Applied Nanoscience最新文献

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.

The present research reports the strain-specific interactions between probiotics and nanocurcumin using two widely used probiotic strains, Bacillus clausii and Lactobacillus rhamnosus GG. Bacillus clausii was characterized as a Gram-positive bacterium with variable growth patterns but exposure to nanocurcumin inhibited its growth, suggesting an antimicrobial effect. In contrast, Lactobacillus rhamnosus GG demonstrated enhanced growth in the presence of nanocurcumin, indicating a potential beneficial relationship. Despite a decrease in survival in simulated gastric fluid, Lactobacillus rhamnosus GG’s resilience in acidic environments highlights the challenges probiotics face in the gastrointestinal tract. These contrasting effects of nanocurcumin on the two strains emphasize the importance of understanding strain-specific interactions. The findings suggest that nanocurcumin could be utilized to optimize probiotic treatments, especially for gastrointestinal health, and warrant further research into its mechanisms and clinical applications.

Escalating use of amorphous silica nanowires (a-SiO_x NWs) in potential applications demonstrates the demand of novel processing techniques at nanoscale. Due to the imperfect structure and porous morphology, a-SiO_x NWs can be metal-modified which allows for electrical conduction under visible light. Unfortunately, their brittle nature at room temperature and nanometric-size make it demanding to precisely process and change shape from an elongated fiber to a sharply pointed tip. Here energetic electron beam (e-beam) irradiation of a-SiO_x and a-SiO_x NWs with gold-nanoparticles (Au-NPs) (Au–SiO_x NWs) is performed to develop diverse shaped nanoscale tips by optimizing e-beam parameters. Sharp amorphous tips (6 and 11 nm), extremely sharp Au-tips (4 and 6 nm), and relatively thick (16 and 18 nm) amorphous tips with average lengths of 50, 30, and 20 nm are formed at the centers of a-SiO_x and Au–SiO_x NWs when a tightly focused e-beam with beam spot size (~ 42 nm) equal to the diameters of NWs is centered at their axes and edge positions respectively. Au-tips thickening (4 or 6 to 22 nm) with reduction (20–16 nm) in length is observed when a uniform e-beam with beam spot size ~ 200 nm is employed. In-situ electron microscopy evaluation demonstrates that during e-beam processing, evaporation, diffusion, plastic flow, and dewetting are driven by positive curvature and e-beam activation effect. The combination of beam spot size and position can be used to tailor atomically sharp tips for wide applications, such as interconnects, biochemical sensing, scanning near-field optical microscopes, blue light emitters, and manipulations.

The rising threat of antimicrobial resistance in animal health necessitates the development of effective and sustainable alternatives to conventional antibiotics. The present study was taken up to explore the synergistic antibacterial potential of composite silver nanoparticles synthesized using Aloe barbadensis miller and Cymbopogon citratus. Phytochemical analysis was performed using the aqueous extracts of the selected plants. Silver nanoparticles (AgNPs) were synthesized from the respective plant extracts and different composites ratios of synthesized nanoparticles were prepared and characterized by UV–Vis spectrophotometry, scanning electron microscopy (SEM), dynamic light scattering (DLS) and inverted microscopy. Minimum inhibitory concentration (MIC) and antimicrobial efficacy of the test compounds was evaluated against common field isolates of Staphylococcus aureus, Klebsiella pneumoniae and Escherichia coli. Phytochemical analysis revealed bioactive compounds saponins, tannins, phenols, flavonoids, proteins, glycosides and essential oils. Visible observation of color changes and UV–visible spectra exhibited plasmon peaks at 409 nm and 410 nm for individual plant AgNPs and composite at 418 nm. SEM showed spherical AgNPs with uniform distribution. DLS revealed average size of 50 nm. Inverted microscopy showed concentric ring structures. MIC showed appreciable inhibition and ABST using disk diffusion (Bauer-Kirby) revealed substantial zones of inhibition against above bacterial isolates. These findings suggest composite green nanoparticles could be a promising alternative for combating bacterial infections in animals upon confirming its efficacy on different clinical cases.

Utilizing an effective transformation method is fundamental in genetic and gene delivery studies. In this study, electrospray was evaluated as a simple, cost-effective and highly efficient approach for preparing monodispersed chitosan nanoparticles (CS NPs) carrying plasmid DNA (pDNA) and delivering them to bacteria. CS/pDNA NPs were prepared at three N/P ratios (molar ratio of chitosan nitrogens to DNA phosphates) of 3, 5, and 10. Size of nanoparticles was obtained as 323, 333, and 399 nm, respectively, using DLS. E. coli was made competent using CaCl₂ or CaCl₂–MgCl₂. Then, preformed CS/pDNA NPs, prepared using electrospray, were added to the heat-shocked bacteria. Alternatively, CS and pDNA solutions were mixed and directly electrosprayed on the bacteria. The results showed that direct electrospray of the particles provided more efficient transformation compared with transformation using heat shock (i.e. preformed NPs). Also, N/P ratios of 5 and 3 had maximum transformation efficiency when using heat shock (i.e. mean ± SD 1.23 ± 0.13 × 10⁷ CFU/µg on CaCl₂–MgCl₂-made competent bacteria) and direct electrospray (i.e. mean ± SD 8.79 (0.12) × 10⁹ CFU/µg on CaCl₂-made competent bacteria), respectively. Furthermore, the use of MgCl₂–CaCl₂ for making the bacteria competent proved more efficient than CaCl₂ alone in the transformation process. The findings highlight electrospray as a cost-effective alternative for bacterial transformation technology.

The use of green synthesis allowed for the creation of nanocomposite samples utilizing celery extract. PMMA was dissolved in acetone and then added to the synthesized SnO₂ at concentrations of 25%, 50%, 75%, and 100% µl. This was done after the SnO₂ was the result of the synthesis process. The names S1, S2, S3, and S4 have been assigned to these concentrations. Bio nanoparticles/polymer nanocomposite measurements employing X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), atomic force microscopy (AFM), transmission electron microscopy (TEM), ultraviolet–visible spectroscopy (UV–vis), and the Fourier transform infrared (FTIR) showed that the fourth concentration (S4) had the highest antibacterial activity, making it the most effective formulation. XRD reveals the tetragonal rutile phase structure in SnO₂ nanoparticles prepared by green synthesis method. The agglomeration effect and particle sizes cause this. TEM showed nanoparticles dispersed throughout the polymer with occasional agglomerations. Nanoscale dispersion was evident in the average particle size of 16.89 nm. FTIR study showed no chemical interaction because no new peaks formed and both SnO₂ and PMMA’s distinctive peaks remained constant. This implies that the compounds did not collide. The fact that the polymer was not dissolved in the SnO₂ is demonstrated by this fact, indicating that the mixing was entirely physical, as the SnO₂ peak at 610 cm⁻¹ shows no chemical changes in the material. The energy gap of this material can reach 3.85 eV, and its optical characteristics are better. Heat adaption allows the system to adjust to thermal imaging temperature variations. Higher thermal imaging temperatures reduce thermal stress and polymer expansion, indicating stability. Resistance to stretching and strain integrity indicate mechanical and thermal stability. Controlling thermal expansion in prosthetics prevents material deformation and ensures structural reliability. Tin dioxide (SnO₂) was tested on Staphylococcus aureus, Staphylococcus epidermidis, Escherichia coli, Pseudomonas aeruginosa, and Candida albicans active site residues using molecular docking. C. albicans had the lowest binding affinity (−6.1464 kcal/mol) and P. aeruginosa the highest. Due to hydrogen-ion interactions, the bond was maintained. Medical and thermal applications like biothermal imaging and prostheses could benefit from SnO₂-PMMA. This work fills a literature gap, proving its originality. Heat and mechanical stability without chemical reaction from celery extract with thermography for green PMMA polymer nanocomposites. Additionally, integrating in vitro testing and molecular docking to understand the microbial mechanism at the molecular level boosts the potential of these materials for medical applications, notably prostheses, which