Papers by Keyword: Metal Nanoparticles

Abstract: The paper presents new data on the complex use of colloidal solutions of nanoparticles (NPs) and low-intensity laser radiation on the biosynthetic activity of the edible medicinal mushroom Lentinula edodes (L. edodes) in vitro. Traditional mycological methods, colloidal solutions of metals (Ag, Fe, and Mg NPs), and unique photobiological methods were used. An argon laser at wavelength of 488 nm was used as a source of coherent visible light. It was found that colloidal solutions of NPs of all used metals increased (26–39%) the growth characteristics of L. edodes, while irradiation of the fungus inoculum with laser light in a medium with NPs reduced the growth activity of the L. edodes mycelium. The addition of all NPs to the nutrient medium with the inoculum inhibited the synthesis of extracellular polysaccharides, the greatest effect was observed with Fe NPs. At the same time, laser light irradiation in the presence of NPs increased the amount of extracellular polysaccharides; the greatest effect was observed in photoinduced Mg NPs, which stimulated the synthesis of extracellular polysaccharides by 47%. The introduction of NPs into the inoculum reduced the amount of intracellular polysaccharides in the mycelial mass; the greatest inhibitory effect of 50% was observed for Ag NPs. At for the photoinduced NPs, they stimulated the synthesis of intracellular polysaccharides in the mycelial mass of L. edodes. Treatment of the inoculum in a medium with NPs and photoinduced NPs caused an intensification of the synthesis of phenolic compounds in the mycelial mass and an increase in radical scavenging activity (RSA). The highest RSA values were recorded for samples obtained from inoculum treatment with photoinduced Fe and Mg NPs, respectively, for methanol and ethanol extracts of mycelial mass. The obtained results suggest the possibility of complex use of colloidal solutions of Fe, Ag, and Mg NPs and low-intensity laser radiation as environmentally friendly factors regulating biosynthetic activity in biotechnology of cultivating the valuable medicinal fungus L. edodes.

Abstract: The nervous system plays a vital role in maintaining overall health. Recent nanotechnology advances enable precise control of neuronal activity using metal nanoparticles, which convert external stimuli into electrical, mechanical, or thermal signals to modulate excitability. This review explores three primary neuromodulation strategies (e.g., electrical, magnetic, and optothermal stimulation) where magnetic methods create magnetothermal and magnetomechanical effects, optothermal techniques use surface plasmon resonance to activate heat-sensitive ion channels, and electrical approaches alter membrane potential via the high conductivity of nanoparticles. These methods hold significant potential for treating neurological disorders such as chronic pain, epilepsy, and Parkinson’s disease, though challenges like biocompatibility, metal ion toxicity, and efficient nanoparticle clearance must be addressed. To overcome these barriers, ongoing research focuses on coating nanoparticles with protective layers, modifying their surfaces to improve safety, and designing them in ways that help the body clear them more easily. Incorporating targeted delivery systems, biodegradable materials, and stimuli-responsive coatings into nanoparticle design could further improve safety, enhance personalization, and enable precise, reversible control of brain circuits, opening new avenues for treating neurological conditions.

Abstract: As a preliminary step to establish technology for fabricating High-Entropy Alloys (HEAs) that can make a large-scale HEA using a pulse laser with high peak intensity and high-repetition in the future, we fabricated alloys in which two types of metal atom are mixed close together in the order of nanometers. For the method to produce the alloy, metal alloy nanoparticles were prepared by irradiating the material in liquid with focused high-repetition Q-switched laser pulses using an in-liquid laser ablation method. When brass powder was used as an original material, analysis results by TEM showed that numerous nanoparticles mixed with copper and zinc atoms could be produced. Furthermore, it was clarified by SEM EDS that copper and zinc atoms in the nanoalloy were maintained at a ratio of 3:1 in sintered alloy, and that the atoms were spatially uniformly distributed over a wide range in sintered metal.

Abstract: Monodispersed Ag nanorods were synthesized using a one-pot synthesis method. These Ag nanorods normally manifest dual surface plasmon resonance (SPR) peaks. This work presents a study of the variation of SPR peaks with variation in the shape of Ag nanorods. Shape variation was achieved through the degradation of a shape-controlling agent (PVP in this work) under white light irradiance with silica passivation to halt further shape variations. This paper also reports the growth & characterization of thin films of the synthesized rod-shaped silver nanoparticles on glass slides along with studies on band pass filter characteristics of the as-synthesized nanoparticles.

Abstract: The paper presents the results of experimental studies of a photoactive catalyst in the form of barium titanate fibers with deposited particles of nickel, platinum and gold. Barium titanate fibers were synthesized by the molten salt method. The obtained barium titanate fibers were studied by SEM, TEM, XRD, and Raman spectroscopy. Photocatalytic studies showed that barium titanate fibers with platinum nanoparticles are the most active of the three prepared Metal/BaTiO3 samples.

Abstract: A simple method to synthesize metal nanoparticles (Nps) has been proposed using high vacuum thermal deposition (HVTD) by reverse engineering of thin films to Nps. Metal Nps synthesized by this technique corresponds to the top-down approach of nanomaterial synthesis from bulk metals of silver and copper wires to metal Nps. A high-vacuum thermal deposition is a commonly used technique for thin-film deposition in many applications. Synthesis of metal Nps by HVTD is simple, efficient, and can provide particle of about few tens of nanometers is effortless. A precoated thin layer of polyethylene glycol (PEG) on a glass substrate (Petri dish), is allowed deposit with a metallic thin film by thermionically evaporating bulk metal wires in high vacuum. The deposited metal thin film is removed along with the PEG coating into a liquid medium and subjected to sonication, stirring, and deoxidation. Obtaining the particle size in tens of nanometer range in one step is one projecting factor by HVTD technique. Also, providing the feasibility of reusing large particles as precursors after synthesis is a unique vantage point. The Nps were analyzed by various characterizations tools to evaluate the underlying properties.

Abstract: In this paper, the deposition and optical properties of charge-stabilized gold nanoparticles on silicon oxide substrates is studied, which have been derivatised with (aminopropyl) triemethoxysilane. Monodispersed charged-stabilized colloidal gold nanoparticles with diameters between 20-150 nm were prepared and their self-assembly and optical properties on silica substrates is studied. Atomic force microscopy (AFM) is employed to investigate the nanoparticle monolayers ex situ. Analysis of AFM images provide evidence that the formation of the colloidal nanoparticle monolayers is governed by random sequential adsorption. The results indicate that the ionic strength of the suspension influences the spatial distribution of the nanoparticles. For all sizes of the Au nanoparticles tested, optical simulations of extinction coefficients made by finite-difference time domain (FDTD) indicate a resonance peak in the range of 510-600 nm wavelength of the visible range of the electromagnetic spectrum. The results indicate a simple and inexpensive approach of assembly of plasmonic nanostructures that can find applications in metamaterials and light waveguides.

Abstract: This paper presents the results of experimental studies of arrays of Ag_0.52Au_0.48 alloy nanoparticles. Arrays were formed by vacuum-thermal evaporation on an unheated substrate and subsequent low-temperature vacuum annealing. The TEM images of the obtained nanoparticle arrays and corresponding histograms of particle size distribution are shown. The transmission spectra of these arrays showing the displacement of the plasma frequency as a function of the mean particle size are obtained. Spectra of Raman scattering from a thin film of amorphous carbon in presence of AgAu particles are obtained, and a comparative analysis of Raman scattering amplification factors for pure Ag, pure Au and Ag_0.52Au_0.48 alloy nanoparticles is presented.

Abstract: The various carbon nanostructures e.g. single-walled carbon nanotubes (SWCNTs) web, graphene nanosheets and metal nanoparticle decorated graphene sheets have been synthesized in large quantity by electrical arc discharge method under an argon atmosphere. The as-synthesized nanostructures were characterized by different characterization techniques such as XRD, SEM, TEM, Energy dispersive X-ray spectroscopy, Raman and FTIR spectroscopy. The SWCNT webs of length ~6 cm abundantly containing aligned SWCNTs have diameter of about 1.8 nm and form buckybook like structure. Few layer graphene (FLG) sheets were prepared by electric arc discharge of high purity graphite electrodes in a varying argon gas atmosphere (250-500T). The largest areal extent of graphene (with lowest number of layer i.e. four) has been found at 350T argon pressure. A one step method is also reported for the decoration of these graphene nanosheets with iron and nickel nanoparticles through arc discharge method.

Abstract: The field of application of electrochemical analysis has been significantly widened after modified electrodes appeared. Metallic nanoparticles are ones of the most common used modifiers of the electrode surface to increase the sensitivity and selectivity of the analysis. Increasing of selectivity is extremely important in cases when two or more analyts have electro-chemical signals at nearly the same values of electrode potential. Dopamine and ascorbic acid are an example of such case. In present work Au, Pt, Pd, and Ni “pure” nanoparticles obtained by laser ablation without stabilizing agents were used to modify the surface of a glassy carbon electrode. Modified electrodes were tested in solutions of ascorbic acid and dopamine at their simultaneous electro-oxidation. It was shown that Au, Pt, and Ni nanoparticles on the electrode surface increase the selectivity of analysis giving two separate peaks of analyts.