The Recent Progress on Silver Nanoparticles: Synthesis and Electronic Applications

Spirothiazolidine-Derivative on Silver Nanoparticles and Carbon Nanotubes: Evaluation of Antibacterial, Anti-Fungal, Anti-Inflammatory, Antioxidant and Gastroprotective Activities

This study aims to develop innovative heterocyclic nanocomposites incorporating silver nanoparticles (SNPs) for potential therapeutic applications targeting infections, gastric ulceration, inflammation, and oxidative damage. By synthesizing new derivatives of spiro-thiazolidine-carbonitrile (Py-ST-X) and incorporating them into Ag nanoparticles (AgNPs) and carbon nanotubes (CNTs), we have prepared Ag@Py-ST-X and Ag@Py-ST-X@CNT nanocomposites, respectively. The physical properties of these materials were studied using XRD, TEM, SEM, and Zeta potential techniques. In our investigation involving rats with gastric ulcers, we observed noteworthy inhibitory effects on gastric acid enzyme activity, specifically H+/K+ATPase, by Ag@Py-ST-NO2 and Ag@Py-ST-Br nanocomposites, demonstrating reductions of 25 and 34%, respectively, compared to untreated ulcers. Nanotubulation of these compounds further improved their inhibitory efficacy to 29 and 45%, respectively. Additionally, these nanoparticles showed the most potent myeloperoxidase (MPO)-inhibitory activity, demonstrating 36 and 49% inhibition, respectively, with nanotubulated versions reaching 44 and 53%. Moreover, Ag@Py-ST-NO2@CNT and Ag@Py-ST-Br@CNT nanotubes showed significant antioxidant activity, reducing thiobarbituric acid reactive substances (TBARS) by 35 and 51%, and hydrogen peroxide (H2O2) levels by 49 and 71%, respectively. These therapeutic effects were confirmed by reductions in gastric surface area (GSA) by 44% and 52%, a decrease in ulcer index (UI) from 80% to 44 and 38%, and an increase in curative index (CI) from 19 to 55 and 62% following administration of Ag@Py-ST-NO2@CNT and Ag@Py-ST-Br@CNT, respectively. Histological studies support these findings, suggesting the potential of these nanocomposites as promising candidates for treating various disorders.

Bacteriogenic synthesis of morphologically diverse silver nanoparticles and their assessment for methyl orange dye removal and antimicrobial activity

Nanotechnology and nanoparticles have gained massive attention in the scientific community in recent years due to their valuable properties. Among various AgNPs synthesis methods, microbial approaches offer distinct advantages in terms of cost-effectiveness, biocompatibility, and eco-friendliness. In the present research work, investigators have synthesized three different types of silver nanoparticles (AgNPs), namely AgNPs-K, AgNPs-M, and AgNPs-E, by using Klebsiella pneumoniae (MBC34), Micrococcus luteus (MBC23), and Enterobacter aerogenes (MBX6), respectively. The morphological, chemical, and elemental features of the synthesized AgNPs were analyzed by using UV-Vis spectroscopy (UV-Vis), Fourier transform-infrared spectroscopy (FTIR), X-ray diffraction (XRD), field emission scanning electron microscope (FESEM) and energy-dispersive spectroscopy (EDX). UV-Vis absorbance peaks were obtained at 475, 428, and 503 nm for AgNPs-K, AgNPs-M, and AgNPs-E, respectively. The XRD analysis confirmed the crystalline nature of the synthesized AgNPs, having peaks at 26.2°, 32.1°, and 47.2°. At the same time, the FTIR showed bands at 599, 963, 1,693, 2,299, 2,891, and 3,780 cm-1 for all the types of AgNPs indicating the presence of bacterial biomolecules with the developed AgNPs. The size and morphology of the AgNPs varied from 10 nm to several microns and exhibited spherical to porous sheets-like structures. The percentage of Ag varied from 37.8% (wt.%) to 61.6%, i.e., highest in AgNPs-K and lowest in AgNPs-M. Furthermore, the synthesized AgNPs exhibited potential for environmental remediation, with AgNPs-M exhibiting the highest removal efficiency (19.24% at 120 min) for methyl orange dye in simulated wastewater. Further, all three types of AgNPs were evaluated for the removal of methyl orange dye from the simulated wastewater, where the highest dye removal percentage was 19.24% at 120 min by AgNPs-M. Antibacterial potential of the synthesized AgNPs assessment against both Gram-positive (GPB) Bacillus subtilis (MBC23), B. cereus (MBC24), and Gram-negative bacteria Enterococcus faecalis (MBP13) revealed promising results, with AgNPs-M, exhibiting the largest zone of inhibition (12 mm) against GPB B. megaterium. Such investigation exhibits the potential of the bacteria for the synthesis of AgNPs with diverse morphology and potential applications in environmental remediation and antibacterial therapy-based synthesis of AgNPs.

Lukianov D, Gayanova TE, Voronova EV, Shishilov ON, Stepakhin VD. The Synthesis and Analysis of the Cytotoxicity of Al2O3-Supported Silver Nanoparticles Prepared by the Plasma Chemical Process Initiated by Pulsed MW Radiation in the Al2O3-Ag Powder Mixtures

An original plasma chemical process initiated by microwave discharge in a mixture of metal and dielectric powders was applied to prepare specific materials, which consisted of microsized spherical particles of aluminum oxide covered with silver nanoparticles. The prepared materials are highly uniform in shape, size distribution, and composition. Their cytotoxicity was investigated using the human cell lines MCF7, HEK293T, A549, and VA-13 and the bacterial strains E. coli JW5503 (ΔtolC) and E. coli K12. Their cytotoxicity was found not to exceed the cytotoxicity of the starting materials. Thus, the prepared materials can be considered highly promising for catalysis and biotechnology applications.

Cytosine-Rich Oligonucleotide and Electrochemically Reduced Graphene Oxide Nanocomposite for Ultrasensitive Electrochemical Ag+ Sensing

Silver ions (Ag+) are crucial in various fields, but pose environmental and health risks at high concentrations. This study presents a straightforward approach for the ultra-trace detection of Ag+, utilizing a composite of a cytosine-rich oligonucleotide (CRO) and an electrochemically reduced graphene oxide (ERGO). Initially, ERGO was synthesized on a glassy carbon electrode (GCE) through the reduction of graphene oxide (GO) via cyclic voltammetry. A methylene blue-tagged CRO (MB-CRO) was then anchored to the ERGO surface through π-π interactions, resulting in the formation of an MB-CRO-modified ERGO electrode (MB-CRO/ERGO-GCE). The interaction with Ag+ ions induced the formation of silver-mediated C-Ag+-C coordination, prompting the MB-CRO to adopt a hairpin structure. This conformational change led to the desorption of the MB-CRO from the ERGO-GCE, causing a variation in the redox current of the methylene blue associated with the MB-CRO. Electrochemical assays revealed that the sensor exhibits extraordinary sensitivity to Ag+ ions, with a linear detection range from 1 femtomolar (fM) to 100 nanomolars (nM) and a detection limit of 0.83 fM. Moreover, the sensor demonstrated high selectivity for Ag+ ions and several other benefits, including stability, reproducibility, and straightforward fabrication and operational procedures. Additionally, real sample analyses were performed using the modified electrode to detect Ag+ in tap and pond water samples, yielding satisfactory recovery rates.

Optimization and modelling of magnesium oxide (MgO) photocatalytic degradation of binary dyes using response surface methodology

Textile industry dye effluent contains a mixture of different kinds of dyes. Many times, photocatalysis is targeted as a solution for the treatment of dye effluent from the textile industry. Many researches have been published related to the photocatalysis of single textile dyes but in the real-world scenario, effluent is a mixture of dyes. Magnesium oxide (MgO) is used as a photocatalyst to treat a mixture (binary solution) of Methylene blue (MB) and Methylene violet (MV) along with individual MB and MV dyes in this article. MgO shows remarkable photocatalytic activity at about 93 and 88% for MB and MV dye in binary solution within 135 min. Furthermore, to study the influence of process parameters, experiments are designed with the help of the central composite design (CCD), and Response surface methodology (RSM) is used to study the interactions between parameters. For this study, five parameters are selected i.e., Photocatalyst dosage, initial concentration of both dyes, time of exposure to the light source, and pH of the binary solution. The photocatalytic process is also optimized and finally optimization of process parameters is validated with an experiment. The result of the validation experiment is very close to the predicted photocatalytic activity.

Impacts of Differentially Shaped Silver Nanoparticles with Increasingly Complex Hydrophobic Thiol Surface Coatings in Small-Scale Laboratory Microcosms

We investigated the impacts of spherical and triangular-plate-shaped lipid-coated silver nanoparticles (AgNPs) designed to prevent surface oxidation and silver ion (Ag+) dissolution in a small-scale microcosm to examine the role of shape and surface functionalization on biological interactions. Exposures were conducted in microcosms consisting of algae, bacteria, crustaceans, and fish embryos. Each microcosm was exposed to one of five surface chemistries within each shape profile (at 0, 0.1, or 0.5 mg Ag/L) to investigate the role of shape and surface composition on organismal uptake and toxicity. The hybrid lipid-coated AgNPs did not result in any significant release of Ag+ and had the most significant toxicity to D. magna, the most sensitive species, although the bacterial population growth rate was reduced in all exposures. Despite AgNPs resulting in increasing algal growth over the experiment, we found no correlation between algal growth and the survival of D. magna, suggesting that the impacts of the AgNPs on bacterial survival influenced algal growth rates. No significant impacts on zebrafish embryos were noted in any exposure. Our results demonstrate that the size, shape, and surface chemistry of AgNPs can be engineered to achieve specific goals while mitigating nanoparticle risks.

Oxidative stress and potential effects of metal nanoparticles: A review of biocompatibility and toxicity concerns

Metal nanoparticles (M-NPs) have garnered significant attention due to their unique properties, driving diverse applications across packaging, biomedicine, electronics, and environmental remediation. However, the potential health risks associated with M-NPs must not be disregarded. M-NPs' ability to accumulate in organs and traverse the blood-brain barrier poses potential health threats to animals, humans, and the environment. The interaction between M-NPs and various cellular components, including DNA, multiple proteins, and mitochondria, triggers the production of reactive oxygen species (ROS), influencing several cellular activities. These interactions have been linked to various effects, such as protein alterations, the buildup of M-NPs in the Golgi apparatus, heightened lysosomal hydrolases, mitochondrial dysfunction, apoptosis, cell membrane impairment, cytoplasmic disruption, and fluctuations in ATP levels. Despite the evident advantages M-NPs offer in diverse applications, gaps in understanding their biocompatibility and toxicity necessitate further research. This review provides an updated assessment of M-NPs' pros and cons across different applications, emphasizing associated hazards and potential toxicity. To ensure the responsible and safe use of M-NPs, comprehensive research is conducted to fully grasp the potential impact of these nanoparticles on both human health and the environment. By delving into their intricate interactions with biological systems, we can navigate the delicate balance between harnessing the benefits of M-NPs and minimizing potential risks. Further exploration will pave the way for informed decision-making, leading to the conscientious development of these nanomaterials and safeguarding the well-being of society and the environment.

A practical green synthesis method of Ag NPs using rosy periwinkle plant leaves for solar panel coating

Coated silver nanoparticles (Ag NPs) are currently receiving interest because of their numerous uses in various fields of electronics, antimicrobials, manufacturing sectors, optical science, and pharmaceuticals. Among others, it gained significant attention in the power electronic system. The goal of the proposed study is to use a cost-effective coating material for solar panels; to accomplish this, silver nanoparticles were synthesized from the leaves of the Rosy Periwinkle plants. Green synthesis and characterization, such as Ultraviolet Visible Spectrometer (UV-Vis) analysis, Scanning Electron Microscopy (SEM), Energy Dispersive X-ray Spectroscopy (EDX), and Fourier Transform Infrared Spectroscopy (FTIR), were carried out after the silver nanoparticles have been collected prior coating. As a consequence, the effectiveness is determined based on the conductivity test, and the resulting Ag NPs are then applied to the c-si layer of the solar panel. Additionally, a modelling and experimental analysis are performed in this study to ascertain the suggested framework's ability to measure energy before and after coating panels with Ag NPs. Specifically, the Voltage Current (VI) and Power Voltage (PV) characteristics were validated in this study for analyzing the effectiveness and the obtained results revealed that the coating of green synthesized Ag NPs generated 2 % more power than the reference solar panel under the same conditions. Further, hardware testing and simulation were both used to confirm the outcomes and effectiveness of the suggested method. The open circuit voltage (Voc), short circuit current (Isc), maximum peak voltage (Vmp), maximum peak current (Imp), and efficiency are taken into account when assessing how well the suggested system performs at tracking. Moreover, the current density characteristics were evaluated with respect to various irradiation conditions for both the typical solar as well as Ag NPs coated panels. From the observation, it is noted that the efficiency level of coated panel was improved up to 19.20 %, 18 %, and 17.20 % for the irradiations of 200 W/m2, 500 W/m2, and 1000 W/m2 respectively.

Synthesis of Silver Nanoparticles from Silver Closo-Dodecaborate Film for Enhanced Hydrogen Evolution

The icosahedral closo dodecaborate cluster [B12 H12 ]2- is gaining increasing interest due to its unique properties including the ease of functionalization, 3D aromaticity, and formation of metal salts with high ion conductivity. In this work, simple and effective preparation of silver closo dodecaborte (Ag2 B12 H12 ) films is reported by an electrochemical route. The size of the Ag2 B12 H12 particles in the films can be tuned from nanometers to micrometers by varying the electrochemical parameters. Ag nanoclusters with controllable sizes are successfully generated via electrochemical reduction reactions or thermal anneal of the Ag2 B12 H12 films. When tested for hydrogen evolution reaction (HER) in an acidic solution, the as-prepared Ag nanoparticles deliver a current density of 10 mA cm-2 at 376 mV overpotential. This research sheds light on a new synthesis of [B12 H12 ]2- based thin films, the generation of metal nano-powders, and their application in HER or other applications.

Quantifying Nanoparticle Layer Topography: Theoretical Modeling and Atomic Force Microscopy Investigations

A comprehensive method consisting of theoretical modeling and experimental atomic force microscopy (AFM) measurements was developed for the quantitative analysis of nanoparticle layer topography. Analytical results were derived for particles of various shapes such as cylinders (rods), disks, ellipsoids, hemispheres (caps), etc. It was shown that for all particles, their root-mean-square (rms) parameter exhibited a maximum at the coverage about 0.5, whereas the skewness was a monotonically decreasing function of the coverage. This enabled a facile determination of the particle coverage in the layer, even if the shape and size were not known. The validity of the analytical results was confirmed by computer modeling and experimental data acquired by AFM measurements for polymer nanoparticle deposition on mica and silica. The topographical analysis developed in this work can be exploited for a quantitative characterization of self-assembled layers of nano- and bioparticles, e.g., carbon nanotubes, silica and noble metal particles, DNA fragments, proteins, vesicles, viruses, and bacteria at solid surfaces. The acquired results also enabled a proper calibration, in particular the determination of the measurement precision, of various electron and scanning probe microscopies, such as AFM.

Colloidal Silver Nanoparticles Obtained via Radiolysis: Synthesis Optimization and Antibacterial Properties

Silver nanoparticles (AgNPs) with broad-spectrum antimicrobial properties are gaining increasing interest in fighting multidrug-resistant bacteria. Herein, we describe the synthesis of AgNPs, stabilized by polyvinyl alcohol (PVA), with high purity and homogeneous sizes, using radiolysis. Solvated electrons and reducing radicals are induced from solvent radiolysis and no other chemical reducing agents are needed to reduce the metal ions. Another advantage of this method is that it leads to sterile colloidal suspensions, which can be directly used for medical applications. We systematically investigated the effect of the silver salt precursor on the optical properties, particle size, and morphology of the resulting colloidal AgNPs. With Ag₂SO₄ precursor, the AgNPs displayed a narrow size distribution (20 ± 2 nm). In contrast, AgNO₃ and AgClO₄ precursors lead to inhomogeneous AgNPs of various shapes. Moreover, the optimized AgNPs synthesized from Ag₂SO₄ were stable upon storage in water and phosphate-buffered saline (PBS) and were very effective in inhibiting the growth of Staphylococcus aureus (S. aureus) at a concentration of 0.6 μg·mL^-1 while completely eradicating it at a concentration of 5.6 μg·mL^-1. When compared with other AgNPs prepared by other strategies, the remarkable bactericidal ability against S. aureus of the AgNPs produced here opens up new perspectives for further applications in medicine, cosmetics, the food industry, or in elaborating antibacterial surfaces and other devices.

A Comparative Study of Cancer Cells Susceptibility to Silver Nanoparticles Produced by Electron Beam

Introduction: Silver nanoparticles (AgNPs) have a wide range of bioactivity, which is highly dependent on particle size, shape, stabilizer, and production method. Here, we present the results of studies of AgNPs cytotoxic properties obtained by irradiation treatment of silver nitrate solution and various stabilizers by accelerating electron beam in a liquid medium. Methods: The results of studies of morphological characteristics of silver nanoparticles were obtained by transmission electron microscopy, UV-vis spectroscopy, and dynamic light scattering measurements. MTT test, alamar blue test, flow cytometry, and fluorescence microscopy were used to study the anti-cancer properties. As biological objects for standard tests, adhesive and suspension cell cultures of normal and tumor origin, including prostate cancer, ovarian cancer, breast cancer, colon cancer, neuroblastoma, and leukemia, were studied. Results: The results showed that the silver nanoparticles obtained by irradiation with polyvinylpyrrolidone and collagen hydrolysate are stable in solutions. Samples with different stabilizers were characterized by a wide average size distribution from 2 to 50 nm and low zeta potential from −7.3 to +12.4 mV. All AgNPs formulations showed a dose-dependent cytotoxic effect on tumor cells. It has been established that the particles obtained with the combination of polyvinylpyrrolidone/collagen hydrolysate have a relatively more pronounced cytotoxic effect in comparison to samples stabilized with only collagen or only polyvinylpyrrolidone. The minimum inhibitory concentrations for nanoparticles were less than 1 μg/mL for various types of tumor cells. It was found that neuroblastoma (SH-SY5Y) is the most susceptible, and ovarian cancer (SKOV-3) is the most resistant to the action of silver nanoparticles. The activity of the AgNPs formulation prepared with a mixture of PVP and PH studied in this work was higher that activity of other AgNPs formulations reported in the literature by about 50 times. Conclusions: The results indicate that the AgNPs formulations synthesized with an electron beam and stabilized with polyvinylpyrrolidone and protein hydrolysate deserve deep study for their further use in selective cancer treatment without harming healthy cells in the patient organism.

Blending Approach Preparation of PVA-g-PMA Films with Embedded "Green" Synthesized Silver Nanoparticles for Acetone Optical Detection

The blending approach (also known as the ex-situ approach) was used for the deposition of thin composite films comprising poly(vinyl alcohol-graft-methyl acrylate) (PVA-g-PMA) and silver nanoparticles (AgNPs). Firstly, the copolymer aqueous dispersion was synthesized through the redox polymerization of methyl acrylate (MA) on poly(vinyl alcohol) (PVA) using ammonium cerium (IV) nitrate as the initiator. Then, AgNPs were synthesized through a "green" method using the water extract of lavender based on by-products of the essential oil industry, and then they were blended with the polymer. Dynamic light scattering (DLS) and transmission electron microscopy (TEM) were used to determine nanoparticle size, along with their stability over time in suspension, during the 30-day period. Thin films of the PVA-g-PMA copolymer, with different AgNP volume fractions varying between 0.008 and 0.260%, were deposited via the spin-coating method on Si substrates, and their optical properties were explored. UV-VIS-NIR spectroscopy and non-linear curve fitting were used for the determination of the refractive index, extinction coefficient, and thickness of the films, while photoluminescence measurements at room temperature were conducted for studying the emission of the films. The concentration dependence of film thickness was observed and showed that thickness increased linearly from 31 nm to 75 nm when the nanoparticles' weight content increased from 0.3 wt% to 2.3 wt%. The sensing properties toward acetone vapors were tested in a controlled atmosphere by measuring reflectance spectra before and during exposure to the analyte molecules in the same film spot; the swelling degree of films was calculated and compared to the corresponding undoped samples. It was shown that the concentration of AgNPs of 1.2 wt% in the films is optimal for the enhancement of the sensing response toward acetone. The influence of AgNPs on the films' properties was revealed and discussed.

Combining the Potent Reducing Properties of Pecan Nutshell with a Solvent-Free Mechanochemical Approach for Synthesizing High Ag0 Content-Silver Nanoparticles: An Eco-Friendly Route to an Efficient Multifunctional Photocatalytic, Antibacterial, and Antioxidant Material

A straightforward, low-cost, and scalable solid-state mechanochemical protocol for the synthesis of silver nanoparticles (AgNP) based on the use of the highly reducing agri-food by-product pecan nutshell (PNS) is reported herein. Under optimized conditions (180 min, 800 rpm, PNS/AgNO₃ ratio = 55/45 w/w), a complete reduction in silver ions was achieved, leading to a material containing ca. 36% w/w Ag⁰ (X-ray diffraction analysis). Dynamic light scattering and microscopic analysis showed a uniform size distribution (15-35 nm average diameter) of the spherical AgNP. The 2,2-Diphenyl-1-picrylhydrazyl (DPPH) assay revealed lower-although still absolutely high (EC₅₀ = 5.8 ± 0.5 mg/mL)-antioxidant properties for PNS for the further incorporation of AgNP, supporting the efficient reduction of Ag⁺ ions by PNS phenolic compounds. Photocatalytic experiments indicated that AgNP-PNS (0.4 mg/mL) was able to induce the >90% degradation of methylene blue after 120 min visible light irradiation, with good recycling stability. Finally, AgNP-PNS demonstrated high biocompatibility and significantly light-enhanced growth inhibition properties against Pseudomonas aeruginosa and Streptococcus mutans at concentrations as low as 250 μg/mL, also eliciting an antibiofilm effect at 1000 μg/mL. Overall, the adopted approach allowed to reuse a cheap and abundant agri-food by-product and required no toxic or noxious chemicals, making AgNP-PNS a sustainable and easy-to-access multifunctional material.

Environmentally benign silver bio-nanomaterials as potent antioxidant, antibacterial, and antidiabetic agents: Green synthesis using Salacia oblonga root extract

Introduction: The use of plant extracts in the green synthesis of metallic nanoparticles is one of the simplest, most practical, economical, and ecologically friendly methods for avoiding the use of toxic chemicals. Method: Silver nanoparticles (AgNPs) were synthesized, employing a high-efficiency, non- toxic, cost-effective, green, and simple technique that included the use of Salacia oblonga root extract (SOR) as a capping agent compared to synthetic nanoparticles. The use of S. oblonga can be seen in traditional medicines for treating diabetes, obesity, rheumatism, gonorrhea, asthma, and hyperglycemia. The objectives of the current study were to green synthesize S. oblonga root extract silver nanoparticles (SOR-AgNPs), characterize them, and study their antioxidant, antibacterial, and antidiabetic activities. Result: The shape of SOR-AgNPs was spherical, at less than 99.8 nm in size, and exhibited a crystalline peak at XRD. The green synthesized SOR-AgNPs showed significant antioxidant properties like DPPH (80.64 μg/mL), reducing power capacity (81.09 ± SEM μg/mL), nitric oxide (96.58 μg/mL), and hydroxyl (58.38 μg/mL) radical scavenging activities. The MIC of SOR-AgNPs was lower in gram-positive bacteria. The SOR-AgNPs have displayed efficient inhibitory activity against α-amylase, with an EC50 of 58.38 μg/mL. Analysis of capping protein around the SOR-AgNPs showed a molecular weight of 30 kDa. Discussion: These SOR-AgNPs could be used as antibacterial and antidiabetic drugs in the future as it is cheap, non-toxic, and environmentally friendly. Bio-fabricated AgNPs had a significant impact on bacterial strains and could be used as a starting point for future antibacterial drug development.

Silver Nanoparticles: Bactericidal and Mechanistic Approach against Drug Resistant Pathogens

This review highlights the different modes of synthesizing silver nanoparticles (AgNPs) from their elemental state to particle format and their mechanism of action against multidrug-resistant and biofilm-forming bacterial pathogens. Various studies have demonstrated that the AgNPs cause oxidative stress, protein dysfunction, membrane disruption, and DNA damage in bacteria, ultimately leading to bacterial death. AgNPs have also been found to alter the adhesion of bacterial cells to prevent biofilm formation. The benefits of using AgNPs in medicine are, to some extent, counter-weighted by their toxic effect on humans and the environment. In this review, we have compiled recent studies demonstrating the antibacterial activity of AgNPs, and we are discussing the known mechanisms of action of AgNPs against bacterial pathogens. Ongoing clinical trials involving AgNPs are briefly presented. A particular focus is placed on the mechanism of interaction of AgNPs with bacterial biofilms, which are a significant pathogenicity determinant. A brief overview of the use of AgNPs in other medical applications (e.g., diagnostics, promotion of wound healing) and the non-medical sectors is presented. Finally, current drawbacks and limitations of AgNPs use in medicine are discussed, and perspectives for the improved future use of functionalized AgNPs in medical applications are presented.

Printed Platinum Nanoparticle Thin-Film Structures for Use in Biology and Catalysis: Synthesis, Printing, and Application Demonstration

This work describes the formulation of a stable platinum nanoparticle-based ink for drop-on-demand inkjet printing and fabrication of metallic platinum thin films. A highly conductive functional nanoink was formulated based on dodecanethiol platinum nanoparticles (3-5 nm) dispersed in a toluene-terpineol mixture with a loading of 15 wt %, compatible with inkjet printing. The reduced sintering temperatures (200 °C) make them interesting for integration in devices using flexible substrates and substrates that cannot tolerate high-temperature exposures. A resistive platinum heater was successfully printed as a demonstrator for integration of the platinum ink. The platinum nanoink developed herein will be, therefore, attractive for a range of applications in biology, chemistry, and printed electronics.

Phytotoxicity and Antimicrobial Activity of Green Synthesized Silver Nanoparticles Using Nigella sativa Seeds on Wheat Seedlings

Recently, the green synthesis of nanomaterials has grown in popularity and has become one of the most used approaches. Plant extracts are safe for the environment and could be cost-effective for nanoparticle preparation. Silver nanoparticles (AgNPs) have been synthesized using aqueous extracts of Nigella sativa (N. sativa) seeds. The formation of AgNPs was confirmed by using an X-ray diffractometer, a UV-visible spectrometer, and a transmission electron microscope. The phytotoxicity and genotoxicity of different AgNP concentrations (12.5, 25, 50, 75, and 100 μg·L−1) were evaluated by wheat (Triticum aestivum L.) seed germination. The results showed that AgNPs did not significantly affect germination, while root and coleoptile lengths decreased considerably. On the contrary, the biomass of seedlings markedly increased in response to AgNP treatments. Moreover, genotoxicity was detected, especially at high concentrations of AgNPs. DNA, RNA, and total soluble proteins of wheat seedlings significantly decreased. In addition, antimicrobial activities of biosynthesized AgNPs were detected.

Green synthesis of multifunctional MgO@AgO/Ag2O nanocomposite for photocatalytic degradation of methylene blue and toluidine blue

Introduction: In this paper, MgO@AgO/Ag₂O nanoparticles were greenly synthesized, the current idea is to replace the harmful chemical technique with an ecofriendly synthesis of metal oxide nanoparticles (NPs) utilizing biogenic sources. Methods: The current investigation was conducted to create silver oxide NPs decorated by MgO NPs (namely, MgO@AgO/Ag₂O nanocom-posite) using the leaves extract of Purslane (Portulaca Oleracea) as the reducing and capping agent. The nanopowder was investigated by means of X-ray diffraction, scanning electron mi-croscope, BET surface area, Fourier transform infrared, and UV-vis spectrophotom-eter studies. XRD studies reveal the monophasic nature of these highly crystalline silver nano-particles. SEM studies the shape and morphology of the synthesis AgO/Ag₂O and MgO@AgO/Ag₂O NPs. The presence of magnesium and oxygen was further confirmed by EDS profile. Results and discussion: The surface area was found to be 9.1787 m²/g and 7.7166 m²/g, respectively. FTIR analysis showed the presence of specific functional groups. UV-vis spectrophotometer studies show the absorption band at 450 nm due to surface plasmon resonance. The results have also indicated the high performance of the greenly synthesized AgO/Ag₂O NPs and MgO@AgO/Ag₂O NPs for photocatalytic activity dye degradation (methylene blue and toluidine blue).

Biosynthesis of Silver Nanoparticles at Various pH values and their Applications in Capturing Irradiation Solar Energy

BACKGROUND

Metallic nanoparticles (NPs), in general, are able, due to the high surface area per unit volume, to absorb the maximum incoming light flux through the vicinity of plasmonic structures and then provide local heating. Thus, silver (Ag) NPs has been used to generate heat and increase the temperature of water from solar radiation energy. The optimal plasmonic heating generation can be obtained as soon as the wavelength of the light source is close to the plasmonic resonance wavelength of Ag NPs.

OBJECTIVE

Ag NPs have been fabricated through a straightforward, cheap, as well as environmentally friendly approach. In this study, Salix babylonica L., weeping willow leaf extract has been utilized as a reducing, capping, and stabilizing agent, without using any other toxic materials. The importance of this study lies in the generation of hot electrons, which can be obtained by collecting the solar spectrum near the infrared and infrared regions, which cannot be obtained by the conventional photocatalytic devices.

METHODS

Numerous characterization techniques such as; UV-Vis, FT-IR spectroscopy, X-ray diffraction (XRD), X-ray Photoelectron Spectroscopy (XPS), scanning electron microscopy (SEM), and energy dispersive X-ray (EDX) analysis were used to study the optical, chemical, structural, morphological, properties of the Ag NPs.

RESULTS

The impact of pH on the properties of Ag NPs and their performance to generate heat during solar irradiation have been investigated intensively. This study showed that the synthesized Ag NPs with pH value 12 is the optimum condition and can increase the temperature of water dramatically.

CONCLUSION

An evaluation of the current patents displays that the field of green synthesis Ag NPs utilizing plant extracts is a vital field and produces rather stable, safe and effective Ag NPs. The novelty of this patent is that Ag NPs can be synthesized from a one-pot reaction without using any exterior stabilizing and reducing agent, which is not conceivable by means of the existing processes. This study, also, is rare and distinctive, and it demonstrates that even a slight quantity of the Ag NPs is significantly raising the temperature of water effectively.

Synthetic Conditions, Physical Properties, and Antibacterial Activities of Silver Nanoparticles with Exopolysaccharides of a Medicinal Fungus

Natural polysaccharides are attractive and promising biomacromolecules for the green synthesis of silver nanoparticles (Ag NPs) with a broad spectrum of useful functions. This study aims to evaluate the synthetic conditions and physical properties of Ag NPs using three fractions of exopolysaccharide (EPS), namely EPS-1, EPS-2, and EPS-3, produced by a medicinal fungus known as Cs-HK1, with variations in their chemical composition and molecular weight. Each of the EPS fractions had a unique set of optimal synthetic conditions (reaction time course, temperature, and reagent concentration), resulting in a specific range of Ag NP size distributions. The Ag NPs synthesized with the EPS-1 fraction had the smallest particle size (~160 nm) and the most significant antibacterial activities against Escherichia coli (Gram-) and Staphylococcus aureus (Gram+), with a minimal inhibitory concentration (MIC) of 0.2 mg/mL on E. coli and 0.075 mg/mL on S. aureus. The results proved the success of the scheme of this green synthesis scheme with all three EPS fractions and the potential antibacterial application of EPS-coated Ag NPs.

Green Synthesis of Silver Oxide Nanoparticles for Photocatalytic Environmental Remediation and Biomedical Applications

Among the most notable nanotechnology applications is its employment in environmental remediation and biomedical applications. Nonetheless, there is a need for cleaner and sustainable methods in preparing nanomaterials that use cheaper, more environment-friendly precursors than the conventional synthesis process. The green chemistry approach for the preparation of nanoparticles is becoming more attractive as it uses non-toxic chemicals and reagents. It also offers cost-effective synthesis process as it uses readily available plant sources and microbe as redox mediators in converting metallic cations to metal or metal oxide nanoparticles. The extracts of these plants and microbe sources contain phytochemicals and metabolites in variable quantities, which serve as redox mediators and capping agents that stabilize the biosynthesized nanoparticles. The present article reviews the recent studies on the fabrication of silver oxide nanoparticles (Ag2O-NPs) via plant-mediated and microbe-mediated green synthesis, giving a concise discussion on the green preparation of Ag2O-NPs employing extracts of different plants and microbial sources. The performances of the biosynthesized Ag2O-NPs are also reviewed, highlighting their potential use in photocatalysis and biomedical applications.

Facile Green Synthesis of Silver Nanoparticles Using Aqueous Leaf Extract of Origanum majorana with Potential Bioactivity against Multidrug Resistant Bacterial Strains

The high prevalence of nosocomial bacterial resistance contributes to significant mortality and morbidity around the world; thus, finding novel antibacterial agents is of vital concern. Accordingly, the present study attempted to synthesize silver nanoparticles (AgNPs) using a green approach. Aqueous leaf extract of Origanum majorana was used to synthesize AgNPs and the antibacterial efficiency against multidrug resistant bacterial strains was detected. Characterization of the biogenic AgNPs was performed using ultraviolet-visible spectrophotometry (UV-Vis), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDX), Fourier transform infrared spectroscopy (FT-IR) analysis, and X-ray diffraction analysis (XRD). The disc diffusion method was used to detect the antibacterial activity of AgNPs against three nosocomial multidrug-resistant strains. Preliminary UV-Vis analysis revealed the biosynthesis of AgNPs due to peak formation at 374 nm, corresponding to the surface plasmon resonance (SPR) of biogenic AgNPs. TEM micrographs detected the synthesis of small AgNPs with an average particle size of 26.63 nm. EDX analysis revealed the presence of the following elements: oxygen (3.69%), carbon (2.93%), aluminum (1.29), silicon (2.83%), chloride (17.89%), and silver (71.37%). Furthermore, XRD analysis revealed the presence of diffraction peaks at 2 theta (θ) degrees of 38.18°, 44.36°, 64.35°, and 77.54°, assigned to the planes of silver crystals (111), (200), (220), and (311), respectively. Collectively, these findings affirm the synthesis of biogenic AgNPs with potential physicochemical characteristics. The antimicrobial efficiency of the biogenic AgNPs indicated that Klebsiella pneumoniae strain was the most susceptible strain at concentrations of 50 and 100 µg/disk, with inhibitory zones of 21.57 and 24.56 mm, respectively. The minimum inhibitory concentration (MIC) of AgNPs against Klebsiella pneumoniae strain was found to be 10 µg/mL, while the minimum bactericidal concentration (MBC) was found to be 20 µg/mL. In conclusion, aqueous leaf extract of O. majorana mediated synthesis of small sized AgNPs, with potential antimicrobial effectiveness against multidrug-resistant bacterial pathogens.

Toxicity and Uptake of CuO Nanoparticles: Evaluation of an Emerging Nanofertilizer on Wheat (Triticum aestivum L.) Plant

Wet chemistry was used to produce copper oxide nanoparticles (CuO NPs). The results indicated that most nanoparticles were bacillus-shaped and relatively uniform in size (less than 30 nm). The effect of synthesized CuO NPs on wheat (Triticum aestivum L.) germination and growth parameters was studied and compared to bulk Cu. The results showed that no significant difference was obtained in germination rate among all treatments. Bulk Cu additions significantly affect the mean germination rate and mean germination time. On the contrary, germinability was significantly affected by CuO NPs additions. Seed vigor index was calculated to demonstrate the superior treatment in wheat germination parameters, and the results confirmed that 0.1 mg L−1 of CuO NPs could be successfully used to improve wheat seed germination. Moreover, the general average Cu concentrations in the plant tissue were 139 and 103 mg kg−1 dry weight for bulk and CuO NPs, respectively, indicating the dissolution behavior of CuO NPs. The addition of CuO NPs (0.1 mg L−1) promotes chlorophyll formation equal to 0.5 mg L−1 of the bulk Cu addition. This means using nanoparticles as fertilizer could reduce 80% of traditional fertilizers. Nonetheless, Cu additions in both forms (NPs and bulk) reduce root growth substantially compared to control. The effective toxic dose (EC50) for bulk Cu and CuO NPs was 0.37 mg L−1 and 0.94 mg L−1, respectively. The results indicated that approximately 2.5 times CuO NPs concentration is equal to the toxicity dose of bulk Cu due to lowered CuO NPs dissolution. Our study showed that Cu phytotoxicity is a non-nanosized effect and showed that plant-induced changes under environmentally real conditions should be considered when measuring the dissolution of CuO NPs near wheat plant roots. This study implies that using nano-CuO as a micronutrient amendment has a potential benefit rather than the soluble Cu salt for plant growth.

Nanoparticle and bioparticle deposition kinetics

Mechanisms and kinetic of particle deposition at solid surfaces leading to the formation of self-assembled layers of controlled structure and density were reviewed. In the first part theoretical aspects were briefly discussed, comprising limiting analytical solutions for the linear transport under flow and diffusion. Methods of the deposition kinetics analysis for non-linear regimes affected by surface blocking were also considered. Characteristic monolayer formation times under diffusion and flow for the nanoparticle size range were calculated. In the second part illustrative experimental results obtained for micro- and nanoparticles were discussed. Deposition at planar substrates was analyzed with emphasis focused on the stability of layers and the release kinetics of silver particles. Applicability of the quartz microbalance measurements (QCM) for quantitative studies of nanoparticle deposition kinetic was also discussed. Except for noble metal and polymer particles, representative results for virus deposition at abiotic surfaces were analyzed. Final part of the review was devoted to nanoparticle corona formation at polymer carrier particles investigated by combination of the concentration depletion, AFM, SEM and the in situ electrokinetic method. It is argued that the results obtained for colloid particles can be used as reliable reference systems for interpretation of protein and other bioparticle deposition, confirming the thesis that simple is universal.

Antibacterial Effect of Silver Nanoparticles Is Stronger If the Production Host and the Targeted Pathogen Are Closely Related

Microbial resistance to antibiotics is one of the key challenges that lead to the search for alternate antimicrobial treatment approaches. Silver nanoparticles (AgNPs) are well known for their antimicrobial effects against a wide variety of drug-resistant microorganisms. AgNPs can be synthesized using microbial hosts, using a green and economical synthesis route, which produces extremely stable and highly active nanoparticles. Such green AgNPs are coated with a biological coating often referred to as a corona, originating from the production microorganism. In this study, we asked whether the composition of the biological corona might influence the antimicrobial activity of green AgNPs. To investigate this, we produced AgNPs in Pseudomonas putida KT2440 and Escherichia coli K12 MG1655, and tested them against pathogen species from the corresponding genera. AgNPs exhibited a size range of 15–40 nm for P. putida and 30–70 nm for E. coli, and both types of nanoparticles were surrounded by a thick biological corona layer, providing extreme stability. The nanoparticles remained stable over long periods and exhibited negative zeta potential values. P-AgNPs (obtained from P. putida) were tested against pathogenic Pseudomonas aeruginosa PAO1, and E-AgNPs (obtained from E. coli) were tested against pathogenic Escherichia coli UTI 89. Antimicrobial studies were conducted by Minimum bactericidal concentration (MBC), live/dead staining and SEM analysis. MBC of P-AgNPs against P. aeruginosa was 1 μg/mL, and MBC of E-AgNPs against E. coli UTI 89 was 8 μg/mL. In both cases, the MBC values were superior to those of green AgNPs produced in organisms unrelated to the target pathogens, available in the literature. Our results suggest that NPs produced in microorganisms closely related to the target pathogen may be more effective, indicating that the composition of the biological corona may play a crucial role in the antimicrobial mechanism of AgNPs.

Grape Pomace Extracted Tannin for Green Synthesis of Silver Nanoparticles: Assessment of Their Antidiabetic, Antioxidant Potential and Antimicrobial Activity

In nanoscience, the "green" synthesis approach has received great interest as an eco-friendly and sustainable method for the fabrication of a wide array of nanoparticles. The present study accounts for an expeditious technique for the synthesis of silver nanoparticles (AgNPs) utilizing fruit waste grape pomace extracted tannin. Grape pomace tannin (Ta) involved in the reduction and capping of AgNPs and leads to the formation of stable Ta-AgNPs. Various conditions were attempted to optimize the particle size and morphology of Ta-AgNPs which was further analyzed using various analytical tools for different characteristic motives. UV-visible spectroscopy showed a characteristic peak at 420 nm, indicating successful synthesis of AgNPs. Energy disperses spectroscopy (EDS) analysis proved the purity of the produced Ta-AgNPs and manifested a strong signal at -2.98 keV, while Fourier-transform infrared spectrophotometer (FTIR) spectra of the Ta-AgNPs displayed the existence of functional groups of tannin. Zeta potential measurements (-28.48 mV) showed that the Ta-AgNPs have reasonably good stability. High resolution transmission electron microscopy (HR-TEM) analysis confirmed the average dimension of the synthesized NPs was estimated about 15-20 nm. Ta-AgNPs potentials were confirmed by in vitro antidiabetic activity to constrain carbohydrate digesting enzymes, mainly α-amylase and α-glucosidase, with a definite concentration of sample displaying 50% inhibition (IC50), which is about 43.94 and 48.5 μg/mL, respectively. Synthesized Ta-AgNPs exhibited significant antioxidant potential with respect to its 2,2'-azino-bis(3-ethylbenzothi-azoline-6-sulfonic acid) (ABTS) (IC50 of 40.98 µg/mL) and 2,2-diphenyl-1-picrylhydrazyl (DPPH) (IC50 of 53.98 µg/mL) free radical scavenging activities. Ta-AgNPs exhibited extraordinary antibacterial activity against selected pathogenic strains and showed comparable antimicrobial index against ampicillin as a positive control.

Facile Synthesis, Characterization, Photocatalytic Activity, and Cytotoxicity of Ag-Doped MgO Nanoparticles

Due to unique physicochemical properties, magnesium oxide nanoparticles (MgO NPs) have shown great potential for various applications, including biomedical and environmental remediation. Moreover, the physiochemical properties of MgO NPs can be tailored by metal ion doping that can be utilized in photocatalytic performance and in the biomedical field. There is limited study on the photocatalytic activity and biocompatibility of silver (Ag)-doped MgO NPs. This study was planned for facile synthesis, characterization, and photocatalytic activity of pure and silver (Ag)-doped MgO NPs. In addition, cytotoxicity of pure and Ag-doped MgO NPs was assessed in human normal umbilical vein endothelial cells (HUVECs). Pure MgO NPs and Ag-doped (1, 2, 5, and 7.5 mol%) MgO NPs were prepared via a simple sol-gel procedure. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared (FTIR), photoluminescence (PL), and X-ray photoelectron spectroscopy (XPS) were used to characterize the prepared samples. XRD results showed the preparation of highly crystalline NPs with no impurity peaks. TEM and SEM studies indicate smooth surfaces with almost spherical morphology of MgO NPs, and Ag-doping did not change the morphology. Elemental composition study suggested that Ag is uniformly distributed in MgO particles. Intensity of the PL spectra of MgO NPs decreased with increasing the concentration of Ag dopants. In comparison to pure MgO NPs, Ag-MgO NPs showed higher degradation of methylene blue (MB) dye under UV irradiation. The improved photocatalytic activity of Ag-MgO NPs was related to the effect of dopant concentration on reducing the recombination between electrons and holes. Cytotoxicity studies showed good biocompatibility of pure and Ag-doped MgO NPs with human normal umbilical vein endothelial cells (HUVECs). These results highlighted the potential of Ag-doped MgO NPs in environmental remediation.