Nanomaterials

11 pages, 5221 KiB

Open AccessArticle

Green Chemical Shear-Thickening Polishing of Monocrystalline Silicon

by Jiancheng Xie, Feng Shi, Shanshan Wang, Xing Peng and Qun Hao

Nanomaterials 2024, 14(23), 1866; https://doi.org/10.3390/nano14231866 - 21 Nov 2024

A green chemical shear-thickening polishing (GC-STP) method was studied to improve the surface precision and processing efficiency of monocrystalline silicon. A novel green shear-thickening polishing slurry composed of silica nanoparticles, alumina abrasive, sorbitol, plant ash, polyethylene glycol, and deionized water was formulated. The [...] Read more.

A green chemical shear-thickening polishing (GC-STP) method was studied to improve the surface precision and processing efficiency of monocrystalline silicon. A novel green shear-thickening polishing slurry composed of silica nanoparticles, alumina abrasive, sorbitol, plant ash, polyethylene glycol, and deionized water was formulated. The monocrystalline silicon was roughly ground using a diamond polishing slurry and then the GC-STP process. The material removal rate (MRR) during GC-STP was 4.568 μmh⁻¹. The material removal mechanism during the processing of monocrystalline silicon via GC-STP was studied using elemental energy spectroscopy and FTIR spectroscopy. After 4 h of the GC-STP process, the surface roughness (Ra) of the monocrystalline silicon wafer was reduced to 0.278 nm, and an excellent monocrystalline silicon surface quality was obtained. This study shows that GC-STP is a green, efficient, and low-damage polishing method for monocrystalline silicon. Full article

(This article belongs to the Special Issue New Perspectives in Ultra Precision Manufacturing and Micro-Nano Inspection Technology)

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22 pages, 5794 KiB

Open AccessArticle

Hydrothermal and Co-Precipitation Combined with Photo-Reduced Preparation of Ag/AgBr/MgBi₂O₆ Composites for Visible Light Degradation Toward Organics

by Hsin-Yi Huang, Mudakazhi Kanakkithodi Arun, Sabu Thomas, Mei-Yao Wu, Tsunghsueh Wu and Yang-Wei Lin

Nanomaterials 2024, 14(23), 1865; https://doi.org/10.3390/nano14231865 (registering DOI) - 21 Nov 2024

Abstract

This study developed a MgBi₂O₆-based photocatalyst via low-temperature hydrothermal synthesis. AgBr was co-precipitated onto MgBi₂O₆, and silver nanoparticles (AgNPs) were photo-reduced onto the surface. The photocatalytic performance, assessed by methylene blue (MB) degradation under white-light [...] Read more.

This study developed a MgBi₂O₆-based photocatalyst via low-temperature hydrothermal synthesis. AgBr was co-precipitated onto MgBi₂O₆, and silver nanoparticles (AgNPs) were photo-reduced onto the surface. The photocatalytic performance, assessed by methylene blue (MB) degradation under white-light LED irradiation (2.5 W, power density = 0.38 W/cm²), showed that Ag/AgBr/MgBi₂O₆ achieved 98.6% degradation in 40 min, outperforming MgBi₂O₆ (37.5%) and AgBr/MgBi₂O₆ (85.5%). AgNPs boosted electron-hole separation via surface plasmon resonance, reducing recombination. A Z-scheme photocatalytic mechanism was suggested, where photogenerated carriers transferred across the p–n heterojunction between AgBr and MgBi₂O₆, producing reactive oxygen species like superoxide and hydroxyl radicals critical for dye degradation. Thus, the Ag/AgBr/MgBi₂O₆ composites possessed excellent photocatalytic performance regarding dyestuff degradation (85.8–99.9% degradation within 40 min) under white-light LED irradiation. Full article

(This article belongs to the Special Issue Hybrid Nanomaterials and/or Nanocomposites for Photo(Electro-) Catalytic Applications)

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15 pages, 4314 KiB

Open AccessArticle

TCAD Simulation of Resistive Switching Devices: Impact of ReRAM Configuration on Neuromorphic Computing

by Seonggyeom Kim and Jonghwan Lee

Nanomaterials 2024, 14(23), 1864; https://doi.org/10.3390/nano14231864 - 21 Nov 2024

Abstract

This paper presents a method for modeling ReRAM in TCAD and validating its accuracy for neuromorphic systems. The data obtained from TCAD are used to analyze the accuracy of the neuromorphic system. The switching behaviors of ReRAM are implemented using the kinetic Monte [...] Read more.

This paper presents a method for modeling ReRAM in TCAD and validating its accuracy for neuromorphic systems. The data obtained from TCAD are used to analyze the accuracy of the neuromorphic system. The switching behaviors of ReRAM are implemented using the kinetic Monte Carlo (KMC) approach. Realistic ReRAM characteristics are obtained through the use of the trap-assisted tunneling (TAT) model and thermal equations. HfO₂-Al₂O₃-based ReRAM offers improved switching behaviors compared to HfO₂-based ReRAM. The variation in conductance depends on the structure of the ReRAM. The conductance extracted from TCAD is validated in the neuromorphic system using the MNIST (Modified National Institute of Standards and Technology) dataset. Full article

(This article belongs to the Special Issue Nanoelectronics: Materials, Devices and Applications (Second Edition))

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13 pages, 5766 KiB

Open AccessArticle

First Principles Study of p-Type Transition and Enhanced Optoelectronic Properties of g-ZnO Based on Diverse Doping Strategies

by Kaiqi Bao, Yanfang Zhao, Wei Ding, Yuanbin Xiao and Bing Yang

Nanomaterials 2024, 14(23), 1863; https://doi.org/10.3390/nano14231863 - 21 Nov 2024

Abstract

By utilizing first principles calculations, p-type transition in graphene-like zinc oxide (g-ZnO) through elemental doping was achieved, and the influence of different doping strategies on the electronic structure, energy band structure, and optoelectronic properties of g-ZnO was investigated. This research study delves into [...] Read more.

By utilizing first principles calculations, p-type transition in graphene-like zinc oxide (g-ZnO) through elemental doping was achieved, and the influence of different doping strategies on the electronic structure, energy band structure, and optoelectronic properties of g-ZnO was investigated. This research study delves into the effects of strategies such as single-acceptor doping, double-acceptor co-doping, and donor–acceptor co-doping on the properties of g-ZnO. This study found that single-acceptor doping with Li and Ag elements can form shallow acceptor levels, thereby facilitating p-type conductivity. Furthermore, the introduction of the donor element F can compensate for the deep acceptor levels formed by double-acceptor co-doping, transforming them into shallow acceptor levels and modulating the energy band structure. The co-doping strategy involving double-acceptor elements and a donor element further optimizes the properties of g-ZnO, such as reducing the bandgap and enhancing carrier mobility. Additionally, in terms of optical properties, g-Zn₁₄Li₂FO₁₅ demonstrates outstanding performance in the visible-light region compared with other doping systems, especially generating a higher absorption peak around the wavelength of 520 nm. These findings provide a theoretical foundation for the application of g-ZnO in optoelectronic devices. Full article

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

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11 pages, 7663 KiB

Open AccessArticle

Visualization of Stress Fiber Formation Induced by Photodynamic Therapy with Porphylipoprotein

by Atsushi Taninaka, Hiromi Kurokawa, Mayuka Kamiyanagi, Osamu Takeuchi, Hirofumi Matsui and Hidemi Shigekawa

Nanomaterials 2024, 14(23), 1862; https://doi.org/10.3390/nano14231862 - 21 Nov 2024

Abstract

We investigated stress fiber formation induced by photodynamic therapy (PDT) with porphylipoprotein (PLP) by observing actin filaments by super-resolution confocal microscopy and measuring the cellular elastic modulus by atomic force microscopy. We identified different intracellular mechanisms of stress fiber formation between RGM1 epithelial [...] Read more.

We investigated stress fiber formation induced by photodynamic therapy (PDT) with porphylipoprotein (PLP) by observing actin filaments by super-resolution confocal microscopy and measuring the cellular elastic modulus by atomic force microscopy. We identified different intracellular mechanisms of stress fiber formation between RGM1 epithelial cells, which were derived from rat gastric mucosa, and RGK1 cells, which were cancer-like mutants of RGM1. Our findings show that when PLP is used as a photosensitizer in PDT, it selectively induces necrosis in tumors with minimal impact on the surrounding normal tissues, as it is less likely to cause blood flow obstruction. Full article

(This article belongs to the Section Biology and Medicines)

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16 pages, 4459 KiB

Open AccessArticle

Novel Spectroscopic Studies of the Interaction of Three Different Types of Iron Oxide Nanoparticles with Albumin

by Silviya Abarova, Tsenka Grancharova, Plamen Zagorchev, Boris Tenchov and Bissera Pilicheva

Nanomaterials 2024, 14(23), 1861; https://doi.org/10.3390/nano14231861 - 21 Nov 2024

Abstract

In the present work, we studied the interactions of three types of iron oxide nanoparticles (IONPs) with human serum albumin (HSA) by fluorescence and UV-Vis spectroscopy. The determined binding parameters of the reactions and the thermodynamic parameters, including ΔHo, ΔSo, and ΔGo indicated [...] Read more.

In the present work, we studied the interactions of three types of iron oxide nanoparticles (IONPs) with human serum albumin (HSA) by fluorescence and UV-Vis spectroscopy. The determined binding parameters of the reactions and the thermodynamic parameters, including ΔHo, ΔSo, and ΔGo indicated that electrostatic forces play a major role in the interaction of IONPs with HSA. These measurements indicate a fluorescent quenching mechanism based on IONPs-HSA static complex formation. Our study shows that the interaction between HSA and IONPs depends on the nanoparticle structure. The interaction between IONPs and HSA was found to be spontaneous, exothermic, and entropy-driven. HSA was shown to interact moderately with IONPs obtained with plant extracts of Uncaria tomentosa L. (IONP@UT) and Clinopodium vulgare L. (IONP@CV), and firmly with IONPs prepared with Ganoderma lingzhi (Reishi) extract (IONP@GL), via ground-state association. Analysis by modified Stern-Volmer approximation indicates that the quenching mechanism is static. Our study significantly improves our understanding of the mechanisms of interaction, distribution, and transport involved in the interaction between proteins and IONPs. It provides crucial insights into the functional perturbations of albumin binding capacity and the effects of IONPs on the stability and structural modifications of plasma carrier proteins. Full article

(This article belongs to the Special Issue Nanostructured Materials for Biological and Pharmaceutical Applications (Second Edition))

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9 pages, 2142 KiB

Open AccessArticle

Lead Catalyzed GaAs Nanowires Grown by Molecular Beam Epitaxy

by Igor V. Shtrom, Nickolai V. Sibirev, Ilya P. Soshnikov, Igor V. Ilkiv, Evgenii V. Ubyivovk, Rodion R. Reznik and George E. Cirlin

Nanomaterials 2024, 14(23), 1860; https://doi.org/10.3390/nano14231860 - 21 Nov 2024

Abstract

This study investigates the growth of gallium arsenide nanowires, using lead as a catalyst. Typically, nanowires are grown through the vapor–solid–liquid mechanism, where a key factor is the reduction in the nucleation barrier beneath the catalyst droplet. Arsenic exhibits limited solubility in conventional [...] Read more.

This study investigates the growth of gallium arsenide nanowires, using lead as a catalyst. Typically, nanowires are grown through the vapor–solid–liquid mechanism, where a key factor is the reduction in the nucleation barrier beneath the catalyst droplet. Arsenic exhibits limited solubility in conventional catalysts; however, this research explores an alternative scenario in which lead serves as a solvent for arsenic, while gallium and lead are immiscible liquids. Liquid lead easily dissolves in Si as well as in GaAs. The preservation of the catalyst during the growth process is also addressed. GaAs nanowires have been grown by molecular beam epitaxy on silicon Si (111) substrates at varying temperatures. Observations indicate the spontaneous doping of the GaAs nanowires with both lead and silicon. These findings contribute to a deeper understanding of the VLS mechanism involved in nanowire growth. They are also an important step in the study of GaAs nanowire-doping processes. Full article

(This article belongs to the Special Issue Preparation and Application of Nanowires: 2nd Edition)

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13 pages, 5136 KiB

Open AccessArticle

Thermal Decomposition of Core–Shell-Structured RDX@AlH₃, HMX@AlH₃, and CL-20@AlH₃ Nanoparticles: Reactive Molecular Dynamics Simulations

by Zijian Sun, Lei Yang, Hui Li, Mengyun Mei, Lixin Ye, Jiake Fan and Weihua Zhu

Nanomaterials 2024, 14(22), 1859; https://doi.org/10.3390/nano14221859 - 20 Nov 2024

Abstract

The reactive molecular dynamics method was employed to examine the thermal decomposition process of aluminized hydride (AlH₃) containing explosive nanoparticles with a core–shell structure under high temperature. The core was composed of the explosives RDX, HMX, and CL-20, while the shell [...] Read more.

The reactive molecular dynamics method was employed to examine the thermal decomposition process of aluminized hydride (AlH₃) containing explosive nanoparticles with a core–shell structure under high temperature. The core was composed of the explosives RDX, HMX, and CL-20, while the shell was composed of AlH₃. It was demonstrated that the CL-20@AlH₃ NPs decomposed at a faster rate than the other NPs, and elevated temperatures could accelerate the initial decomposition of the explosive molecules. The incorporation of aluminized hydride shells did not change the initial decomposition mechanism of the three explosives. The yields of the main products (NO, NO₂, N₂, H₂O, H₂, and CO₂) were investigated. There was a large number of solid aluminized clusters produced during the decomposition, mainly Al_mO_n and Al_mC_n clusters, together with Al_mN_n clusters dispersed in the Al_mO_n clusters. Full article

(This article belongs to the Special Issue Editorial Board Members’ Collection Series: Theory and Simulation of Nanostructures)

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15 pages, 3703 KiB

Open AccessArticle

Tuning Intermediate Band Solar Cell Efficiency: The Interplay of Electric Fields, Composition, Impurities, and Confinement

by Hassan Abboudi, Redouane En-nadir, Mohamed A. Basyooni-M. Kabatas, Ayoub El Baraka, Ilyass Ez-zejjari, Haddou El Ghazi and Ahmed Sali

Nanomaterials 2024, 14(22), 1858; https://doi.org/10.3390/nano14221858 - 20 Nov 2024

Abstract

In this study, we investigated the influence of structural parameters, including active region dimensions, electric field intensity, In-composition, impurity position, and potential profiles, on the energy levels, sub-gap transitions, and photovoltaic characteristics of a p-GaN/i-(In, Ga)N/GaN-n (p-QW-n) structure. The finite element method (FEM) [...] Read more.

In this study, we investigated the influence of structural parameters, including active region dimensions, electric field intensity, In-composition, impurity position, and potential profiles, on the energy levels, sub-gap transitions, and photovoltaic characteristics of a p-GaN/i-(In, Ga)N/GaN-n (p-QW-n) structure. The finite element method (FEM) has been used to solve numerically the Schrödinger equation. We found that particle and sub-gap energy levels are susceptible to well width, electric field, and impurity position. Particle energy decreases with increasing well size and electric field intensity, while impurity position affects energy based on proximity to the well center. Potential profile shapes, such as rectangular (RQW) and parabolic (PQW), also play a significant role, with PQW profiles providing stronger particle confinement. IB width increases with electric field intensity and saturates at higher In-content. Voc increases with field strength but decreases with In-content, and the parabolic profile yields higher efficiency than the rectangular one. Photovoltaic efficiency is improved with an appropriately oriented electric field and decreases with higher In-content and field intensity. These findings highlight the critical role of structural parameters in optimizing QW-IBSC performance. Full article

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16 pages, 4473 KiB

Open AccessArticle

Nano-Silver-Loaded Activated Carbon Material Derived from Waste Rice Noodles: Adsorption and Antibacterial Performance

by Guanzhi Ding, Guangzhi Qin, Wanying Ying, Pengyu Wang, Yang Yang, Chuanyang Tang, Qing Liu, Minghui Li, Ke Huang and Shuoping Chen

Nanomaterials 2024, 14(22), 1857; https://doi.org/10.3390/nano14221857 - 20 Nov 2024

Abstract

This study demonstrates, for the first time, the conversion of waste rice noodles (WRN) into a cost-effective, nano-silver-loaded activated carbon (Ag/AC) material capable of efficient adsorption and antibacterial activity. The fabrication process began with the conversion of WRN into hydrothermal carbon (HTC) via [...] Read more.

This study demonstrates, for the first time, the conversion of waste rice noodles (WRN) into a cost-effective, nano-silver-loaded activated carbon (Ag/AC) material capable of efficient adsorption and antibacterial activity. The fabrication process began with the conversion of WRN into hydrothermal carbon (HTC) via a hydrothermal method. Subsequently, the HTC was combined with silver nitrate (AgNO₃) and sodium hydroxide (NaOH), followed by activation through high-temperature calcination, during which AgNO₃ was reduced to nano-Ag and loaded onto the HTC-derived AC, resulting in a composite material with both excellent adsorption properties and antibacterial activity. The experimental results indicated that the incorporation of nano-Ag significantly enhanced the specific surface area of the Ag/AC composite and altered its pore size distribution characteristics. Under optimized preparation conditions, the obtained Ag/AC material exhibited a specific surface area of 2025.96 m²/g and an average pore size of 2.14 nm, demonstrating effective adsorption capabilities for the heavy metal Cr(VI). Under conditions of pH 2 and room temperature (293 K), the maximum equilibrium adsorption capacity for Cr(VI) reached 97.07 mg/g. The adsorption behavior of the resulting Ag/AC fitted the Freundlich adsorption isotherm and followed a pseudo-second-order kinetic model. Furthermore, the Ag/AC composite exhibited remarkable inhibitory effects against common pathogenic bacteria such as E. coli and S. aureus, achieving antibacterial rates of 100% and 81%, respectively, after a contact time of 4 h. These findings confirm the feasibility of utilizing the HTC method to process WRN and produce novel AC-based functional materials. Full article

(This article belongs to the Section 2D and Carbon Nanomaterials)

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30 pages, 6585 KiB

Open AccessReview

Recent Progress on Advanced Flexible Lithium Battery Materials and Fabrication Process

by Mi Zhou, Daohong Han, Xiangming Cui, Jingzhao Wang, Xin Chen, Jianan Wang, Shiyi Sun and Wei Yan

Nanomaterials 2024, 14(22), 1856; https://doi.org/10.3390/nano14221856 - 20 Nov 2024

Abstract

Flexible energy storage devices have attracted wide attention as a key technology restricting the vigorous development of wearable electronic products. However, the practical application of flexible batteries faces great challenges, including the lack of good mechanical toughness of battery component materials and excellent [...] Read more.

Flexible energy storage devices have attracted wide attention as a key technology restricting the vigorous development of wearable electronic products. However, the practical application of flexible batteries faces great challenges, including the lack of good mechanical toughness of battery component materials and excellent adhesion between components, resulting in battery performance degradation or failure when subjected to different types of deformation. It is imperative to develop flexible batteries that can withstand deformation under different conditions and maintain stable battery performance. This paper reviews the latest research progress of flexible lithium batteries, from the research and development of new flexible battery materials, advanced preparation processes, and typical flexible structure design. First, the types of key component materials and corresponding modification technologies for flexible batteries are emphasized, mainly including carbon-based materials with flexibility, lithium anode materials, and solid-state electrolyte materials. In addition, the application of typical flexible structural designs (buckling, spiral, and origami) in flexible batteries is clarified, such as 3D printing and electrospinning, as well as advanced fabrication techniques commonly used in flexible materials and battery components. Finally, the limitations and coping strategies in the practical application of flexible lithium batteries are discussed, which provides new ideas for future research. Full article

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17 pages, 7201 KiB

Open AccessArticle

Thermal Performance Analysis of a Nonlinear Couple Stress Ternary Hybrid Nanofluid in a Channel: A Fractal–Fractional Approach

by Saqib Murtaza, Nidhal Becheikh, Ata Ur Rahman, Aceng Sambas, Chemseddine Maatki, Lioua Kolsi and Zubair Ahmad

Nanomaterials 2024, 14(22), 1855; https://doi.org/10.3390/nano14221855 - 20 Nov 2024

Abstract

Nanofluids have improved thermophysical properties compared to conventional fluids, which makes them promising successors in fluid technology. The use of nanofluids enables optimal thermal efficiency to be achieved by introducing a minimal concentration of nanoparticles that are stably suspended in conventional fluids. The [...] Read more.

Nanofluids have improved thermophysical properties compared to conventional fluids, which makes them promising successors in fluid technology. The use of nanofluids enables optimal thermal efficiency to be achieved by introducing a minimal concentration of nanoparticles that are stably suspended in conventional fluids. The use of nanofluids in technology and industry is steadily increasing due to their effective implementation. The improved thermophysical properties of nanofluids have a significant impact on their effectiveness in convection phenomena. The technology is not yet complete at this point; binary and ternary nanofluids are currently being used to improve the performance of conventional fluids. Therefore, this work aims to theoretically investigate the ternary nanofluid flow of a couple stress fluid in a vertical channel. A homogeneous suspension of alumina, cuprous oxide, and titania nanoparticles is formed by dispersing trihybridized nanoparticles in a base fluid (water). The effects of pressure gradient and viscous dissipation are also considered in the analysis. The classical ternary nanofluid model with couple stress was generalized using the fractal–fractional derivative (FFD) operator. The Crank–Nicolson technique helped to discretize the generalized model, which was then solved using computer tools. To investigate the properties of the fluid flow and the distribution of thermal energy in the fluid, numerical methods were used to calculate the solution, which was then plotted as a function of various physical factors. The graphical results show that at a volume fraction of 0.04 (corresponding to 4% of the base fluid), the heat transfer rate of the ternary nanofluid flow increases significantly compared to the binary and unary nanofluid flows. Full article

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56 pages, 5775 KiB

Open AccessReview

Gold Nanoparticles in Nanomedicine: Unique Properties and Therapeutic Potential

by Furkan Eker, Emir Akdaşçi, Hatice Duman, Mikhael Bechelany and Sercan Karav

Nanomaterials 2024, 14(22), 1854; https://doi.org/10.3390/nano14221854 - 20 Nov 2024

Abstract

Gold nanoparticles (NPs) have demonstrated significance in several important fields, including drug delivery and anticancer research, due to their unique properties. Gold NPs possess significant optical characteristics that enhance their application in biosensor development for diagnosis, in photothermal and photodynamic therapies for anticancer [...] Read more.

Gold nanoparticles (NPs) have demonstrated significance in several important fields, including drug delivery and anticancer research, due to their unique properties. Gold NPs possess significant optical characteristics that enhance their application in biosensor development for diagnosis, in photothermal and photodynamic therapies for anticancer treatment, and in targeted drug delivery and bioimaging. The broad surface modification possibilities of gold NPs have been utilized in the delivery of various molecules, including nucleic acids, drugs, and proteins. Moreover, gold NPs possess strong localized surface plasmon resonance (LSPR) properties, facilitating their use in surface-enhanced Raman scattering for precise and efficient biomolecule detection. These optical properties are extensively utilized in anticancer research. Both photothermal and photodynamic therapies show significant results in anticancer treatments using gold NPs. Additionally, the properties of gold NPs demonstrate potential in other biological areas, particularly in antimicrobial activity. In addition to delivering antigens, peptides, and antibiotics to enhance antimicrobial activity, gold NPs can penetrate cell membranes and induce apoptosis through various intracellular mechanisms. Among other types of metal NPs, gold NPs show more tolerable toxicity capacity, supporting their application in wide-ranging areas. Gold NPs hold a special position in nanomaterial research, offering limited toxicity and unique properties. This review aims to address recently highlighted applications and the current status of gold NP research and to discuss their future in nanomedicine. Full article

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

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14 pages, 2614 KiB

Open AccessArticle

Synthesis and Characterization of Microcapsules as Fillers for Self-Healing Dental Composites

by Maria Amalia Tăut, Marioara Moldovan, Miuţa Filip, Ioan Petean, Codruţa Saroşi, Stanca Cuc, Adrian Catalin Taut, Ioan Ardelean, Viorica Lazăr and Sorin Claudiu Man

Nanomaterials 2024, 14(22), 1853; https://doi.org/10.3390/nano14221853 - 20 Nov 2024

Abstract

This article proposes the synthesis and characterization of (triethylene glycol dimethacrylate–N,N-dihydroxyethyl-p-toluidine) TEGDMA-DHEPT self-healing microcapsules for their inclusion in dental composite formulations. The obtaining method is the in situ emulsion polymerization of the (poly urea-formaldehyde) (PUF) coatings. The microcapsules were characterized by Fourier transform [...] Read more.

This article proposes the synthesis and characterization of (triethylene glycol dimethacrylate–N,N-dihydroxyethyl-p-toluidine) TEGDMA-DHEPT self-healing microcapsules for their inclusion in dental composite formulations. The obtaining method is the in situ emulsion polymerization of the (poly urea-formaldehyde) (PUF) coatings. The microcapsules were characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), atomic force microscopy (AFM), high-performance liquid chromatography (HPLC), and low-field nuclear magnetic resonance (NMR) techniques. The optimal formation of uniform microcapsules is achieved at a stirring speed of 800 rpm and centrifugation is no longer necessary. HPLC demonstrates that the microcapsules formed at 800 rpm show a better control of liquid release than the heterogeneous ones obtained at a lower stirring speed. The centrifuged samples have rounded shapes, with dimensions between 80 and 800 nm, while the non-centrifuged samples are more uniform, with a spherical shape and dimensions of approximately 800 nm. Full article

(This article belongs to the Section Biology and Medicines)

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10 pages, 2327 KiB

Open AccessArticle

Electric Field-Enhanced SERS Detection Using MoS₂-Coated Patterned Si Substrate with Micro-Pyramid Pits

by Tsung-Shine Ko, Hsiang-Yu Hsieh, Chi Lee, Szu-Hung Chen, Wei-Chun Chen, Wei-Lin Wang, Yang-Wei Lin and Sean Wu

Nanomaterials 2024, 14(22), 1852; https://doi.org/10.3390/nano14221852 - 20 Nov 2024

Abstract

This study utilized semiconductor processing techniques to fabricate patterned silicon (Si) substrates with arrays of inverted pyramid-shaped micro-pits by etching. Molybdenum trioxide (MoO₃) was then deposited on these patterned Si substrates using a thermal evaporation system, followed by two-stage sulfurization in [...] Read more.

This study utilized semiconductor processing techniques to fabricate patterned silicon (Si) substrates with arrays of inverted pyramid-shaped micro-pits by etching. Molybdenum trioxide (MoO₃) was then deposited on these patterned Si substrates using a thermal evaporation system, followed by two-stage sulfurization in a high-temperature furnace to grow MoS₂ thin films consisting of only a few atomic layers. During the dropwise titration of Rhodamine 6G (R6G) solution, a longitudinal electric field was applied using a Keithley 2400 (Cleveland, OH, USA) source meter. Raman mapping revealed that under a 100 mV condition, the analyte R6G molecules were effectively confined within the pits. Due to its two-dimensional structure, MoS₂ provides a high surface area and supports a surface-enhanced Raman scattering (SERS) charge transfer mechanism. The SERS results demonstrated that the intensity in the pits of the few-layer MoS₂/patterned Si SERS substrate was approximately 274 times greater compared to planar Si, with a limit of detection reaching 10⁻⁵ M. The experimental results confirm that this method effectively resolves the issue of random distribution of analyte molecules during droplet evaporation, thereby enhancing detection sensitivity and stability. Full article

(This article belongs to the Special Issue Nanoscale Photonics and Metamaterials)

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17 pages, 2840 KiB

Open AccessArticle

Green Synthesis of Al-ZnO Nanoparticles Using Cucumis maderaspatanus Plant Extracts: Analysis of Structural, Antioxidant, and Antibacterial Activities

by S. K. Johnsy Sugitha, R. Gladis Latha, Raja Venkatesan, Seong-Cheol Kim, Alexandre A. Vetcher and Mohammad Rashid Khan

Nanomaterials 2024, 14(22), 1851; https://doi.org/10.3390/nano14221851 - 20 Nov 2024

Abstract

Nanoparticles derived from biological sources are currently garnering significant interest due to their diverse range of potential applications. The purpose of the study was to synthesize Al-doped nanoparticles of zinc oxide (ZnO) from leaf extracts of Cucumis maderaspatanus and assess their antioxidant and [...] Read more.

Nanoparticles derived from biological sources are currently garnering significant interest due to their diverse range of potential applications. The purpose of the study was to synthesize Al-doped nanoparticles of zinc oxide (ZnO) from leaf extracts of Cucumis maderaspatanus and assess their antioxidant and antimicrobial activity using some bacterial and fungal strains. These nanoparticles were analyzed using X-ray diffraction (XRD), ultraviolet–visible (UV-vis) spectroscopy, Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) with energy dispersive X-ray analysis (EDAX), transmission electron microscopy (TEM), and thermogravimetric analysis/differential thermal analysis (TG-DTA). The average crystalline size was determined to be 25 nm, as evidenced by the XRD analysis. In the UV-vis spectrum, the absorption band was observed around 351 nm. It was discovered that the Al-ZnO nanoparticles had a bandgap of 3.25 eV using the Tauc relation. Furthermore, by FTIR measurement, the presence of the OH group, C=C bending of the alkene group, and C=O stretching was confirmed. The SEM analysis revealed that the nanoparticles were distributed uniformly throughout the sample. The EDAX spectrum clearly confirmed the presence of Zn, Al, and O elements in the Al-ZnO nanoparticles. The TEM results also indicated that the green synthesized Al-ZnO nanoparticles displayed hexagonal shapes with an average size of 25 nm. The doping of aluminum may enhance the thermal stability of the ZnO by altering the crystal structure or phase composition. The observed changes in TG, DTA, and DTG curves reflect the impact of aluminum doping on the structural and thermal properties of ZnO nanoparticles. The antibacterial activity of the Al-ZnO nanoparticles using the agar diffusion method showed that the maximum zone of inhibition has been noticed against organisms of Gram-positive S. aureus compared with Gram-negative E. coli. Moreover, antifungal activity using the agar cup method showed that the maximum zone of inhibition was observed on Aspergilus flavus, followed by Candida albicans. Al-doping nanoparticles increases the number of charge carriers, which can enhance the generation of reactive oxygen species (ROS) under UV light exposure. These ROS are known to possess strong antimicrobial properties. Al-doping can improve the crystallinity of ZnO, resulting in a larger surface area that facilitates more interaction with microbial cells. The structural and biological characteristics of Al-ZnO nanoparticles might be responsible for the enhanced antibacterial activity exhibited in the antibacterial studies. Al-ZnO nanoparticles with Cucumis maderaspatanus leaf extract produced via the green synthesis methods have remarkable antioxidant activity by scavenging free radicals against DPPH radicals, according to these results. Full article

(This article belongs to the Special Issue Antimicrobial and Antioxidant Activity of Nanoparticles)

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14 pages, 578 KiB

Open AccessArticle

Effective Piecewise Mass Distributions for Optimal Energy Eigenvalues of a Particle in Low-Dimensional Heterojunctions

by Josep Batle, Orion Ciftja, Mahmoud Abdel-Aty, Mohamed Ahmed Hafez and Shawkat Alkhazaleh

Nanomaterials 2024, 14(22), 1850; https://doi.org/10.3390/nano14221850 - 20 Nov 2024

Abstract

Systems composed of several multi-layer compounds have been extremely useful in tailoring different quantum physical properties of nanomaterials. This is very much true when it comes to semiconductor materials and, in particular, to heterostructures and heterojunctions. The formalism of a position-dependent effective mass [...] Read more.

Systems composed of several multi-layer compounds have been extremely useful in tailoring different quantum physical properties of nanomaterials. This is very much true when it comes to semiconductor materials and, in particular, to heterostructures and heterojunctions. The formalism of a position-dependent effective mass has proved to be a very efficient tool in those cases where quantum wells emerge either in one or two dimensions. In this work, we use a variety of mathematical theorems, as well as numerical computations, to study different scenarios pertaining to choices of a specific piecewise constant effective mass for a particle that causes its energy eigenvalues to reach an extremum. These results are relevant when it comes to practical technological applications such as modifying the optical energy gap between the first excited state and the ground state energy of the system. At the end of our contribution, we also question the physical validity of some approximations for systems with particles that possess a position-dependent mass especially for those cases in which the mass distribution is divergent. Full article

(This article belongs to the Section Theory and Simulation of Nanostructures)

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18 pages, 5981 KiB

Open AccessArticle

Free-Standing Carbon Nanofiber Films with Supported Cobalt Phosphide Nanoparticles as Cathodes for Hydrogen Evolution Reaction in a Microbial Electrolysis Cell

by Gerard Pérez-Pi, Jorge Luque-Rueda, Pau Bosch-Jimenez, Eduard Borràs Camps and Sandra Martínez-Crespiera

Nanomaterials 2024, 14(22), 1849; https://doi.org/10.3390/nano14221849 - 19 Nov 2024

Abstract

High-performance and cost-efficient electrocatalysts and electrodes are needed to improve the hydrogen evolution reaction (HER) for the hydrogen (H₂) generation in electrolysers, including microbial electrolysis cells (MECs). In this study, free-standing carbon nanofiber (CNF) films with supported cobalt phosphide nanoparticles have [...] Read more.

High-performance and cost-efficient electrocatalysts and electrodes are needed to improve the hydrogen evolution reaction (HER) for the hydrogen (H₂) generation in electrolysers, including microbial electrolysis cells (MECs). In this study, free-standing carbon nanofiber (CNF) films with supported cobalt phosphide nanoparticles have been prepared by means of an up-scalable electrospinning process followed by a thermal treatment under controlled conditions. The produced cobalt phosphide-supported CNF films show to be nanoporous (pore volume up to 0.33 cm³ g⁻¹) with a high surface area (up to 502 m² g⁻¹) and with a suitable catalyst mass loading (up to 0.49 mg cm⁻²). Values of overpotential less than 140 mV at 10 mA cm⁻² have been reached for the HER in alkaline media (1 M KOH), which demonstrates a high activity. The high electrical conductivity together with the mechanical stability of the free-standing CNF films allowed their direct use as cathodes in a MEC reactor, resulting in an exceptionally low voltage operation (0.75 V) with a current density demand of 5.4 A m⁻². This enabled the production of H₂ with an energy consumption below 30 kWh kg⁻¹ H₂, which is highly efficient. Full article

(This article belongs to the Special Issue Hydrogen Production and Evolution Based on Nanocatalysts)

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25 pages, 10477 KiB

Open AccessArticle

Portable Homemade Magnetic Hyperthermia Apparatus: Preliminary Results

by Teresa Castelo-Grande, Paulo A. Augusto, Lobinho Gomes, Eduardo Calvo and Domingos Barbosa

Nanomaterials 2024, 14(22), 1848; https://doi.org/10.3390/nano14221848 - 19 Nov 2024

Abstract

This study aims to describe and evaluate the performance of a new device for magnetic hyperthermia that can produce an alternating magnetic field with adjustable frequency without the need to change capacitors from the resonant bank, as required by other commercial devices. This [...] Read more.

This study aims to describe and evaluate the performance of a new device for magnetic hyperthermia that can produce an alternating magnetic field with adjustable frequency without the need to change capacitors from the resonant bank, as required by other commercial devices. This innovation, among others, is based on using a capacitator bank that dynamically adjusts the frequency. To validate the novel system, a series of experiments were conducted using commercial magnetic nanoparticles (MNPs) demonstrating the device’s effectiveness and allowing us to identify new challenges associated with the design of more powerful devices. A computational model was also used to validate the device and to allow us to determine the best system configuration. The results obtained are consistent with those from other studies using the same MNPs but with magnetic hyperthermia commercial equipment, confirming the good performance of the developed device (e.g., consistent SAR values between 1.37 and 10.80 W/gMNP were obtained, and experiments reaching temperatures above 43 °C were also obtained). This equipment offers additional advantages, including being economical, user-friendly, and portable. Full article

(This article belongs to the Special Issue New Insights into the Therapeutic Efficacy of Nanomaterials)

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