Applied Nanoscience最新文献

This comprehensive study focuses on Gd³⁺ substituted Mn-Cd nanoferrites, represented by the chemical formula Mn_0.3Cd_0.7Gd_xFe_2-xO₄ (MCGF). The dopant ion used was Gd³⁺, with x values ranging from 0.000 to 0.025. We prepared the samples for this research and conducted an extensive analysis using XRD, FTIR, TEM, SEM, and SAED techniques. The XRD patterns confirmed the presence of a spinel structure. Notably, the average crystallite size determined from the XRD analysis was between 32 and 36 nm, which aligns with the results from the TEM analysis. Additionally, the lattice parameters increased with the substitution of the metal ion (Gd³⁺), clearly demonstrating the effect of doping on the structure of the material. The examination of the dielectric properties provided crucial insights: both the dielectric constant (ε’) and dielectric loss (ε") increased with temperature. This is linked to the enhanced sample polarization and suggests that higher temperatures promote dipole relaxation, resulting in an increased dielectric loss. Samples exhibiting significant dielectric losses are particularly valuable for electromagnetic interference shielding applications. We also explored the AC conductivity of the samples and analyzed the relationship between the conductivity and frequency for various doping levels. This investigation offers insights into the behavior of materials at different doping levels and temperatures. The discussion on how the AC conductivity increases with temperature and frequency is particularly intriguing, given the material behavior. Furthermore, we examined the frequency dependency of the real part Z’ and imaginary part Z’’ of the impedance and provided detailed plots. The Nyquist plots and observed relaxation phenomena are crucial for understanding the electrical characteristics of materials. Gas detectors, storage devices, and other devices that can be developed from these synthesized materials are important for modern technologies.

This experimental study examines the characterization and efficacy of modified Zinc Oxide nanoparticles (ZnO NPs), enhanced using a low-level continuous-mode laser at a wavelength of 405 nm, for the control of worker and soldier castes of the termite species Macrotermes malaccensis (Holmgren). The ZnO NP samples were divided into three treatment groups: un-irradiated, 15-min irradiated, and 30-min irradiated. Laser irradiation was conducted using a 405 nm diode laser (THS-1220, China) at a power output of 500 mW, with a beam spot size of 4.0 mm and a fixed distance of 10 cm from the sample surface. Termites were exposed to serial dilutions of the ZnO NP treatments. Statistical analysis revealed a significant difference in mortality rates among the treatment groups (F_(6,36) = 4.75, (p<) 0.05). Notably, the 30-min irradiated ZnO NPs at a concentration of 1 mg/mL resulted in 100% mortality within 36 h. While both irradiated treatments demonstrated significantly higher efficacy than the control, there was no significant difference in mortality rates between the 15- and 30-min irradiated groups. These findings suggest that laser modified ZnO nanoparticles, when used at the appropriate wavelength and power, offer a promising and effective approach for termite control.

Commercial wet wipes were used as an inexpensive template to create zinc oxide (ZnO) and copper oxide (CuO) nanoparticles (NPs) by the combustion technique. Regulated nucleation and growth were made possible by the steady precursor adsorption provided by the fibrous network of wipes. While surface and elemental analysis revealed distinctive morphological features, particle size distribution, and high purity, X-ray analysis verified the formation of phase-pure crystalline ZnO and CuO. Reduced band gaps (2.60 eV for ZnO and 1.90 eV for CuO) were found by UV-Vis absorption analyses, which were explained by defects related to oxygen vacancies during the templating process. CuO outperformed ZnO at higher dosages in the 2,2-Diphenyl-1-picrylhydrazyl (DPPH) assay, which showed concentration-dependent radical scavenging activity. There were notable dose-dependent inhibitory zones in the antibacterial efficacy against S. aureus and E. coli. In a concentration-dependent manner, ZnO and CuO NPs both prevented S. aureus and E. coli from forming biofilms. These results demonstrate the creative use of commercial wipes as long-term templates for the production of functional NPs with intriguing antibacterial properties.

Plant-derived bioactive compounds have garnered significant interest due to their potent therapeutic benefits, including antimicrobial, anti-inflammatory, and anticancer activities. However, their clinical application is hampered by inherent drawbacks such as poor solubility, chemical instability, and lack of multifunctionality in conventional formulations. Addressing these limitations, we report the green synthesis of a multifunctional nanocomposite composed of curcumin (phytochemical), chitosan (biopolymer), aloe vera (natural stabilizer), and graphite nanosheets (nanocarbon reinforcement) aimed at combined infection control and liver cancer therapy. The nanocomposite exhibited hydrodynamic sizes in the range of approximately 700 to 850 nm and demonstrated a positive surface charge (+ 51.1 mV), indicative of high colloidal stability. Fourier Transform Infrared (FTIR) Spectroscopy analysis confirmed successful integration of each component through characteristic functional groups. Biological evaluations revealed potent antimicrobial activity against clinically relevant pathogens such as Staphylococcus aureus and Candida albicans, alongside significant anti-inflammatory effects exemplified by membrane stabilization and hemolysis inhibition in erythrocyte assays. Crucially, the nanocomposite showed dose-dependent cytotoxicity toward HepG2 liver carcinoma cells (IC₅₀ ≈ 60 µg/mL), with associated apoptotic morphological changes. The synergistic assembly of phytochemicals, biosafe polymers, and nanocarbons into a single eco-friendly platform offers a promising approach to effectively address oxidative stress, microbial infections, and tumor progression, positioning this nanocomposite as a sustainable candidate for future biomedical applications.

The study investigates the therapeutic potential of Acacia catechu, a medicinal plant, in the context of inflammatory bowel disease, specifically Crohn’s disease. Utilizing a rat model, the research evaluates the protective effects of both standard extracts and nano formulations of Acacia catechu against colonic damage induced by dextran sulfate sodium. The methodology includes extracting active compounds from the bark of Acacia catechu, followed by pharmacological assessments of antioxidant enzyme activities and histopathological evaluations. Results indicate that the standard extract and nano formulation significantly improve colon health, as evidenced by enhanced colon weight-to-length ratios, better stool consistency, and reduced tissue damage compared to control groups. The antioxidant properties of Acacia catechu, attributed to its bioactive compounds, play a crucial role in mitigating oxidative stress and inflammation. The study highlights the potential of nano formulations of Acacia catechu to enhance the bioavailability of these compounds, suggesting a promising avenue for developing effective treatments for Inflammatory bowel disease. Overall, the findings support the integration of Acacia catechu into therapeutic strategies for managing chronic inflammatory conditions, warranting further research to validate these effects in human populations.

This study conducts a comprehensive analysis of the noise characteristics of a heterojunction double gate ferroelectric p-n-i-n tunnel field-effect transistor (HJ DG Fe p-n-i-n TFET), focusing on generation-recombination (G-R), flicker (1/f), and diffusion noise components, while modulating the thickness of the ferroelectric layer in the gate stack at various operating frequencies. This research relies on the output current noise power spectral density (S_ID) and the input voltage noise power spectral density (S_VG) derived from TCAD simulation approach. This study also examines the effects of both donor and acceptor ITCs, along with the influence of changes in temperature on the noise characteristics of the device. The analysis indicates that G-R noise predominates in the very low frequency range, while flicker noise is prevalent in the low to mid frequency range, with diffusion noise components becoming more pronounced in high frequency domains. A comparison is made between the S_ID and S_VG of several noise components of the proposed device and existing state-of-the-art TFET devices. Furthermore, this study provides an important finding for lowering noise components using ferroelectric material in the gate stack, which is preferable for high-end analog, digital along with various IoT applications.

Superparamagnetic iron oxide nanoparticles (SPIONs) have gained attention as a very promising theragnostic nano-drug delivery systems having inherent antimicrobial potential. Loading pharmacological agents such as curcumin onto these nanocarriers offers a novel strategy to address multidrug-resistant (MDR) bacterial infections. In this study, a multifunctional nanoplatform was developed by engineering curcumin-loaded mesoporous silica-coated SPIONs (CUR-mSiO₂-SPIONs) for combating MDR pathogens and their biofilms. The nanoparticles were systematically characterized for their structural, optical, magnetic, and colloidal properties, confirming successful synthesis and functionalization. The nanocarriers exhibited pH-responsive curcumin release (pH 5.5 and 7.4), favoring the acidic microenvironment to combat against bacterial infections. CUR-mSiO₂-SPIONs shows synergistic enhancement of curcumin’s activity when it is delivered leading to effective growth inhibition and strong biofilm suppression of the MDR pathogens. Mechanistic investigations further indicated that the nanoparticles promoted excessive reactive oxygen species generation and cell wall membrane disruption, ultimately leading to cell death, contributing to their potent antibacterial action. Overall, these findings provide clear evidence of the potential of CUR-mSiO₂-SPIONs as an efficient nanotherapeutic approach for the treatment of biofilm-associated MDR infections.

Present investigation presents a synergistic approach that involved green synthesis and pulsed laser ablation in liquid (PLAL) in order to accomplish ultra-pure and stable copper oxide nanoparticles (CuO NPs) with improved biological prospect. Two methods were used in the synthesis of CuO nanoparticles; (i) PLAL method at wavelengths of light in deionized water, and (ii) PLAL technique using Hibiscus sabdariffa extract as it contains phytochemicals which has potential as a capping and stabilizing agents.

The structural and morphological characterizations of the synthesized CuO crystalline nanomaterials were analyzed by X-ray diffraction (XRD) and field-emission scanning electron microscopy (FE-SEM), which revealed the formation of the nanosized CuO with both methods. However, there was a significant difference in the particle size and distribution. Plant extract-free CuO NPs had an average size of 23.0±18.9 nm and a broad range of sizes. On the other hand, nanobeads with a smaller and more uniform size were obtained in green-assisted PLAL, and by taking the average as 16.6±10.5 nm of diameter. This size decrease and better uniformity indicate that phytochemicals play a regulatory function in nucleation and prevent extensive growth of particles.

EDS (Energy-dispersive X-ray spectroscopy) further verified the elemental components of these samples. Although Cu and O were the main elements in extract-free PLAL samples, green-synthesized NPs had extra biological components from plant extracts, which proved the bio-based capping layer at surface of particles.

Antimicrobial screening indicates noticeable differences in antibacterial activity. The CuO NPs produced without extract showed a zone of inhibition diameter of 12.3±0.6 mm against Staphylococcus aureus and Klebsiella pneumoniae. While those formed by green were bearing inhibition zone each equal of 9.3±0.6 mm and 9.0±1.0 mm, respectively. The green synthesized nanoparticles also exhibited significant antibacterial activity at a concentration slightly below that of chemical agents, apparently due to the surface immobilization of phytochemicals and altered physico-chemical properties.

In conclusion, the study demonstrates the promising prospects of integrating PLAL with plant-based extracts towards sustainable development of bioactive NPs. This dual-method strategy not only provides precise control over nanoparticle size, stability, and surface chemistry, but also can lessen the dependence on chemical reagents. This green synthetic route holds strong potential for the preparation of CuO-based materials in antimicrobial and other biological applications.

This paper presents a comprehensive study of third-order optical nonlinearity in nanostructured Ag/Au composite films coated with Al₂O₃ dielectric layers of varying thickness. Using Z-scanning, performed in both nanosecond (1064 and 532 nm) and femtosecond (800, 600, and 400 nm) modes of laser excitation, the coefficients of nonlinear refraction n₂, nonlinear absorption coefficients β, and saturation intensity I_s were determined. In the nanosecond mode, a change in the sign of n₂ was observed depending on the thickness of the dielectric layer, which is explained by the competition between thermal nonlinearity and electronic contribution, as well as the tunneling of hot carriers through an ultra-thin Al₂O₃ layer. In the femtosecond mode, the nonlinear response was exclusively electronic, with maximum values of n₂ and β observed at 400 nm due to interband excitation in gold and local plasmonic amplification. Increasing the thickness of the Al₂O₃ layer affected the degree of electromagnetic field localization and the efficiency of nonlinear absorption. The results obtained demonstrate that nanoscale structuring of the dielectric environment allows controlling not only the magnitude but also the sign of χ⁽³⁾, which opens up prospects for the creation of tunable nonlinear photonic elements – optical limiters, switches, and modulators.

Fast-track advancements in wearable devices are being driven by the growing demand for real-time monitoring of human activities and health metrics. In this work, a flexible piezoresistive sensor based on carbon nanotube-infused three-dimensional porous PDMS sponges is presented, fabricated using a scalable and robust method. This study distinguishes itself from previous CNT-based sponge research by systematically optimizing CNT content to enhance sensor sensitivity under various strain levels and also using the combination of porogens with different pore sizes for fabrication of the sponges. Detailed characterization of the composite structures was performed using Raman spectroscopy, X-ray diffraction, and field emission scanning electron microscopy. The optimized sponge demonstrates improved gauge factor values of ~ 8, even at a low concentration of 0.25% CNTs, outperforming those reported in the literature for such a minimal concentration. The sensor exhibits an excellent response/recovery time of 0.12 s/0.17 s, respectively. The optimized CNT–PDMS sponge, configured with defined dimensions and stable electrical contacts, exhibited reliable and reproducible electromechanical responses during real-time tracking of both vigorous and subtle motions, confirming its suitability for advanced wearable sensing applications.