Applied Nanoscience最新文献

This study investigates the influence of thermal treatment on the antimicrobial properties of silver nanoparticles NPs Ag⁰ deposited on a macroporous Silochrome. The research focuses on the morphological and distributional changes of the nanoparticles under elevated temperatures and their subsequent impact on antibacterial activity. The results demonstrate that increasing the treatment temperature reduces nanoparticle size and enhances their distribution on the silica surface, significantly improving antimicrobial efficacy. The immobilization of Ag⁺ cations from a solution and the incorporation of reduced NPs Ag⁰ onto the silica surface resulted in a homogeneous distribution of nanoparticles around mesopores and imparted antibacterial properties. The critical role of the acid–base centers of SiO₂ in the antibacterial activity of SiO₂/Ag⁰ nanostructures was established, and conditions for optimizing this activity were determined by altering the size and localization of NPs Ag⁰ through thermal treatment at 500 °C, which reduced the minimum inhibitory concentration by six-to-seven times. These findings highlight the potential of thermal treatment as a viable method for optimizing the antimicrobial performance of SiO₂-based nanocomposites.

This research examines the thermal behavior of Al₂O₃-based nanofluids in multilayer microchannel heat sink (MCHS) using both simulation and experimental approaches. The examinations were carried out considering three distinct nanofluid concentrations viz 0.5, 1.0, and 2.0% volume and mass flux values from 0.01 to 0.05 kg/s. Observations demonstrated that an increase in concentration enhances heat transfer performance, with Nusselt numbers ranging 112.0 at 2.0% concentration results, considering that the influence of mass flow rate on the heat dissipation coefficient rose sharply and heat transfer coefficient reached the maximum of 270.8 W/m²·K. As a consequence of it, the pressure drop that accompanied enhanced performance increased to 600 Pa in similar circumstances. This work optimizes Al₂O₃ nanofluids in multilayer MCHS, boosting heat transfer to 270.8 W/m²·K while controlling pressure drop. The optimal 1.5% concentration at 0.04 kg/s offers efficient, scalable cooling solutions for electronics, automotive, and industrial applications. This research also utilized a multi-objective optimization strategy that determined proper operating conditions that would result in both thermal efficiency and pumping power. From these findings, it is evident that Al₂O₃ nanofluids can be used in enhanced cooling applications, and researchers and engineers in the industrial and manufacturing sectors can use them in enhancing their cooling systems designs and parameters.

The increasing incidence of skin cancer, antimicrobial resistance, and oxidative stress-related conditions necessitates the development of multifunctional therapeutic agents. The main objectives of this investigation is synthesis, characterization, and biomedical assessment of silver nanoparticles (AgNPs) synthesized via a modified Turkevich method using trisodium citrate and SDS as reducing and capping agents. Characterization through ultraviolet–visible (UV–Vis) spectroscopy, X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, zeta potential analysis, and field-emission scanning electron microscopy (FE-SEM) confirmed the successful formation of stable, spherical AgNPs with sizes ranging from 21.99 to 41.35 nm and a moderately stable surface charge (− 27.24 mV). Biological evaluations demonstrated the dose-dependent cytotoxicity of AgNPs against A375 melanoma skin cancer cells, with significant reduction in cell viability at higher concentrations. Antibacterial assessment against Staphylococcus aureus (S. aureus) revealed strong, concentration-dependent inhibition zones, highlighting the AgNPs potential in combating resistant skin infections. Additionally, AgNPs exhibited noteworthy antioxidant activity in DPPH assays, although slightly lower than standard ascorbic acid. The results suggest that the synthesized AgNPs possess potent triple-functional activity, including anticancer, antibacterial, and antioxidant activity, supporting their applicability in integrated therapeutic strategies for skin-related conditions.

In this study, we combined experimental Piezoresponse Force Microscopy (PFM) analysis with an empirically corrected Furukawa model to predict the piezoelectric behavior of Poly(Vinylidene Fluoride-co-Trifluoroethylene) (PVDF-TrFE) films functionalized with CoFe₂O₄ (CFO) Magnetic Nanoparticles (MNPs). According to our empirical model, the piezoelectric response observed from PFM analysis on the PVDF-TrFE/CFO films was mainly influenced by the interaction between the CFO MNPs and the polymer active β phase of the polymer, providing a high piezoelectric coefficient d₃₃ (~ 6.5 pm/V) at a low CFO concentration of 5 wt%. Experimental observation of the morphological formation of the polar β domains and their phase dependence from the CFO MNPs amounts have been investigated by means of Scanning Electron Microscopy (SEM), Atomic Force Microscopy (AFM), and Fourier Transform Infrared (FT-IR) spectroscopy analysis. Also, the local magnetic response of the PVDF-TrFE/CFO film at 5 wt% was investigated through Magnetic Force Microscopy (MFM) with a controlled magnetized tip. DC magnetic poling of the PVDF-TrFE/CFO film at 5 wt% resulted in a significant increase in the d₃₃ (~ 34 pm/V) under an applied external magnetic field of ~ 50 mT. A theoretical model of chain aggregate-like structure formation in magnetizable polymer-based nanocomposites was employed to explain the effect of CFO MNP chain unification on the local piezoelectric strain response of PVDF-TrFE/CFO films under low magnetic fields. This finding provide further insight into the implementation of flexible PVDF-TrFE/CFO thin nanocomposites with tailored piezoelectric performance, enhancing their efficiency in energy harvesting and advancing the development of next-generation piezoelectric devices.

Intense ns laser pulses can be employed to generate carbon plasma by ablation of carbon vitreous targets in a high vacuum. The high plasma temperature (up to about 80 eV) and density (up to about 0.2 μg/cm³ in the first μs) and the high energy (up to about 2.5 keV C ions) of ablated ions produce carbon vapor, atom nucleation, and the growth of nanostructures. The carbon atoms in plasma may generate aggregates with high molecular weight, bonding energy, and stability, such as nanostructures with high density and ordered configurations. The technique of the laser ablation of carbon vitreous assisted by mass quadrupole spectrometry has permitted the ablation of the target glassy carbon surface and the analysis of the masses of the carbon-aggregated laser plasma generated in vacuum. It has been observed that a high yield is due to the C₂₀ fullerenes synthesis (240 amu), together with different precursors of carbon molecules, such as C₁₇–C₁₉ and C_21–23. The yield of C₂₀ generation is higher with respect to these precursors, indicating higher stability. The conditions to generate these carbon atom aggregates are presented as a function of the laser parameters (pulse energy from 100 mJ up to 500 mJ) and plasma characteristics. The dynamic of the C₂₀ formation is also reported, as well as the possible applications of these carbon-aggregated nanostructures.

This study reports a novel silver nanoparticle (AgNP)-enhanced ultraviolet–visible (UV–Vis) spectrophotometric assay for rapid and sensitive detection of Escherichia coli in milk samples. Conventional E. coli detection methods are time-consuming and require specialized equipment, limiting accessibility in many settings. The assay exploits the localized surface plasmon resonance (LSPR) of AgNPs, enabling detection within 20 min. AgNPs synthesized with trisodium citrate were characterized by atomic force microscopy (AFM) and UV–Vis spectrophotometry, showing a distinct LSPR peak at 421 nm. When mixed with E. coli suspensions, the peak shifted to 298 nm, lying between that of E. coli suspension alone (289 nm) and AgNPs alone (421 nm), indicating nanoparticle binding to bacterial surfaces. The assay demonstrated strong linearity for concentrations from 1.5 × 10³ to 1.5 × 10⁷ CFU/mL, with a detection limit of 3.47 × 10² CFU/mL, indicating good sensitivity. Specificity tests with Staphylococcus aureus verified accuracy. Application to milk samples showed quantitative overestimation relative to culture methods, attributable to matrix interference, though both methods achieved 100% agreement in qualitative detection. This rapid, sensitive, and specific assay is promising for use in resource-limited settings. With further optimization, it could serve as a valuable platform for bacterial contamination screening, enhancing food safety and public health surveillance.

Titanium dioxide nanoparticles (TiO₂ NPs) were effectively produced in carboxymethyl cellulose (CMC) using pulsed laser ablation. The nanoparticles were then analyzed for their antimicrobial properties. A pulsed Nd:YAG laser beam with certain parameters was directed onto a high-purity titanium metal plate submerged in a CMC solution to create colloidal titanium oxide nanoparticles. The TiO₂ NPs were analyzed using ultraviolet–visible (UV–Vis) spectroscopy, field emission scanning electron microscopy–energy-dispersive spectroscopy (FE-SEM–EDS), and Fourier transform infrared spectroscopy (FTIR) to determine surface morphology, nanoparticle size, crystal structure, and chemical bonding. The findings confirmed that the TiO₂ NPs exhibit a white hue. This nanoparticle has a spherical shape with average diameter of 45 nm. The TiO₂ nanoparticles consist of hydroxyl, carboxyl, covalent, and titanium–oxygen bonds, with the titanium–oxygen bond seen at 555 cm⁻¹ in the low wavenumber range. Testing Escherichia coli with increased doses of TiO₂ NPs resulted in a bigger inhibitory zone and a higher likelihood of diminishing bacterial colonies. TiO₂ nanoparticles were effectively produced as antibacterial agents.

There is a growing need for eco-friendly techniques to synthesize nanoparticles, with the plant-mediated green synthesis method emerging as an environmentally sustainable alternative to conventional chemical methods. Here, a leaf extract from Hybanthus enneaspermus, a medicinal plant rich in phytochemicals was used as the starting material to synthesize TiO₂ nanoparticles as well as their silver (Ag), gold (Au), and Ag–Au co-doped variants via green hydrothermal routes. This study marks a unique application of plant extract that enables simultaneous co-doping, yielding versatile nanoparticles with enhanced multifunctional properties from a single origination point. These nanoparticles were thoroughly evaluated using XRD, FTIR, SEM, UV–Vis, PL, and EDAX techniques. XRD analysis confirmed the anatase phase with crystallite sizes between 9 and 15 nm; SEM images revealed nanorod-like structures without significant metal doping agglomeration upon doping; EDAX confirmed successful incorporation of Ag and Au; UV–Vis analysis revealed redshift in absorption due to doping; while PL spectra showed decreased intensity which confirmed doping effects as indicating reduced electron–hole recombination as well as enhanced photocatalytic potential. Ag-doped TiO₂ nanoparticles demonstrated strong antibacterial activity against Staphylococcus aureus (zone of inhibition: 39 mm), while Ag–Au co-doped TiO₂ showed superior antioxidant activity with the lowest IC50 value for DPPH scavenging assays; these improvements can be attributed to synergistic interactions between metal dopants and bioactive compounds in plant extract. This study presents a cost-effective, sustainable, and non-toxic route for synthesizing doped TiO₂ nanoparticles with enhanced antioxidant and antibacterial properties for potential applications in biomedical and environmental technologies.

The eco-friendly and sustainable character of the green synthesis of nanoparticles using plant-based materials has attracted significant attention. This investigation investigates the biosynthesis of copper nanoparticles (CuNPs) through the use of methanol extracts from Eupatorium adenophorum, an invasive plant that is abundant in bioactive phytochemicals. The plant extract's reduction of copper ions was visually detected by a distinct color change and subsequently verified through ultraviolet–visible (UV–Vis) spectroscopy. Functional groups that are responsible for the stabilization and capping of CuNPs were identified through Fourier transform infrared spectroscopy. Compared to the plant extract alone, the synthesized nanoparticles exhibited significantly larger inhibition zones against Escherichia coli, Pseudomonas aeruginosa, Salmonella enterica, Staphylococcus aureus, and Micrococcus luteus, indicating potent antibacterial activity. These results underline the potential of E. adenophorum as a sustainable resource for nanoparticle synthesis, providing a dual benefit of repurposing an invasive species and contributing to green nanotechnology. This research points out the achievable applications of plant-mediated CuNPs in biomedical and environmental innovations.