figure 8
The normalized electric field |E/E0| is shown for metallic (a,b) and dielectric (c,d) states at wavelengths of 2.9527 and 17.67 µm. E0 represents the incident electric field, directed perpendicular to each layer. The white lines represent the boundaries of each layer. In the figures, the air, TiO2, and BaF2 layers are clearly visible, while the VO2 layer is too thin to be represented. Full article ">

18 pages, 2148 KiB

Open AccessArticle

Nebivolol Polymeric Nanoparticles-Loaded In Situ Gel for Effective Treatment of Glaucoma: Optimization, Physicochemical Characterization, and Pharmacokinetic and Pharmacodynamic Evaluation

by Pradeep Singh Rawat, Punna Rao Ravi, Mohammed Shareef Khan, Radhika Rajiv Mahajan and Łukasz Szeleszczuk

Nanomaterials 2024, 14(16), 1347; https://doi.org/10.3390/nano14161347 - 14 Aug 2024

Viewed by 513

Abstract

Nebivolol hydrochloride (NEB), a 3rd-generation beta-blocker, was recently explored in managing open-angle glaucoma due to its mechanism of action involving nitric oxide release for the vasodilation. To overcome the issue of low ocular bioavailability and the systemic side effects associated with conventional ocular [...] Read more.

Nebivolol hydrochloride (NEB), a 3rd-generation beta-blocker, was recently explored in managing open-angle glaucoma due to its mechanism of action involving nitric oxide release for the vasodilation. To overcome the issue of low ocular bioavailability and the systemic side effects associated with conventional ocular formulation (aqueous suspension), we designed and optimized polycaprolactone polymeric nanoparticles (NEB-PNPs) by applying design of experiments (DoE). The particle size and drug loading of the optimized NEB-PNPs were 270.9 ± 6.3 nm and 28.8 ± 2.4%, respectively. The optimized NEB-PNPs were suspended in a dual-sensitive in situ gel prepared using a mixture of P407 + P188 (as a thermo-sensitive polymer) and κCRG (as an ion-sensitive polymer), reported previously by our group. The NEB-PNPs-loaded in situ gel (NEB-PNPs-ISG) formulation was characterized for its rheological behavior, physical and chemical stability, in vitro drug release, and in vivo efficacy. The NEB-PNPs-loaded in situ gel, in ocular pharmacokinetic studies, achieved higher aqueous humor exposure (AUC_0–t = 329.2 ng × h/mL) and for longer duration (mean residence time = 9.7 h) than compared to the aqueous suspension of plain NEB (AUC_0–t = 189 ng × h/mL and mean residence time = 6.1 h) reported from our previous work. The pharmacokinetic performance of NEB-PNPs-loaded in situ gel translated into a pharmacodynamic response with 5-fold increase in the overall percent reduction in intraocular pressure by the formulation compared to the aqueous suspension of plain NEB reported from our previous work. Further, the mean response time of NEB-PNPs-loaded in situ gel (12.4 ± 0.6 h) was three times higher than aqueous suspension of plain NEB (4.06 ± 0.3 h). Full article

(This article belongs to the Topic Advances in Controlled Release and Targeting of Drugs)

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Figure 1
Three dimensional plots demonstrating the impact of significant factors on critical responses: (a) PS and (b) DL (%) for optimized NEB-PNPs. Full article ">Figure 2
SEM image of the optimized NEB-PNPs. Full article ">Figure 3
Semi-logarithmic plot of loss tangent versus temperature of the formulations. A—blank ISG; B—NEB-PNPs-ISG; and C—NEB-PNPs-ISG in the presence of STF. Full article ">Figure 4
Drug-release profiles of NEB suspension, NEB-PNPs-Susp, and NEB-PNPs-ISG in the in vitro studies. The mean (±SD) of three replicate formulations (n = 3) is presented at each sampling point. Note: Data of NEB-Susp are from our previous published work [<a href="#B3-nanomaterials-14-01347" class="html-bibr">3</a>]. Full article ">Figure 5
Mean concentration of NEB versus time profiles constructed from the ocular administration of NEB-PNPs-Susp, NEB-PNPs-ISG, and NEB-Susp in aqueous humor. Note: Data of NEB-Susp are reproduced from our previous reported work [<a href="#B3-nanomaterials-14-01347" class="html-bibr">3</a>]. Full article ">Figure 6
Percent reduction in intra-ocular pressure (ΔIOP (%)) versus time plot of NEB-PNPs-Susp and NEB-PNPs-ISG administered through ocular route in rabbits (n = 6). Note: NEB-Susp profile is reproduced from our previous reported work [<a href="#B3-nanomaterials-14-01347" class="html-bibr">3</a>]. Full article ">

32 pages, 44965 KiB

Open AccessArticle

Hybrid Cellulosic Substrates Impregnated with Meta-PBI-Stabilized Carbon Nanotubes/Plant Extract-Synthesized Zinc Oxide—Antibacterial and Photocatalytic Dye Degradation Study

by Hristo Penchev, Katerina Zaharieva, Silvia Dimova, Georgy Grancharov, Petar D. Petrov, Maria Shipochka, Ognian Dimitrov, Irina Lazarkevich, Stephan Engibarov and Rumyana Eneva

Nanomaterials 2024, 14(16), 1346; https://doi.org/10.3390/nano14161346 - 14 Aug 2024

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Abstract

Novel fibrous cellulosic substrates impregnated with meta-polybenzimidazole (PBI)-stabilized carbon nanotubes/zinc oxide with different weight content of ZnO and with the use of dimethylacetamide as dispersant media. The pristine ZnO nanoparticle powder was prepared by plant extract-mediated synthesis using Vaccinium vitis-idaea L. The green [...] Read more.

Novel fibrous cellulosic substrates impregnated with meta-polybenzimidazole (PBI)-stabilized carbon nanotubes/zinc oxide with different weight content of ZnO and with the use of dimethylacetamide as dispersant media. The pristine ZnO nanoparticle powder was prepared by plant extract-mediated synthesis using Vaccinium vitis-idaea L. The green synthesized ZnO possesses an average crystallite size of 15 nm. The formation of agglomerates from ZnO NPs with size 250 nm–350 nm in the m-PBI@CNTs/ZnO was determined. The prepared materials were investigated by PXRD analysis, XPS, SEM, EDS, AFM, and TEM in order to establish the phase and surface composition, structure, and morphology of the hybrids. The potential of the synthesized hybrid composites to degrade methylene blue (MB) dye as a model contaminant in aqueous solutions under UV illumination was studied. The photocatalytic results show that in the course of the photocatalytic reaction, the m-PBI@CNTs/ZnO 1:3 photocatalyst leads to the highest degree of degradation of the methylene blue dye (67%) in comparison with the other two studied m-PBI@CNTs/ZnO 1:1 and 1:2 composites (48% and 41%). The antibacterial activity of ZnO nanoparticles and the hybrid CNT materials was evaluated by the RMDA and the dynamic contact method, respectively. The profound antibacterial effect of the m-PBI@CNTs/ZnO hybrids was monitored for 120 h of exposition in dark and UV illumination regimes. The photocatalytic property of ZnO nanoparticles significantly shortens the time for bactericidal action of the composites in both regimes. The m-PBI@CNTs/ZnO 1:2 combination achieved complete elimination of 5.10⁵ CFU/mL E. coli cells after 10 min of UV irradiation. Full article

(This article belongs to the Special Issue Semiconductor-Based Nanomaterials for Photocatalytic Applications—2nd Edition)

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15 pages, 3626 KiB

Open AccessArticle

Optical Fiber Probe with Integrated Micro-Optical Filter for Raman and Surface-Enhanced Raman Scattering Sensing

by Md Abdullah Al Mamun, Tomas Katkus, Anita Mahadevan-Jansen, Saulius Juodkazis and Paul R. Stoddart

Nanomaterials 2024, 14(16), 1345; https://doi.org/10.3390/nano14161345 - 14 Aug 2024

Viewed by 643

Abstract

Optical fiber Raman and surface-enhanced Raman scattering (SERS) probes hold great promise for in vivo biosensing and in situ monitoring of hostile environments. However, the silica Raman scattering background generated within the optical fiber increases in proportion to the length of the fiber, [...] Read more.

Optical fiber Raman and surface-enhanced Raman scattering (SERS) probes hold great promise for in vivo biosensing and in situ monitoring of hostile environments. However, the silica Raman scattering background generated within the optical fiber increases in proportion to the length of the fiber, and it can swamp the signal from the target analyte. While filtering can be applied at the distal end of the fiber, the use of bulk optical elements has limited probe miniaturization to a diameter of 600 µm, which in turn limits the potential applications. To overcome this limitation, femtosecond laser micromachining was used to fabricate a prototype micro-optical filter, which was directly integrated on the tip of a 125 µm diameter double-clad fiber (DCF) probe. The outer surface of the microfilter was further modified with a nanostructured, SERS-active, plasmonic film that was used to demonstrate proof-of-concept performance with thiophenol as a test analyte. With further optimization of the associated spectroscopic system, this ultra-compact microprobe shows great promise for Raman and SERS optical fiber sensing. Full article

(This article belongs to the Special Issue Current Advances in Nanoelectronics, Nanosensors and Devices (Second Edition)—Low Dimensional Materials Fabrication, Characterization and Applications)

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Figure 1

Figure 1
Schematic of the microfilter assembly on the DCF tip. Filter coatings are deposited onto both sides of a UV-grade fused silica substrate. A ring of the short-pass coating is ablated out to the diameter of the inner cladding, leaving an island at the center that blocks Raman-scattered light from the single/few-mode core. The LPF on the second side of the glass substrate has a hole drilled into the axis of the core to pass the clean laser excitation and reduce the intensity of Rayleigh-scattered light from the sample that returns to the inner cladding. Depending on the transmission characteristics of the sample, a second glass plate can be used to allow the Raman-scattered light from the sample to completely fill the aperture of the inner cladding. The SERS substrate is deposited onto the spacer plate as required. Full article ">Figure 2
Schematic illustration of the sequence of fabrication steps used to form the double-sided microfilter assembly for use on a DCF fiber tip (figure not to scale). (a) A commercially available LPF was used as the starting point (see text for details). (b) The glass substrate was ground down and polished to reduce the thickness of the substrate to approximately 0.7 mm. (c) The SPF was deposited onto the opposing surface to the long-pass coating. (d) A ring of SPF was removed through femtosecond laser drilling, after which (e) the hole in the LPF was drilled as described in the text. (f) Finally, a further glass spacer was bonded to the LPF surface to provide a substrate for the SERS sensing surface. (g) Perspective view of the filter patterns. (h) Scanning electron microscope image of SERS-active, photochemically deposited silver nanoparticles on the surface of the outer glass substrate. Full article ">Figure 3
Tool paths programmed for ablating (a) the short-pass coating and (b) the long-pass coating. For the SERS testing presented below, R1 = 5 µm and R2 = 55 µm were used. The spacing and number of paths in each case were determined by the laser spot size (4.5 μm), the track overlap (1.5 μm), and the depth to be ablated. Full article ">Figure 4
Translation stages and UV curing system used for aligning and attaching the microfilter assembly to the DCF tip. Full article ">Figure 5
The double-sided filter combines the transmission characteristics of both the long- and short-pass filters. The SPF (black line) passes the laser line (shown in green) while blocking the silica Raman-scattered signal in the Raman spectral range. To enter the inner cladding of the DCF, Raman-scattered light from the sample passes through the LPF (red line) and through the ablated region of the short-pass coating, while Rayleigh scattering from the sample is blocked. Full article ">Figure 6
(a) Optical profilometer measurement of a typical short-pass island (R1 = 8 µm) and ablated ring after cleaning. (b) Magnified view of the short-pass island region from (a). (c) Microscopic image of another example with R1 = 5 µm, taken under white light epi-illumination (20× objective). Wavelengths above 520 nm are transmitted by the LPF on the far side of the plate, while the shorter, mainly blue wavelengths are reflected, resulting in the observed blue color of the ablated region. (d) SEM image of the short-pass island from (c), with the edges of the island showing some evidence of the discrete layers deposited to form the SPF. The ablated region is accurate to the design dimensions, and the boundaries between the ablated region and the remaining SPF are relatively narrow. While the circumferential tool path from <a href="#nanomaterials-14-01345-f003" class="html-fig">Figure 3</a>a can be discerned here in (c), and individual ablation sites can be seen on the glass surface in (d), there is no sign of any significant residual filter coating material on the ablated surface. Full article ">Figure 7
(a) Spectrum acquired through a 25 cm DCF segment with integrated microfilter assembly. (b) The characteristic SERS peaks of thiophenol are clearly visible after subtracting the fiber Raman background, which is generated primarily by the transmitted laser excitation in this simplified setup. The thiophenol spectrum could not be detected in any of the DCF probes without filtering assembly. (c) As expected, the intensity of the fiber Raman background scales approximately proportionally with the probe length, whereas the SERS peak intensity is reasonably constant with relatively minor losses for longer probe lengths. Peak intensities have been normalized against the 12 cm DCF probe in each case. Full article ">

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Nanomaterials, Volume 14, Issue 16 (August-2 2024) – 54 articles

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