Silver Nano/Microparticles: Modification and Applications

Silver nanoparticle-based drug delivery systems in the fight against COVID-19: enhancing efficacy, reducing toxicity and improving drug bioavailability

Nanoparticles (NPs) have played a pivotal role in various biomedical applications, spanning from sensing to drug delivery, imaging and anti-viral therapy. The therapeutic utilisation of NPs in clinical trials was established in the early 1990s. Silver nanoparticles (AgNPs) possess anti-microbial, anti-cancer and anti-viral properties, which make them a possible anti-viral drug to combat the COVID-19 virus. Free radicals and reactive oxygen species are produced by AgNPs, which causes apoptosis induction and prevents viral contamination. The shape and size of AgNPs can influence their interactions and biological activities. Therefore, it is recommended that silver nanoparticles (AgNPs) be used as a valuable tool in the management of COVID-19 pandemic. These nanoparticles possess strong anti-microbial properties, allowing them to penetrate and destroy microbial cells. Additionally, the toxicity level of nanoparticles depends on the administered dose, and surface modifications are necessary to reduce toxicity, preventing direct interaction between metal surfaces and cells. By utilising silver nanoparticles, drugs can be targeted to specific areas in the body. For example, in the case of COVID-19, anti-viral drugs can be stimulated as nanoparticles in the lungs to accelerate disease recovery. Nanoparticle-based systems have the capability to transport drugs and treat specific body parts. This review offers an examination of silver nanoparticle-based drug delivery systems for combatting COVID-19, with the objective of boosting the bioavailability of existing medications, decreasing their toxicity and raising their efficiency.

Nanotechnology's Applications and Potential in Various Fields

Since ancient times, several sorts of nanoparticles have been employed in the quickly expanding field of nanotechnology. These features include size, shape, and chemical as well as physical properties. Because of their small size and huge surface area, carbon-based nanoparticles, including fullerenes, carbon nanotubes, graphene, graphene oxide, and carbon-based quantum dots, have attracted a lot of attention in a variety of sectors, including biomedical applications. Lipid bilayers form the spherical vesicles known as liposomes. Magnetic resonance imaging (MRI) contrast agents are iron oxide nanoparticles. These materials are perfect for drug and delivery of genes, bioimaging, and bone repair because of their remarkable mechanical, electrical, visual, and chemical properties. However, concerns about potential asbestos-related diseases have arisen due to their length-to-width aspect ratio. Ceramic nanoparticles, on the other hand, are a common material in daily life and play a crucial role in bone repair, multiscale hybridisation, and aerospace structures. These nanoparticles can enhance osseointegration and bone development by mimicking the nanocomposition and nanoscale characteristics of bone tissue and enhance osteoconductive and osteoinductive capacities. Ceramic nanoparticles, however, have the potential to generate oxidative stress, which can result in irritation of the reticuloendothelial system, cytotoxicity to the heart, liver, and lungs, as well as toxicity to the cells that are attached. Additionally, oxidative stress, cell damage, and genotoxicity might result from the generation of free radicals by ceramic nanoparticles. Metal nanoparticles exhibit linear optical properties similar to molecular systems but arise from a different physical process. Semiconductor nanocrystals (NCs) are made from various compounds, such as silicon and germanium. Polyandry nanoparticles are particles approximately 10 and 10000 nanometers (nm) in size that can contain active substances. They have applications in vaccine delivery, gene therapy, and polymer nanoparticles (nanomedicine) for therapeutic applications.

Influence of the Type of Binder Used in the Treatment of Cotton Fabric with Montmorillonite Particles on the Release of Negative Ions

Throughout history, mineral clays have had a multitude of applications. With recent developments in the textile industry, they have been used for their antimicrobial properties. As a promising phyllosilicate with a negative layer charge, montmorillonite (MMT) was used in this work to treat cotton fabric to evaluate its ability to generate negative air ions (NAIs). The MMT was dispersed with varying binder concentrations. Resins of different composition (polyurethane or acrylic) was applied to cotton fabric by padding, and the negative ion count was measured. Two types of MMT with different characteristics were tested. Electronic microscopy (SEM) was used to study the presence of MMT particles on the cotton fabric surface, and the colors of the samples were tested. It was observed that the composition of the binder used had a significant influence on the number of negative ions released by the treated sample.

Obtaining Ultrafine Dispersions of Silver Particles in Poly(vinyl Alcohol) Matrix Using Mechanical Alloying

Mechanical alloying was performed to obtain a composite material with a homogeneous dispersion of silver particles in a poly(vinyl alcohol) (PVA) matrix. Silver is a bactericidal material, and PVA is a widely used biocompatible polymer. Therefore, this mix can lead to a potentially functional biomaterial. This study focuses on the combination of both materials, processed by mechanical alloying, which has a promising application potential. The silver (Ag) used was ultrafine, measuring between 200 and 400 nanometers, produced from silver nitrate (AgNO3) redox. The Attritor high-energy, water-cooled ball mill was used to mill PVA for 4 h, at 600 rpm speed rotation and 38:1 power milling. Mechanical alloying was demonstrated to cause particle refinement in PVA with a timespan of 1 h. A slight additional particle decrease occurred for long-time milling. A milling time of 4 h was used to disperse the silver particles in the polymer matrix homogeneously. Hot pressing films were produced from the obtained dispersion powders. The microstructural features were studied using several material characterization techniques. Antimicrobial Susceptibility Tests (AST), conducted in an in-vitro assay, showed a hydrophilic character of the films and a protection against bacterial growth, making the process a promising path for the production of surface protective polymeric films.

Fabrication of Ag micro-particles based on stress-induced migration by using multilayered structure with artificial holes array

Silver micro/nanomaterials have attracted a great deal of attention due to their superior physicochemical properties. The atomic migration driven by electromigration or stress-induced migration has been demonstrated to be a promising method for the fabrication of metallic micro-/nanomaterials because of the advantage of simple processing. However, how to realize the controllable fabrication and mass production is still the critical technical problem for the method to be used in large-scale industrial applications. In this paper, the multilayered samples consisted of copper foil substrate, Ti adhesive layer, Ag film, and TiN passivation layer and with arrays of artificial holes on the passivation layer were applied to prepare arrays of Ag micro-particles. For the purpose of controllable fabrication, stress-induced migration experiments combined with finite element simulation were applied to analyze the influence of the passivation layer thickness and the heating temperature on the atom migration and Ag particles growing behavior. And the relationship between size of the fabricated Ag particles and the processing parameters of stress-induced migration experiments were also investigated. As a result, a proper structure size of the multilayered samples and heating temperature were recommended, which can be used for the Ag micro-particles controllable fabrication and mass production.

Colorimetric detection of Hg(II) by γ-aminobutyric acid-silver nanoparticles in water and the assessment of antibacterial activities

In this work, we report the synthesis of silver nanoparticles (AgNPs) via a wet-chemical reduction procedure using citrate (Cit) and γ-aminobutyric acid (GABA) as stabilizers. The formation of GABA-Cit@AgNPs was confirmed by UV-vis spectroscopy with a surface plasmon resonance band at 393 nm clearly confirming the formation of silver nanoparticles. AgNPs were characterized using UV-vis spectroscopy, attenuated total reflectance-fourier transform infrared spectroscopy (ATR-FTIR), transmission electron microscope (TEM), energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), dynamic light scattering (DLS), and zeta potential. The as-prepared AgNPs can be used for the detection of hazardous mercury ions (Hg²⁺) in water by colorimetric method with a limit of detection (LOD) and limit of quantitation (LOQ) of 2.37 μM and 3.99 μM, respectively. The linear working range for Hg²⁺ detection is 5-35 μM and the sensor probe was applied to investigate Hg²⁺ in real drinking water samples with satisfied results. Rapid response to Hg²⁺ is also observed when the nanoparticles are composited within hydrogels. Moreover, GABA-Cit@AgNPs shows antibacterial activity against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). The fast and sensitive response of the proposed Hg²⁺ sensor, together with its antibacterial activities, makes GABA-Cit@AgNPs potentially applicable for the development of cheap, portable, colorimetric sensors in fieldwork.

Silver Nano/Microparticles: Modification and Applications 2.0

Currently, nano/microparticles are widely used in various fields [...].