Dispersion Of AgNPs Research Articles

Highly dispersed nanocomposite based on magnesium ion modified and silver nanoparticles loaded graphene oxide for enhanced antibacterial activity of silicone coatings

Silver nanoparticles (Ag NPs) possess excellent antibacterial properties and have received widespread attention. However, the poor dispersion and easy aggregation of Ag NPs can severely diminish their antibacterial efficacy, limiting their practical applications. In this work, we report a simple method for preparing graphene oxide (GO) nanocomposites (Mg-GO/Ag NPs), in which GO is modified by Mg2+ and uniformly loaded with Ag NPs. The Ag NPs have an average diameter of approximately 11.14 nm, and uniformly are deposited on the surface of the GO. Compared with GO, the dispersion of Mg-GO/Ag NPs in deionized water (DW) and N, N-dimethylformamide (DMF) is significantly improved. The reaction principle of preparing Mg-GO/Ag NPs was revealed by gas chromatography–mass spectrometry (GC–MS). Additionally, we studied the antibacterial properties of Mg-GO/Ag NPs coatings against marine bacteria and Navicula tenera. This study introduces a novel approach for the preparation of high-efficiency silver-based antifouling coatings, with promising potential for a wide range of marine antifouling applications.

Speciation-specific chromium bioaccumulation and detoxification in fish using hydrogel microencapsulated biogenic nanosilver and zeolite synergizing with biomarkers.

Grass carp intestinal waste-mediated biosynthesized nanosilver (AgNPs) was valorized using guaran and zeolite matrices, resulting in AgNPs-guaran, AgNPs-zeolite, and AgNPs-guaran -zeolite composites. The valorized products were examined using Environmental Scanning Electron Microscopy, Energy Dispersive X-ray analysis and X-ray Diffraction analysis to confirm uniform dispersion and entrapment of AgNPs within the matrixes. These valorized products were evaluated for their efficacy in detoxifying the ubiquitous and toxic hexavalent chromium (Cr6+) in aquatic environments, with Anabas testudineusexposed to 2mgl-1 of Cr6+ for 60days. Remarkable reduction of Cr6+ concentration to 0.86 ± 0.007mgl-1 was achieved with AgNPs-guaran-zeolite composite, indicating successful reclamation of contaminated water and food safety assurance. Consistency in results was further corroborated by minimal stress-related alterations in fish physiological parameters and integrated biomarker response within the experimental group treated with the AgNPs-guaran-zeolite composite. Despite observed chromium accumulation in fish tissues, evidence of physiological stability was apparent, potentially attributable to trivalent chromium accumulation, serving as an essential nutrient for the fish. Additionally, the challenge study involvingAnabas testudineus exposed to Aeromonas hydrophila exhibited the lowest cumulative mortality (11.11%) and highest survival rate (87.5%) within the same experimental group. The current study presents a novel approach encompassing the valorization of AgNPs for Cr6+ detoxification under neutral to alkaline pH conditions, offering a comprehensive framework for environmental remediation.

Green construction of self-floating polysaccharide-based hydrogels with catalytic activity for efficient organic pollutants reduction

This study employed an anionic heteropolysaccharide extracted from overgrown Enteromorpha and homopolysaccharide pullulan to fabricate a self-floating hydrogel by introducing bubble templates. Subsequently, green in-situ reduction and immobilization of silver nanoparticles (Ag NPs) in the hydrogel were successfully achieved without additional reducing agents. The heteropolysaccharide from Enteromorpha provides carboxyl and sulfate groups for Ag+ ions complexation, which is beneficial for the in-situ reduction of Ag NPs and inhibits their aggregation. The incorporation of bubble templates facilitates the creation of a hierarchical pore structure in the hydrogel, giving it self-floating properties for easy recycling, while the hierarchical network with rich anchor sites ensuring adequate traction for Ag NPs dispersion and stabilization. By adjusting polysaccharide content and using bubble templates, Ag NPs smaller than 10 nm can be obtained. The composite hydrogel exhibits tunable catalytic activity and excellent degradation towards Rhodamine B, Methyl Orange, and 4-Nitrophenol, with the normalized rate constant (knor) of 78.89, 59.08, and 30.42 min−1 g−1, respectively. Notably, the reduction efficiency remained above 98 % after 6 recycles with little leaching of Ag NPs, benefiting from its self-floating ability for easy recovery in practical applications.

Gamma Radiation-Mediated Synthesis of Antimicrobial Polyurethane Foam/Silver Nanoparticles.

Nosocomial infections represent a major threat within healthcare systems worldwide, underscoring the critical need for materials with antimicrobial properties. This study presents the development of polyurethane foam embedded with silver nanoparticles (PUF/AgNPs) using a rapid, eco-friendly, in situ radiochemical synthesis method. The nanocomposites were characterized by UV-vis and FTIR spectroscopy, scanning electron microscopy coupled with energy dispersive X-ray technique (SEM/EDX), differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), tensile and compression strengths, antimicrobial activity, and foam toxicity tests. The resulting PUF/AgNPs demonstrated prolonged stability (over 12 months) and good dispersion of AgNPs. Also, the samples presented higher levels of hardness compared to samples without AgNPs (deformation of 1682 µm for V1 vs. 4307 µm for V0, under a 5 N force), tensile and compression strength of 1.80 MPa and 0.34 Mpa, respectively. Importantly, they exhibited potent antimicrobial activity against a broad range of bacteria (including Pseudomonas aeruginosa, Staphylococcus aureus, Escherichia coli, and Enterococcus faecalis) and a fungal mixture (no fungal growth on the sample surface was observed after 28 days of exposure). Furthermore, these materials were non-toxic to human keratinocytes, which kept their specific morphology after 24 h of incubation, highlighting their potential for safe use in biomedical applications. We envision promising applications for PUF/AgNPs in hospital bed mattresses and antimicrobial mats, offering a practical strategy to reduce nosocomial infections and enhance patient safety within healthcare facilities.

Endogenous H2S-activated Ag nanoparticles embedded in programmed DNA-cubes for specific visualization of colorectal cancer cells.

To avoid the unexpected aggregation and reduce the cytotoxicity of nanomaterials as optical probes in cell imaging applications, we propose a programmed DNA-cube as a carrier for silver nanoparticles (Ag NPs) to construct a specific hydrogen sulfide (H2S) responsive platform (Ag NP@DNA-cube) for diagnosing colorectal cancer (CRC) in this study. The DNA-cube maintains good dispersion of Ag NPs while providing excellent biocompatibility. Based on the characteristic overexpression of endogenous H2S in CRC cells, the Ag NPs are etched by H2S within target cells into silver sulfide quantum dots, thereby selectively illuminating the target cells. The Ag NP@DNA-cube exhibits a specific fluorescence response to CRC cells and achieves satisfactory imaging.

Gellan gum-dopamine mediated in situ synthesis of silver nanoparticles and development of nano/micro-composite injectable hydrogel with antimicrobial activity

Infected skin wounds represent a serious health threat due to the long healing process and the risk of colonization by multi-drug-resistant bacteria. Silver nanoparticles (AgNPs) have shown broad-spectrum antimicrobial activity. This study introduces a novel approach to address the challenge of infected skin wounds by employing gellan gum-dopamine (GG-DA) as a dual-functional agent, serving both as a reducing and capping agent, for the in situ green synthesis of silver nanoparticles. Unlike previous methods, this work utilizes a spray-drying technique to convert the dispersion of GG-DA and AgNPs into microparticles, resulting in nano-into-micro systems (AgNPs@MPs). The microparticles, with an average size of approximately 3 μm, embed AgNPs with a 13 nm average diameter. Furthermore, the study explores the antibacterial efficacy of these AgNPs@MPs directly and in combination with other materials against gram-positive and gram-negative bacteria. The versatility of the antimicrobial material is showcased by incorporating the microparticles into injectable hydrogels. These hydrogels, based on oxidized Xanthan Gum (XGox) and a hyperbranched synthetic polymer (HB10K-G5-alanine), are designed with injectability and self-healing properties through Shiff base formation. The resulting nano-into-micro-into-macro hybrid hydrogel emerges as a promising biomedical solution, highlighting the multifaceted potential of this innovative approach in wound care and infection management.

Evaluation of antimicrobial, anti-inflammatory and cytotoxic effects of silver nanoparticles synthesised from Cynodon dactylon

Plant mediated synthesis of metal nanoparticles (MNPs) has been considered as a reliable green technique for mitigating the involvement of toxic chemicals and which is widely used for desired applications. In the present study, a simple and environment friendly approach for the synthesis of silver nanoparticles (AgNPs) using the aqueous extract of Cynodon dactylon was proposed. The phytochemicals present in C. dactylon acted as the reducing as well as the capping agents during the nanoparticle synthesis. The aqueous extract of C. dactylon added to AgNO3 solution showed a colour change from brown to black at room temperature which confirmed the formation of AgNPs. UV-Vis spectral analysis revealed the surface plasmon resonance band of synthesised AgNPs at around 380 nm, while FT-IR spectroscopy confirmed the role of biomolecules present in the plant extract in the reduction and efficient stabilisation of AgNPs. The X-ray diffraction (XRD) patterns confirmed distinctive peaks corresponding to the crystalline planes of cubic silver. Shape and surface morphology of green AgNPs were examined by SEM. Biosynthesized AgNPs were predominantly cubical and spherical with an average particle size of 30.5 nm approximately as observed through SEM and DLS analysis respectively. The EDS analysis displayed intense signals of silver element. The stability of AgNPs was confirmed by zeta potential analysis. A negative zeta potential value of −17.1 mV indicated the stability and good dispersion of AgNPs. Antimicrobial and anti-inflammatory potentials of green synthesised AgNPs were analysed through in vitro techniques. The cytotoxic effect of green AgNPs on normal fibroblast cells (L929) was studied to analyse its effect on normal cells.

Green Synthesis of Silver Nanoparticles: Their Optical and Rheological Properties

The goal of this work was to investigate the green synthesis of silver nanoparticles (Ag NPs) from aqueous Propolis (P) extract, and their optical and rheological properties. Using scanning electron microscopy (SEM), Energy Dispersive X-Ray Spectroscopy (EDS) and X-ray diffraction (XRD) studies nanostructure of the prepared Ag NPs were characterized. Further, the aforementioned study suggests that Ag NPs with an average size of around 23 nm have a well-developed polycrystalline cubic structure. In the UV-Vis absorption spectra, the surface plasmon resonance (SPR) peak showed maximum absorption at 418 nm. For an excitation energy corresponding to the wavelength 410 nm, photoluminescence (PL) spectra of Ag NPs exhibited emission peak at 495 nm. To explore temperature (T) dependent flow behaviour of biosynthesized colloidal Ag NPs dispersion in deionized (DI) water, flow curve studies under shear for T= 20, 30 and 40 °C were done using rheometer. The above study illustrated that the colloidal Ag NPs follows shear thickening non-Newtonian behaviour. Moreover, viscosity decreased as temperature increased, indicating that the silver nanofluids can exhibit more rational thermal performance under high temperature conditions.

Silica supported biosynthesized silver nanoparticles as effective adsorbent and photocatalyst for removal of methylene blue from water

The silica supported silver nanoparticles (Ag@SG) were prepared by wet impregnation of silica gel (SG) using different concentrations of biogenic silver nanoparticles (AgNPs; 0.25–5 mM) solution, prepared from Cicer arientinum pod extract. Among them, the Ag@SG composite prepared by using 1.25 mM AgNPs solution (Ag1.25@SG) was found to contain only Ag0 species as nanoparticles, whereas the samples prepared by higher concentrations contained Ag0 as well as Ag+ (silver oxide) species. All the Ag@SG composites including SG, exhibited good adsorption capacity for a cationic dye (methylene blue; MB) in water. However, Ag1.25@SG having only Ag0 species exhibited higher photocatalytic activity for degradation of MB under visible light irradiation as compared to other composites. The study reveals that the plasmonic Ag0 species supported on silica are catalytically more active than Ag+ species. Furthermore, the AgNPs (Ag0) in supported form exhibits much higher (∼5-fold) photocatalytic activity than unsupported AgNPs. The synergistic effect of adsorption property of silica surface and plasmonic photocatalytic activity of AgNPs in the synthesized composites was found to be effective for the removal of MB. In addition, the fine dispersion of AgNPs on internal surface of silica provides better activity for photocatalysis. The study shows that this material is a promising adsorbent as well as photocatalyst for the removal of dyes from water.

Efficient self-cleaning and antibacterial ceramics with ultra-low doping and high exposure of silver

The secondary bacterial infection of COVID-19 is known to contribute significantly to mortality rates. Silver (Ag)-based antibacterial ceramics have emerged as a prominent solution for daily antibacterial applications, aiming to minimize the reliance on disinfectants while safeguarding human health. However, the fabrication of Ag-based antibacterial ceramics with low Ag content, high dispersion, and high exposure still faces challenges. In this work, an innovative method was proposed to doping Ag nanoparticles (Ag NPs) into glass ceramics (GC) via a "melt-freeze" method, then efficient and stable Ag-doped antibacterial ceramics (GC-xAg@BiOCl) were fabricated through facile in-situ HCl etching GC. Results indicate that the low Ag content (0.03 mol%) and high dispersion of Ag NPs are fully exposed and anchored on the surface, and constructed Schottky junction Ag/BiOCl contributed to antibacterial and photocatalytic activity. The degradation rates of norfloxacin and methylene blue by GC-0.25Ag@BiOCl can reach 71.0% and 55.3% under visible light irradiation, respectively. Moreover, The GC-0.25Ag@BiOCl exhibited significant antibacterial activity against Escherichia coli (E.coli) and Staphylococcus aureus (S. aureus), with E.coli at 7.3 log10 cfu/mL and S. aureus at 7.0 log10 cfu/mL completely inactivated under visible light irradiation. Additionally, the antibacterial mechanism and charge transfer mechanism were explored.

Effects of Ag Nanoparticles Impregnated Over Chitosan-Agarose Modified Magnetic Nanocomposite as an Efficient Reusable Nano Catalyst on Bone Regeneration in a Rat Calvarial Defect Model and Screening System

The development of multifunctional biomaterials with precise design and synthesis is desired for various fields of medicine and biology. Nanomaterials and nanotechnology have a huge potential to be applied and develop multifunctional and sophisticated nano- and biomaterials. In this study, we synthesized silver nanoparticles (AgNPs) and applied them into Chitosan-Agarosemodified magnetic nanocomposite to develop an efficient reusable Nano catalyst. The fabricated AgNPs were characterized using Transmission electron microscopy and results showed that AgNPs were partially spherical with uniform morphology and a size of 22±6 nm. Measuring the zeta potential showed that AgNPs possess a negative surface potential of around −27.7 mV which is desired for the stability of AgNPs. The AgNPs were incorporated into a Chitosan-Agarose modified magnetic nanocomposite and TEM and EDX analysis confirmed homogenous dispersion of AgNPs into the nanocomposite. The cell culture (in vitro) studies conducted using the MTT assay kit confirmed the biocompatibility of the fabricated nanocomposite. The animal study (the implantation of the nanocomposite in rat calvarial defect model) showed that the nanocomposite induced bone regeneration and filed the induced defect. These resultant findings suggested that the developed AgNPs-bearing nanocomposite can be applied as an efficient reusable Nano catalyst for bone regeneration.

Green Synthesis of MOF-Mediated pH-Sensitive Nanomaterial AgNPs@ZIF-8 and Its Application in Improving the Antibacterial Performance of AgNPs.

Herein, an emerging drug delivery system was constructed based on zeolite imidazole backbone (ZIF-8) to improve antibacterial defects of nanosilver (AgNPs), such as easily precipitated and highly cytotoxic. The homogeneous dispersion of AgNPs on ZIF-8 was confirmed by UV-Vis spectroscopy, FTIR spectroscopy, particle size analysis, zeta potential analysis, and SEM. The appropriate AgNPs loading ratio on ZIF-8 was screened through the cell and antibacterial experiments based on biosafety and antibacterial performance. The optimal environment for AgNPs@ZIF-8 to exert antibacterial performance was probed in the context of bacterial communities under different acid-base conditions. The potential mechanism of AgNPs@ZIF-8 to inhibit the common clinical strains was investigated by observing the biofilm metabolic activity and the level of reactive oxygen species (ROS) in bacteria. The successful piggybacking of AgNPs by ZIF-8 was confirmed using UV-Vis spectroscopy, FTIR spectroscopy, particle size analysis, zeta potential analysis, and SEM characterization methods. Based on the bacterial growth curve (0-24 hours), the antibacterial ability of AgNPs@ZIF-8 was found to be superior to AgNPs. When the mass ratio of ZIF-8 and AgNPs was 1:0.25, the selection of AgNPs@ZIF-8 was based on its superior antimicrobial efficacy and enhanced biocompatibility. Notably, under weakly acidic bacterial microenvironments (pH=6.4), AgNPs@ZIF-8 demonstrated a more satisfactory antibacterial effect. In addition, experiments on biofilms showed that concentrations of AgNPs@ZIF-8 exceeding 1×MIC resulted in more than 50% biofilm removal. The nanomedicine was found to increase ROS levels upon detecting the ROS concentration in bacteria. Novel nanocomposites consisting of low cytotoxicity drug carrier ZIF-8 loaded with AgNPs exhibited enhanced antimicrobial effects compared to AgNPs alone. The pH-responsive nano drug delivery system, AgNPs@ZIF-8, exhibited superior antimicrobial activity in a mildly acidic environment. Moreover, AgNPs@ZIF-8 effectively eradicated pathogenic bacterial biofilms and elevated the intracellular level of ROS.

Biocontrol of chocolate spot disease of broad bean (Vicia faba L.) caused by Botrytis fabae using biosynthesized reduced graphene oxide/silver nanocomposite

This study was demonstrated to investigate the effects of reduced graphene oxide/silver nanocomposite (rGO/AgNC) on controlling the chocolate spot disease of broad bean (Vicia faba L.) caused by Botrytis fabae. rGO/AgNC was green synthesized using the cell-free supernatant of Escherichia coli D8 in the presence of sunlight and room temperature. rGO/AgNC revealed a broad UV–vis absorption peak at 433 nm. Transmission electron microscopy (TEM) images of rGO/AgNC confirmed the presence of spherical-shaped silver nanoparticles (AgNPs) with an average size of 7–26 nm. Zeta analysis of rGO/AgNC displayed their positive charge (+18.9 mV) and the good dispersion of AgNPs on the surface of rGO. rGO/AgNC had good antifungal activity against B. fabae in a dose-dependent pattern. In vivo, rGO/AgNC-treatment study on faba bean plants showed the biocidal action of rGO/AgNC (150 μg/ml) against B. fabae and completely prevented the pathogen infection. In addition, there was an increase in total phenolic content, peroxidase, and polyphenol oxidase activity, and protein content of rGO/AgNC-treated plants. Plants treated with rGO/AgNC displayed a typical cell morphology in their ultrastructure, including cell membranes and chloroplasts with ellipsoidal shapes and large starch grains. These are all encouraging findings for the use of the biosynthesized rGO/AgNC as a safe and efficient antifungal agent against B. fabae.

Antioxidation Effect of Graphene Oxide on Silver Nanoparticles and Its Use in Antibacterial Applications.

Silver nanoparticles (AgNPs) have drawn great attention due to their outstanding antibacterial effect in a wide range of applications, such as biomass packaging materials, wound dressings, flexible sensors, etc. However, the oxidation of AgNPs limits the antibacterial effect. Firstly, the effects of pretreatment methods on the antibacterial property of AgNPs were investigated by the shake flask method and agar diffusion plate method. Secondly, graphene oxide/silver nanoparticle (GO/AgNPs) nanocomposite prepared by an in-situ growth method was used as antibacterial filler for polyacrylate emulsion via a blending method. The antibacterial mechanism of GO/AgNPs was revealed by comparing the actual contents of oxygen with the theoretically calculated contents of oxygen. Finally, the polyacrylate/graphene oxide/silver nanoparticles (PA/GO/AgNPs) composite emulsion was applied onto a leather surface using a layer-by-layer spraying method to improve the leather's antibacterial properties. The results showed that ultraviolet irradiation could better maintain the antibacterial property of AgNPs, while GO could improve the dispersibility of AgNPs and prevent their oxidation. The leather finished with the PA/GO/AgNPs-2 wt% composite emulsion showed the highest bacteriostatic rate of 74%, demonstrating its great potential in the application of antibacterial leather products.

A rapid, high-yield and bioinspired synthesis of colloidal silver nanoparticles using Glycyrrhiza glabra root extract and assessment of antibacterial and phytostimulatory activity.

Silver nanoparticles (AgNPs) have emerged as highly effective antimicrobial agents against multidrug-resistant (MDR) pathogens. This study aims to employ green chemistry principles for AgNP synthesis involving phytochemical-rich extract from Glycyrrhiza glabra roots. The approach highlights using renewable feedstocks, safer chemicals, minimum byproducts, and process scale-up. The synthesis of AgNPs was assessed using a surface plasmon resonance band at 420 nm, and structural properties were characterized using TEM, x-ray diffraction, Fourier-transform infrared spectroscopy, and X-ray photoelectron spectroscopy. This method enables the production of high-yield dispersions of AgNPs with desired physicochemical characteristics, including dark yellow solution, size (~20 nm), spherical to an oval shape, crystal structure, and stable colloidal properties. The antimicrobial activity of AgNPs was investigated against the MDR bacteria strains of gram-positive (Staphylococcus aureus) and gram-negative (Escherichia coli). This work reveals that the antimicrobial activity of AgNPs can be influenced by bacterial cell wall components. The results demonstrate the strong interaction between AgNPs and E. coli, exhibiting a dose-dependent antibacterial response. The green approach facilitated the safer, facile, and rapid synthesis of colloidal dispersions of AgNPs, providing a sustainable and promising alternative to conventional chemical and physical methods. Furthermore, the effect of AgNPs on various growth parameters, including seed germination, root and shoot elongation, and dry weight biomass, was assessed for mung bean seedlings. The results revealed phytostimulatory effects, suggesting the promising prospects of AgNPs in the nano-priming of agronomic seeds. RESEARCH HIGHLIGHTS: Glycyrrhiza glabra root extract enabled rapid, high-yield, and eco-friendly synthesis of silver nanoparticles (AgNPs). Spectrophotometric analysis examined the optical properties, scalability, and stability of AgNPs. Transmission electron microscopy provided insights into the size, shape, and dispersity of AgNPs. Scanning electron microscopy revealed significant damage to gram-negative bacterial cell morphology and membrane integrity. AgNPs were found to enhance seed germination, seedling growth, and biomass yield of Vigna radiata.

Fabrication of submicron linewidth silver grid/ionogel hybrid films for highly stable flexible transparent electrodes via asymmetric wettability template-assisted self-assembly

High-performance flexible transparent electrodes are the basis for the continuous upgrading of optoelectronic devices. Silver grids are attractive for replacing traditional indium tin oxide (ITO) as the premier transparent electrode materials, due to their high transmittance, excellent conductivity, and low cost. However, large linewidth and oxidation of silver grids are limiting the practical application of the resulting optoelectronic devices. Here, we report an effective and scalable solution-based method to prepare highly stable flexible transparent silver grid electrodes with submicron linewidth by the asymmetric wettability template-assisted self-assembly of silver nanoparticles (AgNPs), which is then encapsulated by a thin transparent conductive ionogel as protective layer. It is demonstrated that the linewidth of silver grids can be precisely controlled by the concentration of the AgNP dispersion. Wrapping with the ionogel nanolayer have no deterioration for conductivity and transmittance of the grid electrodes. The optimized hybrid grid electrodes exhibit low sheet resistance of 24.6 Ω sq−1 and high transparency of 99%. More importantly, the introduction of the iongel nanolayer endows the hybrid grid electrodes with excellent mechanical flexibility and thermal, electrical, and chemical stability. As a proof of concept demonstration, the submicron linewidth silver grid/ionogel hybrid films are successfully used to fabricate flexible smart windows and transparent touch panel. We envision that this work will shed new light on the development of next-generation optoelectronic applications which need ultrahigh resolution displays.

Synergistic effect of silver NPs immobilized on Fe3O4@L-proline magnetic nanocomposite toward the photocatalytic degradation of Victoria blue and reduction of organic pollutants.

The surface of magnetite (Fe3O4) nanoparticles was subject to modification through the incorporation of L-proline (LP) by simple co-precipitation method in which silver nanoparticles were deposited by in situ method, thereby yielding the Fe3O4@LP-Ag nanocatalyst. The fabricated nanocatalyst was characterized using an array of techniques including Fourier-transform infrared (FTIR), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), vibrating sample magnetometry (VSM), Brunauer-Emmett-Teller (BET), and UV-Vis spectroscopy. The results evince that the immobilization of LP on the Fe3O4 magnetic support facilitated the dispersion and stabilization of Ag NPs. The SPION@LP-Ag nanophotocatalyst exhibited exceptional catalytic efficiency facilitating the reduction of MO, MB, p-NP, p-NA, NB, and CR in the presence of NaBH4. The rate constants obtained from the pseudo-first-order equation were 0.78, 0.41, 0.34, 0.27, 0.45, 0.44, and 0.34 min-1 for CR, p-NP, NB, MB, MO, and p-NA, respectively. Additionally, the Langmuir-Hinshelwood model was deemed the most probable mechanism for catalytic reduction. The novelty of this study lies in the use of L-proline immobilized on Fe3O4 MNPs as a stabilizing agent for the in-situ deposition of silver nanoparticles, resulting in the synthesis of Fe3O4@LP-Ag nanocatalyst. This nanocatalyst exhibits high catalytic efficacy for the reduction of multiple organic pollutants and azo dyes, which can be attributed to the synergistic effects between the magnetic support and the catalytic activity of the silver nanoparticles. The easy recyclability and low cost of the Fe3O4@LP-Ag nanocatalyst further enhance its potential application in environmental remediation.

Silver nanoparticles-based thioureidophosphonate composites: Synthesis approach and their exploitation in 4-nitrophenol reduction

Two novel mono- and bis-thioureidophosphonate cores (referred by MTP & BTP, respectively) were facilely synthesized in ionic liquid conditions and incorporated with silver nanoparticles (Ag NPs) via in-situ reduction method giving two heterogeneous nanocatalysts, denoted as Ag NP/MTP and Ag NP/BTP, respectively. X-ray diffraction (XRD), ultraviolet-visible (UV–Vis), and high-resolution transmission electron microscopy (HR-TEM) tools were conducted for the as-fabricated Ag NP/TP nanocomposites revealing the good dispersion of Ag NPs in spherical black dots with average size ranges of (∼9.5–12.7 nm) and (∼17.0–22.5 nm) for Ag NP/MTP and Ag NP/BTP, respectively. The Fourier transform infrared (FT-IR) and X-ray photoelectron spectroscopy (XPS) techniques clarified that, MTP possessing (POPh, PO, C=S, HCO, and >NH) functionalities were participated in the reduction of Ag+ ions to Ag0 NPs. The catalytic properties of both Ag NP/TP nanocomposites were verified through the chemical conversion of 4-nitrophenol (4-NP) to less hazardous 4-aminophenol (4-AP) comparable to the slight catalytic reduction of Ag NPs-free TP derivatives. To assess the catalytic performance, some kinetic parameters such as rate constant (Kapp), normalized rate constant (Knor), and turnover frequency (TOF) were estimated at the highest concentration of 4-NP. Accordingly, Ag NP/MTP exhibited more remarkable catalytic activity and durability toward 4-NP reduction than that of Ag NP/BTP. The simple stereochemistry and accessibility of active sites for MTP tuned the surface function with Ag+ ions, affording more stable and regular Ag NPs over the same nanoparticle with BTP. Regarding Ag NP/MTP, catalytic improvement rates to 69%, 64%, and 69% were respectively recorded for Kapp, Knor, and TOF over Ag NP/BTP. Moreover, both nanocatalysts demonstrated good surficial stability through 10 consecutive cycles. Herein, this study has provided a new sustainable route for developing new TP-wrapped metal nanocomposites as robust and selective platforms in catalytic and environmental applications.

Phytochemical Synthesis of Silver Nanoparticles and Their Antimicrobial Investigation on Cotton and Wool Textiles.

The use of bio-based reagents for silver nanoparticle (AgNP) production has gained much attention among researchers as it has paved the way for environmentally friendly approaches at low cost for synthesizing nanomaterials while maintaining their properties. In this study, Stellaria media aqueous extract was used for silver nanoparticle phyto-synthesis, and the resulting treatment was applied to textile fabrics to test its antimicrobial properties against bacteria and fungi strains. The chromatic effect was also established by determining the L*a*b* parameters. For optimizing the synthesis, different ratios of extract to silver precursor were tested using UV-Vis spectroscopy to observe the SPR-specific band. Moreover, the AgNP dispersions were tested for their antioxidant properties using chemiluminescence and TEAC methods, and the phenolic content was evaluated by the Folin-Ciocâlteu method. For the optimal ratio, values of average size, 50.11 ± 3.25 nm, zeta potential, -27.10 ± 2.16 mV, and polydispersity index, 0.209, were obtained via the DLS technique and zeta potential measurements. AgNPs were further characterized by EDX and XRD techniques to confirm their formation and by microscopic techniques to evaluate their morphology. TEM measurements revealed cvasi-spherical particles with sizes in the range of 10-30 nm, while SEM images confirmed their uniform distribution on the textile fiber surface.

Aminopolymer-functionalized hollow carbon spheres incorporating Ag nanoparticles for electrochemical syngas production from CO2

Electrochemical CO2 reduction (CO2RR) to produce syngas (CO and H2) is a highly attractive way for achieving carbon neutrality. However, it remains a challenge due to the lack of high-efficiency electrocatalysts that enables controllable CO/H2 ratio syngas production. Herein, aminopolymer functionalized hollow carbon spheres incorporating Ag NPs (Ag-P@HCS) are developed, which function as active catalysts for syngas electrosynthesis. The introduction of aminopolymers results in finely improved dispersion of Ag NPs and increased CO2 adsorption of Ag-P@HCS, thereby altering its CO2RR performance. As a result, Ag-P@HCS achieves a 4.6-fold increase in the Faradaic efficiency of CO when compared to the amiopolymer-free analog (Ag-HCS) at − 0.8 V vs. RHE. More importantly, the controllable CO/H2 ratios (1.09 – 2.54) can be obtained for Ag-P@HCS over a wide potential window, which is capable of meeting the specific requirements for industrial production. This work demonstrates the potential of aminopolymer functionalization for designing high-performance CO2RR electrocatalysts.