Nanomaterials

11 pages, 3801 KiB

Open AccessArticle

Effect of Bias Voltage on the Microstructure and Photoelectric Properties of W-Doped ZnO Films

by Haijuan Mei, Wanli Wang, Junfeng Zhao, Weilong Zhong, Muyi Qiu, Jiayang Xu, Kailin Gao, Ge Liu, Jianchu Liang and Weiping Gong

Nanomaterials 2024, 14(24), 2050; https://doi.org/10.3390/nano14242050 (registering DOI) - 21 Dec 2024

Abstract

W-doped ZnO (WZO) films were deposited on glass substrates by using RF magnetron sputtering at different substrate bias voltages, and the relationships between microstructure and optical and electrical properties were investigated. The results revealed that the deposition rate of WZO films first decreased [...] Read more.

W-doped ZnO (WZO) films were deposited on glass substrates by using RF magnetron sputtering at different substrate bias voltages, and the relationships between microstructure and optical and electrical properties were investigated. The results revealed that the deposition rate of WZO films first decreased from 8.8 to 7.1 nm/min, and then increased to 11.5 nm/min with the increase in bias voltage. After applying a bias voltage to the substrate, the bombardment effect of sputtered ions was enhanced, and the films transformed from a smooth surface into a compact and rough surface. All the films exhibited a hexagonal wurtzite structure with a strong (002) preferred orientation and grew along the c-axis direction. When the bias voltage increased, both the residual stress and lattice parameter of the films gradually increased, and the maximum grain size of 43.4 nm was achieved at −100 V. When the bias voltage was below −300 V, all the films exhibited a high average transmittance of ~90% in the visible light region. As the bias voltage increased, the sheet resistance and resistivity of the films initially decreased and then gradually increased. The highest F_OM of 5.8 × 10⁻⁴ Ω⁻¹ was achieved at −100 V, possessing the best comprehensive photoelectric properties. Full article

(This article belongs to the Special Issue Design and Applications of Heterogeneous Nanostructured Materials)

2 pages, 158 KiB

Open AccessEditorial

Editorial for Special Issue: “Thin Films Based on Nanocomposites (2nd Edition)”

by Marcela Socol and Nicoleta Preda

Nanomaterials 2024, 14(24), 2049; https://doi.org/10.3390/nano14242049 (registering DOI) - 21 Dec 2024

Abstract

The continuous demand for multifunctional materials in industrial applications has driven the design of nanocomposites with new or enhanced properties [...] Full article

(This article belongs to the Special Issue Thin Films Based on Nanocomposites (2nd Edition))

19 pages, 3905 KiB

Open AccessArticle

Engineering n-Type and p-Type BiOI Nanosheets: Influence of Mannitol on Semiconductor Behavior and Photocatalytic Activity

by Shuo Yang, Wenhui Li, Kaiyue Li, Ping Huang, Yuquan Zhuo, Keyan Liu, Ziwen Yang and Donglai Han

Nanomaterials 2024, 14(24), 2048; https://doi.org/10.3390/nano14242048 (registering DOI) - 21 Dec 2024

Abstract

Photocatalytic technology holds significant promise for sustainable development and environmental protection due to its ability to utilize renewable energy sources and degrade pollutants efficiently. In this study, BiOI nanosheets (NSs) were synthesized using a simple water bath method with varying amounts of mannitol [...] Read more.

Photocatalytic technology holds significant promise for sustainable development and environmental protection due to its ability to utilize renewable energy sources and degrade pollutants efficiently. In this study, BiOI nanosheets (NSs) were synthesized using a simple water bath method with varying amounts of mannitol and reaction temperatures to investigate their structural, morphological, photoelectronic, and photocatalytic properties. Notably, the introduction of mannitol played a critical role in inducing a transition in BiOI from an n-type to a p-type semiconductor, as evidenced by Mott–Schottky (M-S) and band structure analyses. This transformation enhanced the density of holes (h⁺) as primary charge carriers and resulted in the most negative conduction band (CB) position (−0.822 V vs. NHE), which facilitated the generation of superoxide radicals (·O^2-) and enhanced photocatalytic activity. Among the samples, the BiOI-0.25-60 NSs (synthesized with 0.25 g of mannitol at 60 °C) exhibited the highest performance, characterized by the largest specific surface area (24.46 m²/g), optimal band gap energy (2.28 eV), and efficient photogenerated charge separation. Photocatalytic experiments demonstrated that BiOI-0.25-60 NSs achieved superior methylene blue (MB) degradation efficiency of 96.5% under simulated sunlight, 1.14 times higher than BiOI-0-70 NSs. Additionally, BiOI-0.25-60 NSs effectively degraded tetracycline (TC), 2,4-dichlorophenol (2,4-D), and rhodamine B (Rh B). Key factors such as photocatalyst concentration, MB concentration, and solution pH were analyzed, and the BiOI-0.25-60 NSs demonstrated excellent recyclability, retaining over 94.3% of their activity after three cycles. Scavenger tests further identified ·O^2- and h⁺ as the dominant active species driving the photocatalytic process. In this study, the pivotal role of mannitol in modulating the semiconductor characteristics of BiOI nanomaterials is underscored, particularly in promoting the n-type to p-type transition and enhancing photocatalytic efficiency. These findings provide a valuable strategy for designing high-performance p-type photocatalysts for environmental remediation applications. Full article

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

14 pages, 2267 KiB

Open AccessArticle

Pressure-Induced Assembly of Organic Phase-Change Materials Hybridized with Expanded Graphite and Carbon Nanotubes for Direct Solar Thermal Harvesting and Thermoelectric Conversion

by Jie Ji, Yizhe Liu, Xiaoxiang Li, Yangzhe Xu, Ting Hu, Zhengzheng Li, Peng Tao and Tao Deng

Nanomaterials 2024, 14(24), 2047; https://doi.org/10.3390/nano14242047 (registering DOI) - 21 Dec 2024

Abstract

Direct harvesting of abundant solar thermal energy within organic phase-change materials (PCMs) has emerged as a promising way to overcome the intermittency of renewable solar energy and pursue high-efficiency heating-related applications. Organic PCMs, however, generally suffer from several common shortcomings including melting-induced leakage, [...] Read more.

Direct harvesting of abundant solar thermal energy within organic phase-change materials (PCMs) has emerged as a promising way to overcome the intermittency of renewable solar energy and pursue high-efficiency heating-related applications. Organic PCMs, however, generally suffer from several common shortcomings including melting-induced leakage, poor solar absorption, and low thermal conductivity. Compounding organic PCMs with single-component carbon materials faces the difficulty in achieving optimized comprehensive performance enhancement. Herein, this work reports the employment of hybrid expanded graphite (EG) and carbon nanotubes (CNTs) to simultaneously realize leakage-proofness, high solar absorptance, high thermal conductivity, and large latent heat storage capacity. The PCM composites were prepared by directly mixing commercial high-temperature paraffin (HPA) powders, EG, and CNTs, followed by subsequent mechanical compression molding. The HPA-EG composites loaded with 20 wt% of EG could effectively suppress melting-induced leakage. After further compounding with 1 wt% of CNTs, the form-stable HPA-EG20-CNT1 composites achieved an axial and in-plane thermal conductivity of 4.15 W/m K and 18.22 W/m K, and a melting enthalpy of 165.4 J/g, respectively. Through increasing the loading of CNTs to 10 wt% in the top thin layer, we further prepared double-layer HPA-EG-CNT composites, which have a high surface solar absorptance of 92.9% for the direct conversion of concentrated solar illumination into storable latent heat. The charged composites could be combined with a thermoelectric generator to release the stored latent heat and generate electricity, which could power up small electric devices such as light-emitting diodes. This work demonstrates the potential for employing hybrid fillers to optimize the thermophysical properties and solar thermal harvesting performances of organic PCMs. Full article

(This article belongs to the Special Issue Nano-Based Advanced Thermoelectric Design)

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18 pages, 2423 KiB

Open AccessReview

Electron Holography for Advanced Characterization of Permanent Magnets: Demagnetization Field Mapping and Enhanced Precision in Phase Analysis

by Sujin Lee

Nanomaterials 2024, 14(24), 2046; https://doi.org/10.3390/nano14242046 (registering DOI) - 20 Dec 2024

Abstract

This review explores a method of visualizing a demagnetization field (H_d) within a thin-foiled Nd₂Fe₁₄B specimen using electron holography observation. Mapping the H_d is critical in electron holography as it provides the only information on [...] Read more.

This review explores a method of visualizing a demagnetization field (H_d) within a thin-foiled Nd₂Fe₁₄B specimen using electron holography observation. Mapping the H_d is critical in electron holography as it provides the only information on magnetic flux density. The H_d map within a Nd₂Fe₁₄B thin foil, derived from this method, showed good agreement with the micromagnetic simulation result, providing valuable insights related to coercivity. Furthermore, this review examines the application of the wavelet hidden Markov model (WHMM) for noise suppression in thin-foiled Nd₂Fe₁₄B crystals. The results show significant suppression of artificial phase jumps in the reconstructed phase images due to the poor visibility of electron holograms under the narrowest fringe spacing required for spatial resolution in electron holography. These techniques substantially enhance the precision of phase analysis and are applicable to a wide range of magnetic materials, enabling more accurate magnetic characterization. Full article

(This article belongs to the Special Issue Exploring Nanomaterials through Electron Microscopy and Spectroscopy)

18 pages, 1019 KiB

Open AccessArticle

Bacterial Outer Membrane Vesicle (OMV)-Encapsulated TiO₂ Nanoparticles: A Dual-Action Strategy for Enhanced Radiotherapy and Immunomodulation in Oral Cancer Treatment

by Shun-An Kan, Li-Wen Zhang, Yu-Chi Wang, Cheng-Yu Chiang, Mei-Hsiu Chen, Shih-Hao Huang, Ming-Hong Chen and Tse-Ying Liu

Nanomaterials 2024, 14(24), 2045; https://doi.org/10.3390/nano14242045 (registering DOI) - 20 Dec 2024

Abstract

Oral squamous-cell carcinoma (OSCC) poses significant treatment challenges due to its high recurrence rates and the limitations of current therapies. Titanium dioxide (TiO₂) nanoparticles are promising radiosensitizers, while bacterial outer membrane vesicles (OMVs) are known for their immunomodulatory properties. This study [...] Read more.

Oral squamous-cell carcinoma (OSCC) poses significant treatment challenges due to its high recurrence rates and the limitations of current therapies. Titanium dioxide (TiO₂) nanoparticles are promising radiosensitizers, while bacterial outer membrane vesicles (OMVs) are known for their immunomodulatory properties. This study investigates the potential of OMV-encapsulated TiO₂ nanoparticles (TiO₂@OMV) to combine these effects for improved OSCC treatment. TiO₂ nanoparticles were synthesized using a hydrothermal method and encapsulated within OMVs derived from Escherichia coli. The TiO₂@OMV carriers were evaluated for their ability to enhance radiosensitivity and stimulate immune responses in OSCC cell lines. Reactive oxygen species (ROS) production, macrophage recruitment, and selective cytotoxicity toward cancer cells were assessed. TiO₂@OMV demonstrated significant radiosensitization and immune activation compared to unencapsulated TiO₂ nanoparticles. The system selectively induced cytotoxicity in OSCC cells, sparing normal cells, and enhanced ROS generation and macrophage-mediated antitumor responses. This study highlights TiO₂@OMV as a dual-action therapeutic platform that synergizes radiotherapy and immunomodulation, offering a targeted and effective strategy for OSCC treatment. The approach could improve therapeutic outcomes and reduce the adverse effects associated with conventional therapies. Full article

(This article belongs to the Section Biology and Medicines)

12 pages, 2474 KiB

Open AccessArticle

Flexible and Stable GaN Piezoelectric Sensor for Motion Monitoring and Fall Warning

by Zhiling Chen, Kun Lv, Renqiang Zhao, Yaxian Lu and Ping Chen

Nanomaterials 2024, 14(24), 2044; https://doi.org/10.3390/nano14242044 - 20 Dec 2024

Abstract

Wearable devices have potential applications in health monitoring and personalized healthcare due to their portability, conformability, and excellent mechanical flexibility. However, their performance is often limited by instability in acidic or basic environments. In this study, a flexible sensor with excellent stability based [...] Read more.

Wearable devices have potential applications in health monitoring and personalized healthcare due to their portability, conformability, and excellent mechanical flexibility. However, their performance is often limited by instability in acidic or basic environments. In this study, a flexible sensor with excellent stability based on a GaN nanoplate was developed through a simple and controllable fabrication process, where the linearity and stability remained at almost 99% of the original performance for 40 days in an air atmosphere. Moreover, perfect stability was also demonstrated in acid–base environments, with pH values ranging from 1 to 13. Based on its excellent stability and piezotronic performance, a flexible device for motion monitoring was developed, capable of detecting motions such as finger, knee, and wrist bending, as well as swallowing. Furthermore, gesture recognition and intelligent fall monitoring were explored based on the bending properties. In addition, an intelligent fall warning system was proposed for the personalized healthcare application of elders by applying machine learning to analyze data collected from typical activities. Our research provides a path for stable and flexible electronics and personalized healthcare applications. Full article

(This article belongs to the Section Nanoelectronics, Nanosensors and Devices)

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12 pages, 5835 KiB

Open AccessArticle

Formation and Magnetic Properties of Transition Metal Atomic Chains on Monolayer MoS₂ Grain Boundaries: A First-Principles Study

by Zhiyuan Li, Shuqing Yang and Yiren Wang

Nanomaterials 2024, 14(24), 2043; https://doi.org/10.3390/nano14242043 - 20 Dec 2024

Abstract

Magnetic one-dimensional nanostructures show great potential in spintronics and can be used as basic building blocks for magnetic materials and devices with multiple functions. In this study, transition group atomic chains (V, Cr, Mn, Fe, Co, and Ni) are introduced into nonmagnetic MoS [...] Read more.

Magnetic one-dimensional nanostructures show great potential in spintronics and can be used as basic building blocks for magnetic materials and devices with multiple functions. In this study, transition group atomic chains (V, Cr, Mn, Fe, Co, and Ni) are introduced into nonmagnetic MoS₂ with a 4|8ud-type grain boundary. Based on first-principles calculations, the V atomic chains show good thermodynamic stability and can self-assemble along the grain boundary direction. The formation of V, Cr, Mn, and Ni atomic chains can induce magnetism into a 4|8ud-type MoS₂ system through typical d-d and p-d interactions. This joint effect of transition metal doping and grain boundaries on the magnetism of monolayer MoS₂ is of great significance for exploring the electromagnetic properties of monolayer MoS₂ for the development of electronic devices. Full article

(This article belongs to the Special Issue Theoretical Calculation Study of Nanomaterials: 2nd Edition)

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14 pages, 26016 KiB

Open AccessArticle

Electrodeposition of Nanostructured Metals on n-Silicon and Insights into Rhodium Deposition

by Giulio Pappaianni, Francesco Montanari, Marco Bonechi, Giovanni Zangari, Walter Giurlani and Massimo Innocenti

Nanomaterials 2024, 14(24), 2042; https://doi.org/10.3390/nano14242042 - 20 Dec 2024

Abstract

In this study, we investigate the electrodeposition of various metals on silicon. Mn, Co, Ni, Ru, Pd, Rh, and Pt were identified as promising candidates for controlled electrodeposition onto silicon. Electrochemical evaluations employing cyclic voltammetry, Scanning Electron Microscopy (SEM) associated with energy-dispersive X-Ray [...] Read more.

In this study, we investigate the electrodeposition of various metals on silicon. Mn, Co, Ni, Ru, Pd, Rh, and Pt were identified as promising candidates for controlled electrodeposition onto silicon. Electrochemical evaluations employing cyclic voltammetry, Scanning Electron Microscopy (SEM) associated with energy-dispersive X-Ray Spectroscopy (SEM-EDS), and X-Ray Photoelectron Spectroscopy (XPS) techniques confirmed the deposition of Pd, Rh, and Pt as nanoparticles. Multi-cycle charge-controlled depositions were subsequently performed to evaluate the possibility of achieving tunable electrodeposition of nanostructured rhodium on n-doped silicon. The procedure increased surface coverage from 9% to 84%, with the average particle size diameter ranging from 57 nm to 168 nm, and with an equivalent thickness of the deposits up to 43.9 nm, varying the number of charge-controlled deposition cycles. The electrodeposition of rhodium on silicon presents numerous opportunities across various scientific and technological domains, driving innovation and enhancing the performance of devices and materials used in catalysis, electronics, solar cells, fuel cells, and sensing. Full article

(This article belongs to the Special Issue Heterogeneous Integration Technology for More Moore)

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9 pages, 4545 KiB

Open AccessArticle

Study of Thermalization Mechanisms of Hot Carriers in BABr-Added MAPbBr₃ for the Top Layer of Four-Junction Solar Cells

by Yi Zhang, Huilong Chen, Junfeng Qu, Jiayu Zhang and Gavin Conibeer

Nanomaterials 2024, 14(24), 2041; https://doi.org/10.3390/nano14242041 - 19 Dec 2024

Abstract

The hot carrier multi-junction solar cell (HCMJC) is an advanced-concept solar cell with a theoretical efficiency greater than 65%. It combines the advantages of hot carrier solar cells and multi-junction solar cells with higher power conversion efficiency (PCE). The thermalization coefficient (Q [...] Read more.

The hot carrier multi-junction solar cell (HCMJC) is an advanced-concept solar cell with a theoretical efficiency greater than 65%. It combines the advantages of hot carrier solar cells and multi-junction solar cells with higher power conversion efficiency (PCE). The thermalization coefficient (Q_th) has been shown to slow down by an order of magnitude in low-dimensional structures, which will significantly improve PCE. However, there have been no studies calculating the Q_th of MAPbBr₃ quantum dots so far. In this work, the Q_th values of MAPbBr₃ quantum dots and after BABr addition were calculated based on power-dependent steady-state photoluminescence (PD-SSPL). Their peak positions in PD-SSPL increased from 2.37 to 2.71 eV after adding BABr. The fitting shows that, after adding BABr, the Q_th decreased from 2.64 ± 0.29 mW·K⁻¹·cm⁻² to 2.36 ± 0.25 mW·K⁻¹·cm⁻², indicating a lower relaxation rate. This is because BABr passivates surface defects, slowing down the carrier thermalization process. This work lays the foundation for the theoretical framework combining perovskite materials, which suggests that the appropriate passivation of BABr has the potential to further reduce Q_th and make MAPbBr₃ QDs with BABr modified more suitable as the top absorption layer of HCMJCs. Full article

(This article belongs to the Special Issue Optoelectronic Properties of Nanomaterials and Their Applications in Advanced Concept Solar Cells)

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11 pages, 2610 KiB

Open AccessArticle

Controllable Synthesis of Three-Dimensional Chiral Au Nanoflowers Induced by Cysteine with Excellent Biocompatible Properties

by Shengmiao Liu, Jianhao Zhang and Wenjing Yan

Nanomaterials 2024, 14(24), 2040; https://doi.org/10.3390/nano14242040 - 19 Dec 2024

Abstract

Chiral molecules are ubiquitous in nature and biological systems, where the unique optical and physical properties of chiral nanoparticles are closely linked to their shapes. Synthesizing chiral plasmonic nanomaterials with precise structures and tunable sizes is essential for exploring their applications. This study [...] Read more.

Chiral molecules are ubiquitous in nature and biological systems, where the unique optical and physical properties of chiral nanoparticles are closely linked to their shapes. Synthesizing chiral plasmonic nanomaterials with precise structures and tunable sizes is essential for exploring their applications. This study presents a method for growing three-dimensional chiral gold nanoflowers (Au NFs) derived from trisoctahedral (TOH) nanocrystals using D-cysteine and L-cysteine as chiral inducers. By employing a two-step seed-mediated growth approach, stable chiral Au nanoparticles with customizable sizes, shapes, and optical properties were produced by adjusting the Au nanosphere (Au NP) seed concentration and cysteine dosage. These nanoparticles exhibited optical activity in both the visible and near-infrared regions, with a maximum anisotropy factor (g-factor) of 0.024. Furthermore, the PEG-modified chiral Au NFs demonstrated excellent biocompatibility. This approach provides a precise method for geometrically controlling the design of three-dimensional chiral nanomaterials, holding great potential for biomedical applications. Full article

(This article belongs to the Special Issue The Synthesis of Antibacterial Nanomaterials and Their Biomedical Applications)

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13 pages, 4086 KiB

Open AccessArticle

Surface Microstructure Enhanced Cryogenic Infrared Light Emitting Diodes for Semiconductor Broadband Upconversion

by Peng Bai, Hanbin Wang, Rongrong Lv, Yi Wang, Yinqiao Li, Shangjie Han, Jiaxuan Cai, Ning Yang, Weidong Chu, Yan Xie, Meng Chen, Yingxin Wang and Ziran Zhao

Nanomaterials 2024, 14(24), 2039; https://doi.org/10.3390/nano14242039 - 19 Dec 2024

Abstract

Broadband upconversion has various applications in solar photovoltaic, infrared and terahertz detection imaging, and biomedicine. The low efficiency of the light-emitting diodes (LEDs) limits the broadband upconversion performance. In this paper, we propose to use surface microstructures to enhance the electroluminescence efficiency (ELE) [...] Read more.

Broadband upconversion has various applications in solar photovoltaic, infrared and terahertz detection imaging, and biomedicine. The low efficiency of the light-emitting diodes (LEDs) limits the broadband upconversion performance. In this paper, we propose to use surface microstructures to enhance the electroluminescence efficiency (ELE) of LEDs. Systematical investigations on the cryogenic-temperature performances of microstructure-coupled LEDs, including electroluminescence efficiency, luminescence spectrum, and recombination rate, have been carried out by elaborating their enhancement mechanism and light emitting characteristics both experimentally and theoretically. We have revealed that the reason for the nearly 35% ELE enhancement of the optimized structure under cryogenic temperature and weak injection current is the efficient carrier injection efficiency and the high recombination rate in the active region. We also compare studies of the surface luminescence uniformity of the optimized LED with that of the unoptimized device. This work gives a precise description, and explanation of the performance of the optimized microstructure coupled LED at low temperatures, providing important guidance and inspiration for the optimization of broadband upconverter in the cryogenic temperature region. Full article

(This article belongs to the Special Issue Study on Photoelectric Properties and Applications of Nanostructured Materials)

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14 pages, 2036 KiB

Open AccessArticle

New Label-Free DNA Nanosensor Based on Top-Gated Metal–Ferroelectric–Metal Graphene Nanoribbon on Insulator Field-Effect Transistor: A Quantum Simulation Study

by Khalil Tamersit, Abdellah Kouzou, José Rodriguez and Mohamed Abdelrahem

Nanomaterials 2024, 14(24), 2038; https://doi.org/10.3390/nano14242038 - 19 Dec 2024

Abstract

In this paper, a new label-free DNA nanosensor based on a top-gated (TG) metal–ferroelectric–metal (MFM) graphene nanoribbon field-effect transistor (TG-MFM GNRFET) is proposed through a simulation approach. The DNA sensing principle is founded on the dielectric modulation concept. The computational method employed to [...] Read more.

In this paper, a new label-free DNA nanosensor based on a top-gated (TG) metal–ferroelectric–metal (MFM) graphene nanoribbon field-effect transistor (TG-MFM GNRFET) is proposed through a simulation approach. The DNA sensing principle is founded on the dielectric modulation concept. The computational method employed to evaluate the proposed nanobiosensor relies on the coupled solutions of a rigorous quantum simulation with the Landau–Khalatnikov equation, considering ballistic transport conditions. The investigation analyzes the effects of DNA molecules on nanodevice behavior, encompassing potential distribution, ferroelectric-induced gate voltage amplification, transfer characteristics, subthreshold swing, and current ratio. It has been observed that the feature of ferroelectric-induced gate voltage amplification using the integrated MFM structure can significantly enhance the biosensor’s sensitivity to DNA molecules, whether in terms of threshold voltage shift or drain current variation. Additionally, we propose the current ratio as a sensing metric due to its ability to consider all DNA-induced modulations of electrical parameters, specifically the increase in on-state current and the decrease in off-state current and subthreshold swing. The obtained results indicate that the proposed negative-capacitance GNRFET-based DNA nanosensor could be considered an intriguing option for advanced point-of-care testing. Full article

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

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19 pages, 4132 KiB

Open AccessArticle

Exposure to a Titanium Dioxide Product Alters DNA Methylation in Human Cells

by Carlos Wells, Marta Pogribna, Arjun Sharmah, Angel Paredes, Beverly Word, Anil K. Patri, Beverly Lyn-Cook and George Hammons

Nanomaterials 2024, 14(24), 2037; https://doi.org/10.3390/nano14242037 - 19 Dec 2024

Abstract

The safety of titanium dioxide (TiO₂), widely used in foods and personal care products, has been of ongoing concern. Significant toxicity of TiO₂ has been reported, suggesting a risk to human health. To evaluate its potential epigenotoxicity, the effect of [...] Read more.

The safety of titanium dioxide (TiO₂), widely used in foods and personal care products, has been of ongoing concern. Significant toxicity of TiO₂ has been reported, suggesting a risk to human health. To evaluate its potential epigenotoxicity, the effect of exposure to a TiO₂ product to which humans could be exposed on DNA methylation, a primary epigenetic mechanism, was investigated using two human cell lines (Caco-2 (colorectal) and HepG2 (liver)) relevant to human exposure. Global methylation was determined by enzyme-linked immunosorbent assay-based immunochemical analysis. Gene promoter methylation was evaluated using EpiTect Methyl II Signature PCR System Array technology. Expression of DNA methyltransferases, MBD2, and URHF1 was quantified by qRT-PCR. A decrease in global DNA methylation was observed in both cell lines. Across the cell lines, seven genes (BNIP3, DNAJC15, GADD45G, GDF15, INSIG1, SCARA3, and TP53) were identified in which promoters were methylated. Changes in promoter methylation were associated with gene expression. Results also revealed aberrant expression of regulatory genes, DNA methyltransferases, MBD2, and UHRF1. Findings from the study clearly demonstrate the impact of TiO₂ exposure on DNA methylation in two cell types, supporting the potential involvement of this epigenetic mechanism in its biological responses. Hence, epigenetic studies are critical for complete assessment of potential risk from exposure. Full article

(This article belongs to the Special Issue Nanosafety and Nanotoxicology: Current Opportunities and Challenges)

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12 pages, 2570 KiB

Open AccessArticle

Multifunctional SERS Chip for Biological Application Realized by Double Fano Resonance

by Weile Zhu, Huiyang Wang, Yuheng Wang, Shengde Liu, Jianglei Di and Liyun Zhong

Nanomaterials 2024, 14(24), 2036; https://doi.org/10.3390/nano14242036 - 19 Dec 2024

Abstract

The in situ and label-free detection of molecular information in biological cells has always been a challenging problem due to the weak Raman signal of biological molecules. The use of various resonance nanostructures has significantly advanced Surface-enhanced Raman spectroscopy (SERS) in signal enhancement [...] Read more.

The in situ and label-free detection of molecular information in biological cells has always been a challenging problem due to the weak Raman signal of biological molecules. The use of various resonance nanostructures has significantly advanced Surface-enhanced Raman spectroscopy (SERS) in signal enhancement in recent years. However, biological cells are often immersed in different formulations of culture medium with varying refractive indexes and are highly sensitive to the temperature of the microenvironment. This necessitates that SERS meets the requirements of refractive index insensitivity, low thermal damage, broadband enhancement, and other needs in addition to signal enhancement. Here, we propose a SERS chip with integrated dual Fano resonance and the corresponding analytical model. This model can be used to quickly lock the parameters and then analyze the performance of the dual resonance SERS chip. The simulation and experimental characterization results demonstrate that the integrated dual Fano resonances have the ability for independent broadband tuning. This capability enhances both the excitation and radiation processes of Raman signals simultaneously, ensuring that the resonance at the excitation wavelength is not affected by the culture medium (the refractive index) and reduces heat generation. Furthermore, the dual Fano resonance modes can synergize with each other to greatly enhance both the amplitude and enhanced range of the Raman signal, providing a stable, reliable, and comprehensive detection tool and strategy for fingerprint signal detection of bioactive samples. Full article

(This article belongs to the Section Biology and Medicines)

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10 pages, 3244 KiB

Open AccessFeature PaperArticle

Study on Electrical and Temperature Characteristics of β-Ga₂O₃-Based Diodes Controlled by Varying Anode Work Function

by Yunlong He, Baisong Sheng, Xiaoli Lu, Guran Chen, Peng Liu, Ying Zhou, Xichen Wang, Weiwei Chen, Lei Wang, Jun Yang, Xuefeng Zheng, Xiaohua Ma and Yue Hao

Nanomaterials 2024, 14(24), 2035; https://doi.org/10.3390/nano14242035 - 18 Dec 2024

Abstract

This study systematically investigates the effects of anode metals (Ti/Au and Ni/Au) with different work functions on the electrical and temperature characteristics of β-Ga₂O₃-based Schottky barrier diodes (SBDs), junction barrier Schottky diodes (JBSDs) and P-N diodes (PNDs), utilizing Silvaco [...] Read more.

This study systematically investigates the effects of anode metals (Ti/Au and Ni/Au) with different work functions on the electrical and temperature characteristics of β-Ga₂O₃-based Schottky barrier diodes (SBDs), junction barrier Schottky diodes (JBSDs) and P-N diodes (PNDs), utilizing Silvaco TCAD simulation software, device fabrication and comparative analysis. From the perspective of transport characteristics, it is observed that the SBD exhibits a lower turn-on voltage and a higher current density. Notably, the V_on of the Ti/Au anode SBD is merely 0.2 V, which is the lowest recorded value in the existing literature. The V_on and current trend of two types of PNDs are nearly consistent, confirming that the contact between Ti/Au or Ni/Au and NiO_x is ohmic. A theoretical derivation reveals the basic principles of the different contact resistances and current variations. With the combination of SBD and PND, the V_on, current density, and variation rate of the JBSD lie between those of the SBD and PND. In terms of temperature characteristics, all diodes can work well at 200 °C, with both current density and V_on showing a decreasing trend as the temperature increases. Among them, the PND with a Ni/Au anode exhibits the best thermal stability, with reductions in V_on and current density of 8.20% and 25.31%, respectively, while the SBD with a Ti/Au anode shows the poorest performance, with reductions of 98.56% and 30.73%. Finally, the reverse breakdown (BV) characteristics of all six devices are tested. The average BV values for the PND with Ti/Au and Ni/Au anodes reach 1575 V and 1550 V, respectively. Moreover, although the V_on of the JBSD decreases to 0.24 V, its average BV is approximately 220 V. This work could provide valuable insights for the future application of β-Ga₂O₃-based diodes in high-power and low-power consumption systems. Full article

(This article belongs to the Special Issue Research of Conductive Nano-Scale Technology Tailored to Semiconductor Industry)

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16 pages, 5472 KiB

Open AccessArticle

Optimization for the Process Parameters of Nickel–Titanium Nitride Composites Fabricated via Jet Pulse Electrodeposition

by Xue Guo, Dehao Tian, Chaoyu Li, Xiang Li, Wei Li, Mengyu Cao, Fengwu Zhang and Baojin Wang

Nanomaterials 2024, 14(24), 2034; https://doi.org/10.3390/nano14242034 - 18 Dec 2024

Abstract

The corrosion resistance of nickel–titanium nitride (Ni/TiN) composites is significantly influenced by the operation parameters during the jet pulse electrodeposition (JPE) process. The effect of current density, jet rate, TiN concentration, and duty cycle impact on the anti-corrosion property of Ni/TiN composites were [...] Read more.

The corrosion resistance of nickel–titanium nitride (Ni/TiN) composites is significantly influenced by the operation parameters during the jet pulse electrodeposition (JPE) process. The effect of current density, jet rate, TiN concentration, and duty cycle impact on the anti-corrosion property of Ni/TiN composites were investigated and optimized using the response surface method (RSM). After the optimization of the operation parameters, the corrosion current of Ni/TiN composites decreased from 9.52 × 10⁻⁵ A/cm² to 4.63 × 10⁻⁵ A/cm². The corrosion current of Ni/TiN composites decreased initially and then increased with an increase in current density, jet rate, TiN concentration, and duty cycle. During the jet electrodeposition process, the influence of the duty cycle on the corrosion current of Ni/TiN composites was comparatively insignificant, whereas the concentration of TiN had a significant effect on the corrosion current. The error rate between the predicted value and the measured result from the corrosion current of Ni/TiN composites was only 0.64%, indicating the high accuracy of fitting the model. Furthermore, X-ray diffraction (XRD) patterns and scanning electron microscope (SEM) images revealed that the optimized Ni/TiN composites comprised significant Ti content, fine nickel gain, and a compact, smooth structure. In addition, the electrochemical measured results demonstrated that the optimized Ni/TiN composites possessed a low self-corrosion current and high self-corrosion potential. These findings show that the optimized composites have a substantially greater corrosion resistance compared to two other unoptimized Ni/TiN composites. Full article

(This article belongs to the Section Nanocomposite Materials)

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9 pages, 6116 KiB

Open AccessCommunication

Influence of Absorber Contents and Temperatures on the Dielectric Properties and Microwave Absorbing Performances of C@TiC/SiO₂ Composites

by Yan Wang, Xin Sun, Zhihe Xiao, Jian Gu, Qinyi Dong, Shuhang Yi and Junyang Jin

Nanomaterials 2024, 14(24), 2033; https://doi.org/10.3390/nano14242033 - 18 Dec 2024

Abstract

TiC provides a promising potential for high-temperature microwave absorbers due to its unique combination of thermal stability, high electrical conductivity, and robust structural integrity. C@TiC/SiO₂ composites were successfully fabricated using a simple blending and cold-pressing method. The effects of C@TiC’s absorbent content [...] Read more.

TiC provides a promising potential for high-temperature microwave absorbers due to its unique combination of thermal stability, high electrical conductivity, and robust structural integrity. C@TiC/SiO₂ composites were successfully fabricated using a simple blending and cold-pressing method. The effects of C@TiC’s absorbent content and temperature on the dielectric and microwave absorption properties of C@TiC/SiO₂ composites were investigated. The addition of C@TiC from 10 wt.% to 30 wt.% not only endows the composites with a higher dielectric constant and dielectric loss, but also with a greater high-temperature stability in terms of dielectric and microwave absorption properties. The composite with 30 wt.%C@TiC demonstrates a strong microwave absorption capability with a minimum reflection loss (RL_min) of −55.87 dB, −48.49 dB, and −40.36 dB at room temperature, 50 °C, and 100 °C, respectively; the 50 wt.%C@TiC composite exhibits an enhanced high-temperature microwave absorption performance with an RL_min of −16.13 dB and −15.72 dB at 200 °C and 300 °C, respectively. This study demonstrates that the TiC-based absorbers present an innovative solution for high-temperature microwave absorption, providing stability, versatility, and adaptability in extreme operational environments. Full article

(This article belongs to the Special Issue Functional Polymer and Ceramic Nanocomposites)

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14 pages, 12358 KiB

Open AccessArticle

Oxygenated VOC Detection Using SnO₂ Nanoparticles with Uniformly Dispersed Bi₂O₃

by Haoyue Yang, Koichi Suematsu, Felipe Hiroshi Mashiba, Ken Watanabe and Kengo Shimanoe

Nanomaterials 2024, 14(24), 2032; https://doi.org/10.3390/nano14242032 - 18 Dec 2024

Abstract

Bi₂O₃ particles are introduced as foreign additives onto SnO₂ nanoparticles (NPs) surfaces for the efficient detection of oxygenated volatile organic compounds (VOCs). Bi₂O₃-loaded SnO₂ materials are prepared via the impregnation method followed by calcination [...] Read more.

Bi₂O₃ particles are introduced as foreign additives onto SnO₂ nanoparticles (NPs) surfaces for the efficient detection of oxygenated volatile organic compounds (VOCs). Bi₂O₃-loaded SnO₂ materials are prepared via the impregnation method followed by calcination treatment. The abundant Bi₂O₃/SnO₂ interfaces are constructed by the uniform dispersion of Bi₂O₃ particles on the SnO₂ surface. The results of oxygen temperature-programmed desorption suggest that Bi₂O₃-loaded SnO₂ samples display improved surface oxygen ions than neat-SnO₂ NPs. As a result, the gas sensor based on 1 mol% Bi₂O₃-loaded SnO₂ (1Bi-L-SnO₂) composites shows significantly higher sensitivity and a faster response speed toward various oxygenated VOCs compared with SnO₂, especially at 200 °C and 250 °C. The results of catalytic combustion and temperature-programmed reaction measurements reveal the dominant role of adsorption and partial oxidation during ethanol combustion on SnO₂ and 1Bi-L-SnO₂ surfaces. In this case, the improvement in the sensing performance of the 1Bi-L-SnO₂ sensor can be associated with the increase in surface oxygen ions at Bi₂O₃/SnO₂ interfaces. The results confirm the significant role of surface functionalization for sensing materials. The obtained outstanding sensing performance provides the potential application for the simultaneous detection of total oxygenated VOCs in practice. Full article

(This article belongs to the Special Issue Nanostructured Materials in Gas Sensing Applications)

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