Facile and green fabrication of electrospun poly(vinyl alcohol) nanofibrous mats doped with narrowly dispersed silver nanoparticles

Development of Sustainable Hydrophilic Azadirachta indica Loaded PVA Nanomembranes for Cosmetic Facemask Applications

Nanofiber-based facial masks have attracted the attention of modern cosmetic applications due to their controlled drug release, biocompatibility, and better efficiency. In this work, Azadirachta indica extract (AI) incorporated electrospun polyvinyl alcohol (PVA) nanofiber membrane was prepared to obtain a sustainable and hydrophilic facial mask. The electrospun AI incorporated PVA nanofiber membranes were characterized by scanning electron microscope, Ultraviolet-visible spectroscopy (UV-Vis) drug release, water absorption analysis, 2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenging, and antibacterial activity (qualitative and quantitative) at different PVA and AI concentrations. The optimized nanofiber of 376 ± 75 nm diameter was obtained at 8 wt/wt% PVA concentration and 100% AI extract. The AI nanoparticles of size range 50~250 nm in the extract were examined through a zeta sizer. The water absorption rate of ~660% and 17.24° water contact angle shows good hydrophilic nature and water absorbency of the nanofiber membrane. The UV-Vis also analyzed fast drug release of >70% in 5 min. The prepared membrane also exhibits 99.9% antibacterial activity against Staphylococcus aureus and has 79% antioxidant activity. Moreover, the membrane also had good mechanical properties (tensile strength 1.67 N, elongation 48%) and breathability (air permeability 15.24 mm/s). AI-incorporated nanofiber membrane can effectively be used for facial mask application.

Advances in Electrostatic Spinning of Polymer Fibers Functionalized with Metal-Based Nanocrystals and Biomedical Applications

Considering the metal-based nanocrystal (NC) hierarchical structure requirements in many real applications, starting from basic synthesis principles of electrostatic spinning technology, the formation of functionalized fibrous materials with inorganic metallic and semiconductor nanocrystalline materials by electrostatic spinning synthesis technology in recent years was reviewed. Several typical electrostatic spinning synthesis methods for nanocrystalline materials in polymers are presented. Finally, the specific applications and perspectives of such electrostatic spun nanofibers in the biomedical field are reviewed in terms of antimicrobial fibers, biosensing and so on.

In situ fabrication of silver/polyimide composite films with enhanced heat dissipation

In this study, silver/polyimide (Ag/PI) composite films with enhanced heat dissipation properties were prepared. Ag was formed in situ by reducing AgNO₃ at various locations according to the reduction method. Two different types of soluble PIs capable of solution processing were used, namely Matrimid and hydroxy polyimide (HPI). Unlike Matrimid with bulky substituents, HPI with polar hydroxy groups formed ion-dipole interactions with Ag ions to form Ag particles with uniform size distribution. The location and distribution of Ag particles affect the heat emission characteristics of the composite films, resulting in better heat dissipation properties with the thermally and photochemically reduced Ag/HPI films having more Ag particles distributed inside of the films than the chemically reduced films.

Electrospun Nanofibers/Nanofibrous Scaffolds Loaded with Silver Nanoparticles as Effective Antibacterial Wound Dressing Materials

The treatment of wounds is expensive and challenging. Most of the available wound dressings are not effective and suffer from limitations such as poor antimicrobial activity, toxicity, inability to provide suitable moisture to the wound and poor mechanical performance. The use of inappropriate wound dressings can result in a delayed wound healing process. Nanosize range scaffolds have triggered great attention because of their attractive properties, which include their capability to deliver bioactive agents, high surface area, improved mechanical properties, mimic the extracellular matrix (ECM), and high porosity. Nanofibrous materials can be further encapsulated/loaded with metal-based nanoparticles to enhance their therapeutic outcomes in wound healing applications. The widely studied metal-based nanoparticles, silver nanoparticles exhibit good properties such as outstanding antibacterial activity, display antioxidant, and anti-inflammatory properties, support cell growth, making it an essential bioactive agent in wound dressings. This review article reports the biological (in vivo and in vitro) and mechanical outcomes of nanofibrous scaffolds loaded with silver nanoparticles on wound healing.

Recent developments in antimicrobial and antifouling coatings to reduce or prevent contamination and cross-contamination of food contact surfaces by bacteria

Illness as the result of ingesting bacterially contaminated foodstuffs represents a significant annual loss of human quality of life and economic impact globally. Significant research investment has recently been made in developing new materials that can be used to construct food contacting tools and surfaces that might minimize the risk of cross-contamination of bacteria from one food item to another. This is done to mitigate the spread of bacterial contamination and resultant foodborne illness. Internet-based literature search tools such as Web of Science, Google Scholar, and Scopus were utilized to investigate publishing trends within the last 10 years related to the development of antimicrobial and antifouling surfaces with potential use in food processing applications. Technologies investigated were categorized into four major groups: antimicrobial agent-releasing coatings, contact-based antimicrobial coatings, superhydrophobic antifouling coatings, and repulsion-based antifouling coatings. The advantages for each group and technical challenges remaining before wide-scale implementation were compared. A diverse array of emerging antimicrobial and antifouling technologies were identified, designed to suit a wide range of food contact applications. Although each poses distinct and promising advantages, significant further research investment will likely be required to reliably produce effective materials economically and safely enough to equip large-scale operations such as farms, food processing facilities, and kitchens.

Controlled release of monodisperse silver nanoparticles via in situ cross-linked polyvinyl alcohol as benign and antibacterial electrospun nanofibers

A facile methodology was explored by using glutaraldehyde as a cross-linking reagent for in situ modification of polyvinyl alcohol (PVA) electrospun nanofibers doped with monodisperse silver nanoparticles (AgNPs) via the one-pot reactions. The hydroxyl groups along the PVA molecule chains can serve as both the reactive sites and stabilizers for AgNPs. Meanwhile, the cross-linking degree can be easily tuned by controlling the charged amounts of glutaraldehyde to obtain either partial or cured cross-linked PVA nanofibrous mats doped with AgNPs. It was revealed that such different cross-linking degrees could effectively control the release contents and rates of the embedded Ag to the surrounding aqueous solution. Furthermore, such release behavior was also found to be pH-responsive and acid-labile due to the formation of acetal groups during the cross-linking reactions. Besides both the partial and cured cross-linked PVA doped with Ag nanoparticles can still bear good antibacterial efficacy against S. aureus while have low cytotoxicity against mouse embryo fibroblasts (NIH3T3), human embryonic kidney cells (293T) and human histiocytic lymphoma cells (U937).

Facile and Novel Eco-Friendly Poly(Vinyl Alcohol) Nanofilters Using the Photocatalytic Property of Titanium Dioxide

This study aimed to develop a highly efficient nanofilter for capturing fine particles using electrostatic forces. Poly(vinyl alcohol) (PVA), a water-soluble synthetic polymer, was selected as the main component of the filter because it can be easily fabricated by electrospinning. Titanium dioxide (TiO₂) nanopowder with an anatase structure was applied to the nanofilters as it has the highest photocatalytic activity among the existing photocatalysts. PVA nanofilters fabricated by electrospinning could still be dissolved in water by hydrolysis. Therefore, heat treatment was performed to make the nanofilters stable, thereby forming C=O bonds by keto-enol tautomerization. Structural changes in the PVA nanofilter before and after heat treatment were investigated by X-ray diffraction (XRD) and Fourier transform infrared (FT-IR) analysis. As the TiO₂ concentration increased, the fiber diameter of the PVA nanofilter decreased and a homogeneous fiber was obtained. The filtration efficiency and pressure drop also improved significantly, compared to those of the PVA-only nanofilter. Moreover, we observed eco-friendly decomposition of the PVA/TiO₂ nanofilter into water and carbon dioxide by a photocatalytic reaction under UV irradiation.

A novel three-dimensional network of CuCr2O4/CuO nanofibers for voltammetric determination of anticancer drug methotrexate

Considering the importance of measuring anticancer drugs, a carbon paste electrode (CPE) modified with CuCr₂O₄/CuO nanofibers in the presence of hydrophobic ionic liquid (IL) was fabricated for methotrexate (MTX) sensing. CuCr₂O₄/CuO nanofibers were prepared by electrospinning method. Then, the morphology and structure of the nanofibers were studied by scanning electron microscopy, thermal analysis, X-ray diffraction, energy-dispersive X-ray, map analysis, and FT-IR spectroscopy. The electrochemical behavior of MTX at CuCr₂O₄/CuO/IL/CPE surface was studied using cyclic voltammetry, differential pulse voltammetry, and electrochemical impedance spectroscopy. After optimization of the experimental parameters, the prepared sensor showed a low detection limit of 25 nM MTX, based on signal-to-noise (S/N = 3), and it can determine in a wide range of 0.1-300 μM in Britton-Robinson buffer solution at pH 2.5. The modified electrode was used to determine MTX concentration in blood and urine samples with good recoveries of 94.1-104.3. This sensor has several advantages such as low cost, easy preparation, high-performance speed and high sensitivity, selectivity, stability, and repeatability. Graphical abstract Scheme of preparation of CuCr₂O₄/CuO nanofibers by electrospinning method and design of a carbon past electrode using prepared nanofibers (CuCr₂O₄/CuO/IL/CPE). This electrode was used for methotrexate determination in plasma and urine samples using differential pulse voltammetry.

Fabrication of tubular braid reinforced PMIA nanofiber membrane with mussel-inspired Ag nanoparticles and its superior performance for the reduction of 4-nitrophenol

A novel tubular braid reinforced (TBR) PMIA/CA-PEI/Ag nanofiber membrane for application in dynamic catalysis was introduced in this study. The preparation method of the TBR PMIA/CA-PEI/Ag nanofiber membrane was facile and efficient. The TBR PMIA/CA-PEI/Ag nanofiber membrane was characterized by field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD) and thermal gravimetric analysis (TGA). The mechanical properties were evaluated by a universal material testing machine. The tensile strength of TBR nanofiber membrane exceeded 500 MPa, whereas that of the nanofiber membrane without reinforcement was merely 10 MPa. Besides, the compressive strength of the TBR nanofiber membrane was also reinforced, which indicated that the TBR nanofiber membrane could withstand a higher operating pressure. The reduction of 4-NP to 4-AP was selected as the model reaction to evaluate the catalytic property of TBR PMIA/CA-PEI/Ag nanofiber membrane. The apparent rate constant of dynamic catalysis was 34.58 times higher than that of static catalysis. After 10 cycles, the conversion of 4-NP was still higher than 95.3%. This indicated that the TBR PMIA/CA-PEI/Ag nanofiber membrane had superior stability and recyclability. Besides, the TBR PMIA/CA-PEI/Ag nanofiber membrane also showed superior catalytic performance when it was used for catalyzing other environmental pollutants.

Deproteinised natural rubber latex grafted poly(dimethylaminoethyl methacrylate) - poly(vinyl alcohol) blend membranes: Synthesis, properties and application

Natural rubber latex was initially deproteinised (DNRL) and then subjected to physicochemical modifications to make high functional membranes for drug delivery applications. Initially, DNRL was prepared by incubating with urea, sodiumdodecylsulphate and acetone followed by centrifugation. The deproteinisation was confirmed by CHN analysis. The DNRL was then chemically modified by grafting (dimethylaminoethyl methacrylate) onto NR particles by using a redox initiator system viz; cumene hydroperoxide/tetraethylenepentamine, followed by dialysis for purification. The grafting was confirmed by dynamic light scattering, Fourier transform infrared spectroscopy and nuclear magnetic resonance spectroscopy. The grafted system was blended with a hydrophilic adhesive polymer PVA and casted into membranes. The membranes after blending showed enhanced mechanical properties with a threshold concentration of PVA. The moisture uptake, swelling and water contact angle experiments indicated an increased hydrophilicity with an increased PVA content in the blend membranes. The grafted DNRL possessed significant antibacterial property which has been found to be retained in the blended form. A notable decrease in cytotoxicity was observed for the modified DNRL membranes than the bare DNRL membranes. The in-vitro drug release studies using rhodamine B as a model drug, confirmed the utility of the prepared membranes to function as a drug delivery matrix.

Fabrication of ascorbyl palmitate loaded poly(caprolactone)/silver nanoparticle embedded poly(vinyl alcohol) hybrid nanofibre mats as active wound dressings via dual-spinneret electrospinning

AP loaded PCL/AgNP embedded PVA hybrid nanofibre mats were prepared through dual-spinneret electrospinning, which altogether contributed to wound healing.

A Sustainable Approach to Fabricating Ag Nanoparticles/PVA Hybrid Nanofiber and Its Catalytic Activity

Ag nanoparticles were synthesized by using Ficus altissimaBlume leaf extract as a reducing agent at room temperature. The resulting Ag nanoparticles/PVA mixture was employed to create Ag nanoparticles/PVA (polyvinyl alcohol) hybrid nanofibers via an electrospinning technique. The obtained nanofibers were confirmed by means of UV-Vis spectroscopy, The X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and then tested to catalyze KBH₄ reduction of methylene blue (MB). The catalytic results demonstrate that the MB can be reduced completely within 15 min. In addition, the Ag nanoparticles/PVA hybrid nanofibers show reusability for three cycles with no obvious losses in degradation ratio of the MB.

Green fabrication of antibacterial polymer/silver nanoparticle nanohybrids by dual-spinneret electrospinning

Nanohybrids from waterborne polyurethane, poly(vinyl alcohol) and silver nanoparticles of ultrasmall sizes (5.1 ± 0.6 nm) are facilely obtained by directly one-step dual-spinneret electrospinning fabrication in water without additional chemicals.