Formation Of Ag Nanoparticles Research Articles

Metallo‐Surfactant Complex‐Assisted Biomimetic Synthesis of Silver Nanoparticles: Exploring Relativistic Effects in Catalytic and Sensing Applications

AbstractA biological reduction method for silver nanoparticles was employed using Cassia alata extract from plant leaves, which functions as a reducing agent and the metallo‐surfactant [Co(dqn)2(C12H27N)2]3+ (dqn = dipyrido[3,2‐f:2′,3′‐h]‐quinoxaline; C12H27N)2 = dodecylamine) acting as both stabilizing and capping agent. The ratio of Ag nanoparticles (AgNPs) formation was adjusted to be equal to the amount of AgNO3, along with variations in the amount of plant leaf extract, the metallo‐surfactant, pH, surrounding temperature, and the length of interaction periods. High‐resolution transmission electron microscopy (HRTEM), field emission scanning electron microscopy (FE‐SEM), energy‐dispersive spectroscopy (EDS), and energy‐dispersive X‐ray analysis (EDAX) were used to confirm the formation of AgNPs. The infrared results indicate the presence of hydroxyl, amine, and carboxylate groups in the extract plays a crucial role in the reduction process. Additionally, the metallo‐surfactant acts as a capping agent for the silver nanoparticles, preventing agglomeration. By adjusting the acidity of the solution and the quantity of the additive metallo‐surface active agent utilized, the size of AgNPs can be precisely regulated. The relativistic effects observed in this metallo‐surfactant‐assisted silver nanoparticle demonstrate excellent reduction capabilities for nitro compounds, effective dye degradation, and mercury sensing applications.

Crystallization and Optical Behaviour of Nanocomposite Sol-Gel TiO2:Ag Films.

Sol-gel spin coating method was employed for depositing TiO2 and Ag-doped TiO2 films. The effects of Ag doping and the annealing temperatures (300-600 °C) were studied with respect to their structural, morphological, vibrational, and optical properties. Field Emission Scanning Electron microscopy (FESEM) investigation exhibited the grained, compact structures of TiO2-based films. Ag incorporation resulted in a rougher film surface. X-ray diffraction (XRD) results confirmed the formation of Ag nanoparticles and AgO phase, along with anatase and rutile TiO2, strongly depending on Ag concentration and technological conditions. AgO fraction diminished after high temperature annealing above 500 °C. The vibrational properties were characterized by Fourier Transform Infrared (FTIR) spectroscopy. It was found that silver presence induced changes in IR bands of TiO2 films. UV-VIS spectroscopy revealed that the embedment of Ag NPs in titania matrix resulted in higher absorbance across the visible spectral range due to local surface plasmon resonance (LSPR). Ag doping reduced the optical band gap of sol-gel TiO2 films. The optical and plasmonic modifications of TiO2:Ag thin films by the number of layers and different technological conditions (thermal and UV treatment) are discussed.

Harnessing in-situ oxidation of nanostructured mxene to modulate the electronic structure for improved selectivity for electrochemical carbon dioxide reduction

The electrochemical CO2 reduction reaction (CO2RR) is a promising approach to valorizing CO2. Ti3C2TX as a support material has received significant interest in enhancing CO2RR performance for tuning the electronic structure. However, there has been relatively less focus on changes to the Ti3C2TX electronic structure induced by loading catalysts onto the Ti3C2TX. Because Ti3C2TX has an intrinsic activity for both CO2RR and the competitive hydrogen evolution reaction (HER), electronic structure changes can affect the balance between CO2RR and HER selectivity. Therefore, tuning the electronic structure of Ti3C2TX can control the competition between CO2RR and HER and tune the selectivity and activity. Herein, we report that Ti3C2TX’s electronic structure can be tuned by the Ag+ loading method via redox interactions, tuning the reaction selectivity and activity for CO2RR. To illustrate this effect, we compare the CO2RR performance of in-situ formed Ag nanoparticles (NPs) on Ti3C2TX (0.9Ag-IS-Ti3C2TX) with physically mixed Ag NPs and Ti3C2TX (0.9Ag/P/Ti3C2TX). Here, ‘0.9’ refers to the molar ratio between Ag precursor and Ti3C2Tx, and ‘IS’ vs. ‘P’ refers to in-situ formed vs. physically mixed Ag NPs. 0.9Ag-IS-Ti3C2TX demonstrates a higher oxidation state for Ti and a higher proportion of Ti-O bonds than 0.9Ag/P/Ti3C2TX. Compared to 0.9Ag/P/Ti3C2TX, 0.9Ag-IS-Ti3C2TX exhibits higher CO Faradaic efficiency (FE), rising from 8.1 % with a partial current density of −2.0 mA cm−2 to 49.6 % with a partial current density of −20.1 mA cm−2 at −1.4 V vs. RHE (reversible hydrogen electrode). To harness this effect, we demonstrate control over the CO: H2 ratio of syngas formed from CO2RR over our Ti3C2TX-supported catalysts. Further electrochemical anodic oxidation experiments reveal the critical oxidation potential of Ti3C2TX (0.8 V vs. RHE) and show that HER can be partially suppressed by partial oxidation of Ti3C2TX. This work highlights the importance of considering the changes in Ti3C2TX (and other) supports when supporting catalysts for CO2RR and other electrochemical reactions.

Plasmonic Ag Nanoparticles on SiC for Use as SERS Substrate and in Integrated Optical Sensors for Bio-Chemical Applications

Development of optical chemical sensors for the detection of specific toxic chemicals at ultratrace levels and analysis of complex mixtures is crucial for new green and safe technologies [1, 2]. Metallic structures confined at the nanoscale acquire interesting properties such as strongly localizing E fields on their surfaces through Plasmonic Resonance under stimuli of light at certain wavelengths. This nanostructures are called plasmonic structures [3–5]. This effect is exploited to amplify the optical signal obtained by the molecules of interest, located near plasmonic structures [3, 6]. Purpose of the work is the development of innovative, easy to manufacture and cheap optical active layer consisting of Plasmonic Ag Nanoparticles on a Wide Band Gap semiconductor material such as Silicon Carbide to be used as substrate for Surface Enhanced Raman Scattering or for the fabrication of integrated optical sensor for remote chemical and biological applications. In this contest, the phenomenon of Ag thin film thermal dewetting on SiC substrate was implemented to develop a simple nanoparticles synthetic approach. Scanning Electron Microscopy confirmed the formation of Ag nanoparticles by thermal annealing of thin silver film. 4-MBA was used as probe molecule for SERS phenomenon investigation. The formation of a covalent bond between the silver nanostructures, acting as plasmonic "hot spots", and the species of interest enable its detection at very low concentrations, in the range of 10-5 M or less, in both Raman and UV-Vis configurations.

Continuous On‐Chip Synthesis of Ag Nanoparticles Assisted by Resonant Microwave Heating Using a Post‐Wall Waveguide

Microfluidics made of dimethylpolysiloxane were developed for chemical synthesis using microwave heating at 24.125 GHz, and microwave efficiency was enhanced by the microwave resonance effect. In addition, the device was fabricated using a mold created using a 3D printer to reduce production costs. The microchip structure comprised a post‐wall waveguide and a microchannel that passed through the waveguide. This post‐wall waveguide also comprises metal columns (post‐wall) instead of a conductor side wall, and easily introduces microchannels through the gaps between the metal columns. The waveguide length was adjusted to achieve a resonance frequency of 24 GHz using an electromagnetic wave simulation, assuming that the microchannel was filled with pure water. Microwaves with an input power of 4 W caused a maximum temperature increase of 93 °C; this result is ~10 °C higher than that of a microchip with non‐resonant structure. In this study, Ag nanoparticles were synthesized using a chemical reaction induced by microwave irradiation of a chip flow system. Owing to irradiating the mixing reagent with microwaves of an input power of 4 W while controlling the flow rate at 0.7 μl/min, the formation of Ag nanoparticles with an average particle size of ~19.2 ± 2.4 nm was demonstrated by absorbance measurements and dynamic light scattering. It is expected that microwave microfluidics enhanced by the resonance effect will substantialize nanoparticle synthesis and high‐efficiency automated chemical synthesis combined with multichemical unit operations. © 2024 Institute of Electrical Engineers of Japan and Wiley Periodicals LLC.

Gallium Nanostructure‐Based Microneedle Patch for Multidrug‐Resistant Bacterial Wound Healing: Enhanced Metal Release and NIR Photothermal Effect

AbstractBacterial infections, especially caused by multidrug‐resistant bacteria, pose a big challenge to the healthcare system. As a group of historic agents, metals with broad‐spectrum antibacterial activity are regarded as promising alternatives to tackle antibiotic resistance. Among them, gallium ions have presented encouraging antibacterial effects in research and preclinic studies. However, utilization of gallium ions has difficulty in achieving high targeting and long‐term effectiveness. With the renaissance of liquid metal, here, a novel and facile antibacterial gallium nanostructure is proposed in which polydopamine‐modified gallium nanocore serves as an ion reservoir for enhanced metal ion release and the surface also permits secondary reaction, allowing for in situ formation of Ag nanoparticles to improve the antibacterial property, ROS generation, and photothermal performance. Notably, ≈100% bacterial killing efficacy can be achieved when combined with NIR laser irradiation. The in vivo treatment results of methicillin‐resistant Staphylococcus aureus (MRSA)‐infected mice demonstrate that the microneedle patch loaded with nanoparticles exhibits outstanding bacterial elimination and inflammation alleviation, and promotes angiogenesis and collagen deposition, further accelerating wound healing. This gallium‐based nanostructure offers an effective nanoplatform for antibacterial treatments and combinatory strategies, which holds significant promise for refractory multidrug‐resistant bacteria and related infections.

Green synthesis of Carica papaya mediated silver nanoparticles: Characterization, antibacterial activity, and bioelectricity generation for sustainable applications in nanotechnology

This study presents a sustainable method for synthesizing silver nanoparticles (Ag NPs) using green Carica papaya extract (CPE) as a reducing and stabilizing agent. The green synthesis minimizes environmental impact and utilizes bioactive compounds in Carica papaya (CP), offering an economical and sustainable alternative. The goal is to employ CPE for the eco-friendly synthesis of Ag NPs, followed by comprehensive characterization, antibacterial evaluation, cytotoxicity against brine shrimp, and examination of bioelectricity generation. Locally sourced CP was boiled in deionized water, then cooled and filtered twice. The bio-reduction of silver ions to Ag NPs was confirmed by a color change when 45 mL of 0.005 M AgNO3 was mixed with 5 mL of CPE. Characterization through UV–vis absorption spectrophotometry (UV), X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), Field emission scanning electron microscopy (FESEM), Energy dispersive X-ray spectroscopy (EDX), Transmission electron microscopy (TEM), and Gas chromatography-mass spectrometry (GC–MS) analysis confirms the successful formation and consistent size distribution of Ag nanoparticles. CPE is a crucial reducing agent, as evidenced by a distinct UV-visible peak at 422 nm. X-ray crystal analysis verifies highly crystalline Ag NPs with a face-centered cubic lattice structure. The d-spacing values in SAED images are consistent with the results obtained from XRD. Antimicrobial effectiveness against Escherichia coli and Staphylococcus epidermidis is demonstrated. The study explores the bioelectricity generation potential of CPE-synthesized Ag NPs, indicating promising prospects for sustainable energy solutions. Preliminary experiments show the ability of the nanoparticles to catalyze bio-electrochemical reactions. This dual-benefit study underscores CPEs role in antibacterial properties and bioelectricity generation, laying the groundwork for further research in sustainable nanotechnology applicable to healthcare and energy sectors and contributing to the advancement of environmentally friendly technologies.

Utilizing Biomolecule-Rich Citrus Fruit Waste as a Medium for the Eco-Friendly Preparation of Silver Nanoparticles with Antimicrobial Properties

An ample amount of fruit waste is generated as agro-industrial waste, leading to significant nutritional, economic, and environmental challenges. Fruit peels are rich in many valuable bioactive compounds with the potential for developing nanoparticles. This study examined fresh juices of two citrus fruit peel wastes (Citrus sinensis: C. sinesis and Citrus limon: C. limon) for antioxidants and total protein. Then, we investigated their ability to produce silver nanoparticles, which were further analyzed for anti-microbial activity against thirteen pathogenic microbes. Both Citrus peel juices were rich in secondary metabolites. The formation of Ag nanoparticles was initially confirmed by UV-vis spectroscopy, with peaks at 400 nm for C. sinensis peel Ag nanoparticles and 430 nm for C. limon peel Ag nanoparticles. Further characterization was conducted using zeta sizer, zeta potential, Transmission Electron Microscopy (TEM), Scanning Electron Microscope (SEM), Energy-dispersive X-ray spectroscopy (EDX) and Fourier transform infrared (FTIR) spectroscopy. The antimicrobial activity was tested using the well diffusion method against 11 bacterial strains (five Gram-positive and six Gram-negative) and two fungal strains of Candida. TEM and SEM results revealed a spherical shape, with an average diameter of about 13 nm for C. sinensis and 21 nm for C. limon Ag. EDX confirmed the presence of silver in both nanoparticles. The FTIR spectrum of the extract indicated the presence of biomolecules, which facilitated the reduction and capping of the synthesized Ag nanoparticles. The prepared nanoparticles showed remarkable antimicrobial activity, but the nanoparticles from C. sinensis exhibited stronger antibacterial properties because of their smaller size. Citrus peel waste is a suitable medium for the eco-friendly production of silver nanoparticles.

UV-Catalyzed TiO2-Based Optofluidic SERS Chip for Three Online Strategies: Fabrication, Detection, and Self-Cleaning.

We developed an optofluidic surface-enhanced Raman scattering chip capable of online fabrication, online molecular detection, and online self-cleaning. In this chip, we harnessed UV light to successfully reduce an AgNO3 solution, resulting in the formation of Ag nanoparticles on carbon fiber cloth coated with titanium dioxide (TiO2). This innovative approach enabled the online fabrication of AgNPs@TiO2-CFC SERS structures. By introducing target molecules into our optofluidic SERS chip, we achieved online molecular Raman detection. Furthermore, by leveraging the UV light-induced self-cleaning properties of TiO2, we achieved continuous online self-cleaning of the molecules. To verify the feasibility and stability of our method, we conducted multiple experiments for online detection and self-cleaning. Experimental results demonstrated impressively low detection limits of 10-8 mol/L for crystal violet and 10-9 mol/L for rhodamine 6G, with an enhancement factor as high as 1.4 × 106. Additionally, we successfully applied our method to polycyclic aromatic hydrocarbons like pyrene.

Green synthesis of silver nanoparticles decorated on graphene oxide for crystal violet dye removal

In this study, we demonstrate a facile and environmentally benign method for the synthesis of Ag nanoparticles using a green reducing agent and their subsequent deposition onto GO sheets. The synthesized GO@Ag nanocomposite was characterized using various analytical techniques such as FTIR, XRD, FESEM, EDX and BET. The results confirmed the successful formation of cubic Ag nanoparticles with diameter 30–40 nm on the GO surface. The theoretical surface area of GO@Ag was found to be 89 m2/g. The adsorption efficiency of GO@Ag nanocomposite toward CV dye was evaluated through batch adsorption experiments. The above experimental results revealed that CV adsorption on to the GO@Ag surface was pH dependent and maximum adsorption capacity was found to be 48.78 mg/g at pH = 8. The adsorption process followed pseudo-second-order kinetics and Langmuir isotherm models, indicating monolayer adsorption with chemisorption as the rate-limiting step. Furthermore, the recyclability and stability of the nanocomposite were assessed through multiple adsorption-desorption cycles, demonstrating its potential for practical applications in wastewater treatment for the removal of cationic dyes. The mechanism of CV adsorption on to the GO@Ag surface mainly involves electrostatic attraction and π-π interaction.

One‐step synthesis of a spongy flexible substrate for surface enhanced Raman spectroscopy comprising a silver nanoparticles‐loaded poly(amidoamine) dendrimer crosslinked with glutaraldehyde

AbstractA composite comprising a silver nanoparticles‐loaded poly(amidoamine) (PAMAM) dendrimer crosslinked with glutaraldehyde (PAMAM/AgNPs) is synthesized using a one‐step method under vortex at room temperature. The structure of glutaraldehyde‐crosslinked PAMAM dendrimer is characterized using FTIR and high‐resolution magic angle spinning–carbon 13 nuclear magnetic resonance (HRMAS 13C NMR) spectroscopy. The crosslinking structure ensures the uniformity and stability of the Ag nanoparticles, and the flexibility of the PAMAM/AgNPs composite. X‐ray diffraction (XRD) analysis and energy dispersive spectroscopy (EDS) confirm the formation of Ag nanoparticles in the PAMAM/AgNPs composite. Scanning electron microscopy (SEM) and three‐dimensional (3D) micro‐Raman images reveal the coarsely porous 3D micro‐structure of the PAMAM/AgNPs composite. This unique micro‐3D architecture provides the PAMAM/AgNPs composite with spongy flexibility and a swab‐like nature, which is advantageous for the rapid and effective absorption of liquid samples on the surfaces of objects. Surface enhanced Raman spectroscopy (SERS) indicates that the detection limits of both rhodamine 6G (R6G) and thiram are 1.0 × 10−5 mol L−1, and the SERS enhancement factor of R6G is determined to be 1.35 × 104. The spongy flexible PAMAM/AgNPs SERS substrate therefore has potential for use in Raman active compound detection.

Insights on the effect of process conditions on the optical properties of silver ion exchanged soda-lime silicate glass

The effects of ion exchange time and temperature on the optical properties and plasmonic response of silver ion exchanged soda-lime silicate glass were investigated using scanning electron microscopy (SEM) in energy dispersive spectrometry (EDS) configuration, m-lines spectroscopy, photoluminescence (PL) spectroscopy, and UV–visible absorption spectroscopy. SEM analyses in EDS mode provided profiles of silver oxide molar concentration. These profiles were directly correlated to the silver diffusion coefficient using an adjustment procedure. The effective indices of ion exchanged glasses measured by the standard prism coupling technique (m-lines) allowed access to refractive index distributions in ion exchange regions. These ion-exchanged glasses underwent evaluation to determine their potential suitability for use in multimode planar systems. The PL results acquired after ion exchange demonstrated that the creation of Ag0 atoms from Ag+ ions was responsible for the decline and quenching of PL intensity at ion exchange times and temperatures increase. Silver nanoparticles were generated in the samples subjected to ion exchange at 480 °C without the need for post-exchange treatments. The emergence of the surface plasmon resonance band around 427 nm in the optical absorption spectra confirmed the formation of Ag nanoparticles in annealed glasses. Estimates of the UV–visible absorption spectra indicated an average size of silver nanoparticles ranging from 1.8 to 2.4 nm.

Phyto-mediated synthesis of Ag, ZnO, and Ag/ZnO nanoparticles from leave extract of Solanum macrocarpon: Evaluation of their antioxidant and anticancer activities

Silver, zinc oxide, and silver/zinc oxide nanocomposites were prepared from the facile green process using Solanum macrocarpon leave extract. Ag and ZnO nanoparticles (NPs) were composited with the aim of enhancing the synergy for improved antioxidant and anticancer activities. In the synthesis process, the formation of Ag NPs was initially observed by a colour change and was confirmed by the appearance of surface plasmon resonance (SPR) bands. Based on the crystallographic analysis of the diffraction patterns, the phyto-capped silver NPs possessed a crystalline character, featuring a lattice structure of face-centered cubic (FCC) and an estimated crystallite size of around 7.2 nm. The formation of a hexagonal crystal structure of spherical morphology was confirmed for the ZnO, while the Ag/ZnO composite showed additional planes due to the silver nanoparticles in the cubic phase. The scavenging activities of 2,2-Diphenyl-1-picrylhydrazyl (DPPH) free radicals and their anticancer potency on normal HEK and cancerous HELA cells were examined in comparison to standard drugs. They demonstrated remarkable IC50 values that were better than the control drugs. This study provides helpful insight into the synergy between Ag and ZnO nanoparticles for the possible development of new anticancer and antioxidant agents.

Thiazole-Based Silver Ion Sensor for Sequential Colorimetric Visualization of Epinephrine in the Brain Tissues of an Alzheimer's Disease Model of Mouse.

A thiazole-based probe, N'-((2-aminothiazol-5-yl)methylene)benzohydrazide (TBH), has been efficiently synthesized and characterized for the selective and sensitive detection of the neurotransmitter epinephrine (EP). The sensing strategy is based on the use of TBH for sequential colorimetric sensing of Ag+ and EP via in situ formation of Ag nanoparticles (Ag NPs) from the TBH-Ag+ complex. The generated Ag NPs lead to a bathochromic shift in absorption maximum and a change in color of the solution from light brown to reddish brown. TBH-Ag+ shows remarkable selectivity toward EP versus other drugs, common cations, anions, and some biomolecules. Moreover, TBH-Ag+ has a low detection limit for EP at 1.2 nM. The coordination of TBH-Ag+ has been proposed based on Job's plot, Fourier transform infrared spectroscopy (FT-IR), high-resolution mass spectrometry (HRMS), 1H NMR titration, X-ray photoelectron spectroscopy (XPS), energy-dispersive X-ray analysis (EDAX), and density functional theory (DFT) studies. The composition and morphology of the generated Ag NPs have been analyzed by XPS, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and dynamic light scattering (DLS). The proposed sensing mechanism for EP has been supported by XPS of Ag after the reaction. Further, the sensitivity of TBH-Ag+ toward EP in brain tissues of an Alzheimer's disease model of mouse has been evaluated. A thorough comparison was done for evaluation of the proposed method.

Hybrid Materials Obtained by Immobilization of Biosynthesized Ag Nanoparticles with Antioxidant and Antimicrobial Activity.

Ag nanoparticles (AgNPs) were biosynthesized using sage (Salvia officinalis L.) extract. The obtained nanoparticles were supported on SBA-15 mesoporous silica (S), before and after immobilization of 10% TiO2 (Degussa-P25, STp; commercial rutile, STr; and silica synthesized from Ti butoxide, STb). The formation of AgNPs was confirmed by X-ray diffraction. The plasmon resonance effect, evidenced by UV-Vis spectra, was preserved after immobilization only for the sample supported on STb. The immobilization and dispersion properties of AgNPs on supports were evidenced by TEM microscopy, energy-dispersive X-rays, dynamic light scattering, photoluminescence and FT-IR spectroscopy. The antioxidant activity of the supported samples significantly exceeded that of the sage extract or AgNPs. Antimicrobial tests were carried out, in conditions of darkness and white light, on Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli and Candida albicans. Higher antimicrobial activity was evident for SAg and STbAg samples. White light increased antibacterial activity in the case of Escherichia coli (E. coli) and Pseudomonas aeruginosa (P. aeruginosa). In the first case, antibacterial activity increased for both supported and unsupported AgNPs, while in the second one, the activity increased only for SAg and STbAg samples. The proposed antibacterial mechanism shows the effect of AgNPs and Ag+ ions on bacteria in dark and light conditions.

Green Synthesis of Ag/Mg(OH)2 Nanocomposite from Potato Peel Extract (Solanum tuberosum) and Its Antioxidant Activity

Potato peel extract (PPE) is a rich source of polyphenols which could be used as reducing agents for the green synthesis of nanocomposites. The project aims to synthesize Ag/Mg(OH)2 nanocomposites (NCs) by using PPE and investigate its antioxidant activity. The phytochemicals in peel extract act as reducing, stabilizing, and capping agents in the reduction of precursor salts. SEM-EDX analyses of the bio-synthesized Ag/Mg(OH)2 NCs show the formation of Ag nanoparticles (NPs) on the surface of Mg(OH)2 carriers with various sizes in the nanoscale, while XRD patterns suggest the existence of Mg(OH)2 hexagonal crystalline structure. The antioxidant activity of Ag/Mg(OH)2 NCs was assessed through the DPPH free radical scavenging assay with IC50 values between 1.3 and 1.4 mg/mL. Compared to various plant-based Ag NPs, such values are remarkably closer to the IC50 of the standard ascorbic acid (0.6 mg/mL), promoting PPE-based Ag/Mg(OH)2 as an effective and ecofriendly antioxidant.

Water‐soluble astaxanthin and silver enriched poly(vinyl alcohol)/silk fibroin crosslinking electrospun nanofiber for wound dressing

AbstractThe aim of this work is to fabricate a novel electrospun poly(vinyl alcohol) (PVA)/silk fibroin (SF) nanofibrous membrane containing astaxanthin (ASTA) and silver (Ag) nanoparticles as potential wound dressing. Since ASTA is typically liposoluble, the bioavailability could be greatly enhanced by improving its hydrophilicity. The antioxidant performance of eletrospun membrane is verified by ABTS radical scavenging assays. The beadless fibers could be fabricated at 16 kV when PVA (12, wt%) is blended with SF (6, wt%). In addition, the membrane is carefully chemically crosslinked by comparing the efforts (i.e., mechanical strength and water resistance) of glutaraldehyde dipping and vapor treatment. The morphology of the electrospun membrane is observed by scanning electron microscopy and optical microscope. The formation of Ag nanoparticles, which provides the membranes antibacterial properties, is also confirmed by energy dispersive spectroscopy and inhibition zone test. Meanwhile, the PVA/SF/ASTA/Ag compound membrane is characterized by Fourier transform infrared spectroscopy, x‐ray diffraction, thermo gravimetric analysis, differential thermal analysis, and water contact angle. The releasing of ASTA is also measured, and kinetic data are adjusted by Higuchi models. Finally, the biocompatibility is confirmed by in vitro cell staining experiments and in vivo rat models.

Smart 3D Ag-decorated TiO2 Nanostructure: An advanced synergistic SERS substrate for trace detection of analytes with diverse natures

Designing surface-enhanced Raman scattering (SERS) substrates that combine multiple advanced features in synergy is highly desirable for the SERS technique, however, it has been a long-standing challenge due to inherent trade-offs in feature selection. For instance, while nanoplasmonic surface functionalization bolsters attraction to target analytes, it simultaneously introduces barriers to direct contact. Similarly, the intrinsic hydrophilic or hydrophobic nature of substrates often limits their sensing effectiveness across a wide range of analyte types. Here, we demonstrate a smart 3D Ag-decorated TiO2 nanostructure, an advanced synergistic SERS substrate, created by controlling the formation of Ag nanoparticles on functionalized TiO2 nanomaterials, which integrates four unique features: uniform hotspot distribution, efficient analyte trapping, accessible plasmonic surfaces, and dual-phase detection. This design brings unachieved sensor efficiency across a diverse array of analytes with varying sizes and hydrophobicity. Moreover, our design exhibits a novel dual-phase detection capability within mixtures of hydrophilic and hydrophobic analytes. As a proof-of-concept, our results highlight the potential of designing SERS substrates with multiple advanced features that work synergistically, enabling trace detection of a broader range of analyte types in various environments. More broadly, we anticipate that this work paves the way for the development of other nanomaterials that are capable of attracting diverse molecules while retaining key features such as accessible plasmonic surfaces and wide-area ordered hotspot distribution. Such nanomaterials could be powerful for advanced applications in hotspot engineering, surface analysis, catalysis, and plasmon-mediated reactions.

Structure and optical characterization of chitosan-chitin/Ag nanocomposite thin films

Chitin and its derivatives are common natural polymers that are widely used in various technological fields. In recent years, considerable attention has been paid to the preparation of polymer nanocomposites based on metal nanoparticles (NPs). Chitin/chitosan-based composites due to high antibacterial activity are suitable for application in related food storage, textile industries. This paper presents an effective and simple method of obtaining chitosan-chitin copolymer/Ag nanocomposites with an extremely high content of metal nanoparticles. The structure and morphology of the synthesized nanocomposites were investigated using X-ray diffractometry, Fourier-transform infrared spectroscopy, electron microscopy, and their optical properties were studied using UV-VIS spectroscopy as well as spectral ellipsometry. It was ascertained that the resulting nanocomposite films are characterized by a uniform distribution of spherical silver nanoparticles, the sizes of which increase (from 55 up to 143 nm) with increasing the Ag+-ions concentration in the reaction mixtures. The optical absorption spectra of nanocomposites are characterized by the presence of an absorption maximum within the range 458…525 nm, which confirms the formation of Ag NPs. A monotonous increase in the values of the energies of optical transitions was observed in the process of increasing the average size of NPs

Gelation of acrylic acid with Ag+ and conversion to Ag nanoparticle as potential system for biomedical applications

Silver (Ag) has been used to cross-link poly (acrylic acid) (PAAc) to obtain antibacterial nanocomposite hydrogel for controlled drug delivery systems. Ag+/PAAc composite hydrogel was prepared by free radical aqueous polymerization of acrylic acid (AAc) using potassium persulfate (KPS) as the initiator in the presence of silver nitrate (AgNO3). Sodium borohydride (NaBH4) was used to reduce the Ag ions present within the hydrogel matrix to generate Ag nanoparticles (Ag NPs). Transmission electron microscopy (TEM) characterization of the sample indicated the formation of Ag nanoparticles that distributed uniformly in the PAAc networks. UV–visible spectrophotometry showed an absorption peak at 425 nm that attribute to the well-known surface Plasmon resonance of the Ag bound in NPs. X-ray diffraction (XRD) pattern showed the appearance of some peaks corresponding to the face-centered cubic (f.c.c.) Ag phase. Energy dispersive spectroscopy (EDS) studies revealed that Ag NPs are successfully formed inside the Ag+/PAAc composite hydrogel. The gelation and crosslinking of PAAc chains with Ag+ by strong interactions between Ag cations and polyanions, deprotonated carboxylic groups of PAAc were identified from the Fourier transform infrared (FTIR) spectrogram. Field emission scanning electron microscopy (FESEM) exhibited an interconnected porous structure with an average pore size of about 10 μ for composite hydrogel that can absorb 440 g water/g dried sample. Dried samples were also loaded with amoxicillin and antibiotic release was studied. The antimicrobial activity of the Ag+ and Ag-NPs hydrogels was tested against Staphylococcus aureus, Bacillus cereus, Pseudomonas aeruginosa and Escherichia coli.