Electrospun Poly Vinyl Alcohol Research Articles

Preparation and photocatalytic and antibacterial properties of polyvinyl alcohol/chitosan/TiO2@Ag electrospun nanofibers

Polyvinyl alcohol (PVA) is a widely used polymer in the electrospinning technique. It is water-soluble, which limits the application of electrospun PVA matrix. In this study, chitosan (CS) and biosynthesized TiO2@Ag nanoparticles were incorporated into PVA to enhance its antibacterial properties and photocatalysis. The PVA/CS/TiO2@Ag nanofiber mat was prepared using the electrospinning method with a voltage of 20 kV, a needle-collector distance of 15 cm, and a flow rate of 0.5 mL.h−1. The concentrations of the PVA and CS solutions were 10% and 2%, respectively. The TiO2@Ag nanoparticles were synthesized using AgNO3 solution, TiO2 nanoparticles as precursors, and Cleistocalyx operculatus leaf extract as a reducing agent. The morphology and structure of the PVA/CS/TiO2@Ag nanofiber mat were analyzed using scanning electron microscopy and infrared spectroscopy. The PVA/CS/TiO2@Ag nanofibers exhibited an average fibril diameter of 116.4 nm. Additionally, the antibacterial activity against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus), as well as the photocatalytic properties of these mats, were assessed. The results indicated that the addition of CS and TiO2@Ag led to changes in the hydrophilic properties and antibacterial efficacy of PVA. The inhibition zones of the PVA/CS/TiO2@Ag nanofiber mat against E. coli and S. aureus were measured at 5 and 4 mm, respectively. The water contact angle of PVA/CS/TiO2@Ag nanofiber mat showed a significant increase. The PVA/CS/TiO2@Ag nanofibers were able to degrade 94.56 ± 0.57% and 98.17 ± 0.11% of methylene blue dye under sunlight irradiation after 10 and 20 min of exposure, respectively. These findings suggest that the PVA/CS/TiO2@Ag nanofiber mat has the potential for applications in the textile industry or medicinal field as antibacterial and photocatalytic coatings.

Controlled Release of Lysozyme Using Polyvinyl Alcohol-Based Polymeric Nanofibers Generated by Electrospinning.

Polymeric nanofibers generated via electrospinning offer a promising platform for drug delivery systems. This study examines the application of electrospun polyvinyl alcohol (PVA) nanofibers for controlled lysozyme (LZM) delivery. By using various PVA grades, such as the degree of polymerization/hydrolysis, this study investigates their influence on nanofiber morphology and drug-release characteristics. LZM-loaded PVA monolithic nanofibers having 50% drug content exhibit efficient entrapment, wherein rapid dissolution is achieved within 30 min. The initial burst of LZM from the nanofiber was reduced as the LZM content was lowered. The initial dissolution is greatly influenced by the choice of PVA grade used; fully hydrolyzed PVA nanofibers demonstrate controlled release due to the reduced water solubility of PVA. Furthermore, coaxial electrospinning, which creates core-shell nanofibers with polycaprolactone as a controlled release layer, enables sustained LZM release over an extended period. This study confirms a correlation between PVA characteristics and controlled drug release and provides valuable insights into tailoring nanofiber properties for pharmaceutical applications.

Immobilization of natural extract from Humulus lupulus L. in electrospun polyvinyl alcohol nanofibrous membrane for colorimetric determination of ferric

Metallochromic nanofibrous membranes were electrospun from an aqueous solution of xanthohumol (XNS) of Humulus lupulus L. (common hop) extract and polyvinyl alcohol (PVA) for determination of ferric ions. In order to detect ferric ions in aquatic media, a simple, portable, quick, and colorimetric detector was prepared using xanthohumol chromophore as an active spectroscopic detection site encapsulated in PVA nanofibers as a hosting bulk. The CIE Lab color parameters show that binding these poisonous ferric cations to the xanthohumol active detection sites results in a noticeable color shift from yellow (467 nm) to off-white (337 nm). This could be attributed to the creation of a coordination bonds between Fe(III) and phenolic xanthohumol. Increasing the quantity of ferric ions was shown to have a linear effect on the monitored color. The xanthohumol extraction was investigated by High Performance Liquid Chromatography (HPLC). Energy-dispersive X-ray spectrometer (EDX) and scanning electron microscopy (SEM) were employed to characterize the surface morphologies and structural properties of XNS@PVA nanofibers. Electrospun XNS@PVA nanofibrous film with a nanofiber diameter of 75–225 nm was produced. In order to prepare water-insoluble nanofibers, they were exposed to cross-linking with glutaraldehyde fumes. The xanthohumol-containing nanofibers exhibit remarkable ease of use with a detection limit of 0.1–300 ppm. XNS@PVA exhibited high selectivity when compared to various transition metal ions, such as K+, Na+, Ba2+, Zn2+, Cd2+, Hg2+, Co2+, Mn2+, Cu2+, Mg2+, Ni2+, Ca2+, Al3+, and Cr3+. The optimized pH conditions for the detection of Fe(III) were shown to exist between the values of 5 and 7.75. When compared to alternative detection methods, the current assay has the advantages of rapidity, simplicity, cheapness, environmental safety, and ease of operation.

2D and 3D PVA electrospun scaffold evaluation for ligament implant replacement: A mechanical testing, modelling and experimental biomechanics approach

The gold standard to characterise anterior cruciate ligament (ACL) implants is through the evaluation of mechanical properties such as Young's modulus or ultimate tensile stress. Currently, no studies have been performed to relate the in-vivo hyper-elastic behaviour of the ACL with the design of tissue engineered ligaments. The aim of this work is to determine the most comparable 2D/3D polyvinyl alcohol (PVA) electrospun structure to the in-vivo mechanical behaviour of the natural ligament. Biomechanics of 12 young participants were captured while daily and high impact activities were performed. A musculoskeletal knee model and kinematic data were used to estimate the in-vivo ACL length and strain. The in-vivo ACL tensile forces were determined with a non-linear force/strain relationship. 2D scaffolds, 1 twisted filament scaffolds, 3 twisted filaments scaffolds and 3 twisted/braided filaments scaffolds were fabricated using electrospinning and characterised morphologically and mechanically using scanning electron microscopy and tensile testing respectively. Cyclic tensile and shear tests were performed in dry and wet conditions to crosslinked and non-crosslinked samples. The hyper-elastic behaviour of our PVA scaffolds was characterised with the Mooney Rivlin model and a non-linear string-based model, and both models compared with the in-vivo mechanical behaviour of the native ACL. Crosslinked 3 twisted/braided filaments scaffolds faithfully mimicked the morphology and the hyper-elastic behaviour of the natural ACL, showed a good resistance to shear loading and remained undegraded in phosphate-buffer saline solution. This study demonstrated, for the first time, that 3 twisted/braided filaments PVA electrospun scaffolds have an excellent potential for ACL replacements.

Poly (vinyl alcohol) based carbon nanofibers as freestanding anodes for lithium‐ion batteries

AbstractIn this study, we investigated the iodination process for the preparation of water‐soluble polyvinyl alcohol (PVA)‐based carbon nanofibers (CNFs) and their electrochemical properties. Iodinated nanofibers were carbonized at different temperatures (600°C, 800°C) under an argon (Ar) atmosphere. Morphology and physical properties of fiber mats were characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, and thermogravimetric analysis (TGA), while electrical conductivity measurements were done using four probes. As a freestanding anode in half‐cell lithium batteries, the CNFs were prepared by electrospinning of PVA and PVA–CNT blend, which was exposed to iodine vapor at various temperatures (60, 80, and 100°C). Iodine vapor treatment at 80°C and subsequent carbonization at 800°C provided a 29% carbon yield. The resulting CNT‐containing optimized CNFs exhibited superior flexibility, electrical conductivity (2.16 S/cm), and handleability, making them a promising, binder‐free environmentally friendly carbon source for lithium‐ion batteries with high capacity (672 mAh/g at 50 mA/g). The study clearly showed that PVA might be an alternative precursor for the production of carbon micro‐ and nanofibers.Highlights Anodic performance of PVA‐based carbon nanofibers was analyzed. PVA precursor offers economic and environmental option for binder‐free electrodes. PVA–CNT composite nanofibers with optimized iodination and carbonization time identified as a promising high carbon yield carbon source for lithium‐ion batteries. CNT‐containing optimized carbon nanofibers exhibited superior flexibility and electrical conductivity (2.16 S/cm). Freestanding fiber anodes exhibited a higher capacity of 672 mAh/g, at 50 mA/g compared to conventional graphite anode (372 mAh/g).

Nicotine-Loaded Polyvinyl Alcohol Electrospun Nanofibers as Transdermal Patches for Smoking Cessation: Formulation and Characterization

Nicotine-Loaded Polyvinyl Alcohol Electrospun Nanofibers as Transdermal Patches for Smoking Cessation: Formulation and Characterization

Preparation and characterization of glutathione loaded polyvinyl alcohol electrospun nanofibers

Reduced glutathione, or L-glutathione, is a tripeptide protein that occurs naturally in almost all cells of the human body. It is an antioxidant and plays a significant role in neutralizing oxidative stress. Oxidative stress is responsible for promoting many diseases and abnormalities in the body. This antioxidant decreases with time, and resulting in a number of disorders. To overcome these issues, experts recommend taking glutathione supplements. This study was aimed to design glutathione-loaded polyvinyl alcohol nanofibers, considering the properties of nanofibers that could be used as glutathione supplements to improve the deficiency of glutathione in the human body. With the electrospinning technique, poly (vinyl alcohol) loaded glutathione nanofibers were designed. The prepared nanofibers were characterized using Scanning Electron Microscopy (SEM), Fourier Transform Infrared Spectroscopy (FTIR), X-ray diffraction (XRD), and Ultraviolet-Visible Spectroscopy (UV–Vis) techniques. The antioxidant activity of the nanofibers was also determined; the activity indicated the eradication of free radicals.

Multivitamin complex-loaded electrospun polyvinyl alcohol core/shell structure fibers for transdermal delivery system: In-silico and experimental studies

Transdermal delivery systems offer a controlled and targeted environment for releasing drugs compared to other delivery systems. This study presents the fabrication of polyvinyl alcohol (PVA) fibers with a multivitamin complex (MV) using the electrospinning technique (ES). The research focuses on understanding how various fiber structures, such as core/shell, simple fibers, and ES parameters, affect the MC release mechanism and cell viability behavior.The vitamin complexes were uniformly encapsulated within the polymeric chains in all structure fibers. PVA simple fibers with and without the vitamin complex don't significantly differ in diameter size. However, the core/Shell fiber has a notable decrease in fiber diameter of 45 %.The fiber with a core/shell structure resulted in a slower release rate of the vitamin complex than simple fiber. According to the Korsmeyer-Peppas model, the release mechanism observed in our study for the simple fibers is classical Fickian diffusion. Instead, core/shell fibers indicate a more anomalous or non-Fickian behavior.The structural configurations of the fibers do not result in statistically significant differences in cell viability. This could be attributed to the identical nature of materials used, including the polymer and MV, across all cases.Finally, a computational chemistry study was used to examine the interaction between polyvinyl alcohol (PVA) and vitamins K3 and B3, like a model of MV. The analysis showed four strong hydrogen bonds between PVA and vitamin B3, whereas the interaction between PVA and vitamin K3 only had one hydrogen bond. Furthermore, the PVA and vitamin B3 interaction had higher energy and was more exothermic and spontaneous than the PVA-vitamin K3 interaction. On the other hand, the PVA-vitamin K4 interaction displayed higher reactivity due to its lower separation energy. In contrast, the PVA-vitamin B3 interaction was more stable.

Exploring Functionalized Magnetic Hydrogel Polyvinyl Alcohol and Chitosan Electrospun Nanofibers.

Nanofibrous materials present interesting characteristics, such as higher area/mass ratio and reactivity. These properties have been exploited in different applications, such as drug-controlled release and site-specific targeting of biomolecules for several disease treatments, including cancer. The main goal of this study was to develop magnetized nanofiber systems of lysozyme (Lys) for biological applications. The system envisaged electrospun polyvinyl alcohol (PVA) and PVA/chitosan (CS) nanofibers, loaded with Lys, crosslinked with boronic acids [phenylboronic acid (PBA), including 2-acetylphenylboronic acid (aPBA), 2-formylphenylboronic (fPBA), or bortezomib (BTZ)] and functionalized with magnetic nanobeads (IONPs), which was successfully built and tested using a microscale approach. Evaluation of the morphology of nanofibers, obtained by electrospinning, was carried out using SEM. The biological activities of the Lys-loaded PVA/CS (90:10 and 70:30) nanofibers were evaluated using the Micrococcus lysodeikticus method. To evaluate the success of the encapsulation process, the ratio of adsorbed Lys on the nanofibers, Lys activity, and in vitro Lys release were determined in buffer solution at pH values mimicking the environment of cancer cells. The viability of Caco-2 cancer cells was evaluated after being in contact with electrospun PVA + Lys and PVA/CS + Lys nanofibers, with or without boronic acid functionalation, and all were magnetized with IONPs.

Polyvinyl alcohol electrospun nanofiber membrane based solid-phase extraction for monitoring administered aminoglycoside antibiotics in various animal-derived foods.

This work aims to develop a widely applicable method to monitor administered AGs in various animal-derived food samples to ensure food safety. A polyvinyl alcohol electrospun nanofiber membrane (PVA NFsM) was synthesized and employed as solid-phase extraction (SPE) sorbent, in combination with UPLC-MS/MS, for the simultaneous detection of ten AGs in nine types of animal-derived food samples. PVA NFsM exhibited excellent adsorption performance for the targets (with an adsorption rate of over 91.09%), good matrix purification ability (with a reduction of 7.65%-77.47% in matrix effect after SPE), and good recyclability (can be reused 8 times). The method displayed a linear range of 0.1-25000μg/kg and attained limits of detection for AGs were 0.03-15μg/kg. Spiked samples demonstrated a recovery of 91.72%-100.04% with a precision of<13.66%. The practicality of the developed method was verified by testing multiple actual samples.

Electrospun PVA Nanofibers Loaded with Antimicrobial Herbal Extracts for Healing the Infectious Wound

Background: Low-cost, soluble polyvinyl alcohol (PVA) polymers enhance the efficacy of herbal formulations with established antimicrobial properties. Objectives: This study investigates the healing process of Staphylococcus aureus (S. aureus)-infected wounds using PVA loaded with herbal extracts, including Arnebia euchroma, Allium sativum, and Echinacea purpurea. Methods: minimal bactericidal concentration (MBC) and minimal inhibitory concentration (MIC) assays, Disk Diffusion Method (DDM) tests, and Gas Chromatography-Mass Spectrometry (GC/MS) analyses were conducted on herbal extract samples. Twelve male Wistar rats were divided into G1: Negative control group (healthy mice), G2: Wound model + S. aureus (Positive control), G3: wound model + S. aureus + Povidone-iodine, and G4: Wound model + S. aureus + PVA/formulation. Hematoxylin-eosin and immunofluorescent staining were employed to assess wound healing. Results: The ethanolic herbal extract exhibited potent antibacterial activity against S. aureus, with MIC and MBC values in the 1.87 mg/mL range. The PVA/formulation displayed a zone of inhibition with a diameter of 7 mm against S. aureus. Histopathological investigations indicated that the infected wound treated with Nanofibers extract experienced a significant reduction in inflammation between days 7 and 14. Notably, the increased CD3 expression at this site was remarkable for the healing process. Conclusions: Consequently, this experimental study suggests combining PVA and herbal extracts enhances antibacterial properties and promotes CD3 expression and re-epithelialization effects.

Crosslinked PVA/Citric Acid Nanofibrous Separators with Enhanced Mechanical and Thermal Properties for Lithium-Ion Batteries

Electrospinning polyvinyl alcohol (PVA) nanofibrous membranes have gained increased attention for their uses as separators for lithium-ion batteries (LIBs) due to their high porosity and excellent electrolyte wettability, but their poor mechanical and thermal properties have limited their further development. In this work, a crosslinked PVA composite separator (PVA/CA-H) was first prepared via the electrospinning of the PVA and citric acid (CA) mixed solution and then the heating of the nanofibrous membrane, and the effects of the amount of CA on the structure and performance of the PVA/CA-H separator were investigated. The hydroxyl group of PVA and the carboxyl group of CA were crosslinked under the heat treatment, resulting in a slight reduction in the porosity and pore size of the composite separator compared to pure PVA, and to compensate for this issue, the mechanical strengths, as well as the thermal dimensional stability of the PVA/CA-H separator, were significantly improved. Meanwhile, the PVA/CA-H separator exhibited good electrolyte uptake (158.1%) and high ionic conductivity (1.63 mS cm−1), and, thus, the battery assembled with the PVA/CA-H separator exhibited a capacity retention of 96.3% after 150 cycles at 1 C. These features mean that the crosslinked PVA composite separator can be considered as a prospective high-safety and high-performance separator for LIBs.

Bipolymer nanofibers: Engineering nanoscale interface via bubble electrospinning

AbstractModern applications in biomedicine, drug delivery, and tissue engineering demand versatile materials capable of meeting multifaceted requirements. Conventional mono‐functional materials fall short of addressing these complex demands. To tackle this challenge, this study introduces an innovative approach utilizing bubble electrospinning for the fabrication of bipolymeric side‐by‐side nanofibers. These nanofibers incorporate distinct hydrophilic and hydrophobic domains aligned parallel to their axis, achieved through the electrospinning of polyvinyl alcohol (PVA) as the hydrophilic component, alongside either poly(ε‐caprolactone) (PCL) or Nylon6 as the hydrophobic component. The optimal diameter of the bubble electrospinning reservoir was theoretically determined via simulation of electric field using Maxwell 3D software and experimentally validated. Successful electrospinning resulted in nanofibers with hydrophilic and hydrophobic domains derived from PVA/Nylon6 and PVA/PCL polymer combinations. This innovative process yielded nanofibers with diameters as fine as 101 nm in the PVA/Nylon6 bipolymeric nanofibers. Transmission electron microscopy images provide compelling insights into the distinct interfaces formed during polymer‐polymer interactions within the nanofibers, manifesting the Janus structure. Furthermore, Fourier‐transform infrared spectroscopy confirms the presence of both polymers within the nanofiber matrix. This research represents a significant advancement in the efficient production of bipolymer nanofibers, holding promise for a wide range of applications.

Green surface modification of polyvinyl alcohol fibers and its application for dye removal using Doehlert experimental design

The use of eco-friendly techniques and green reagents to modify the properties of synthetic biopolymers is attracting an increasing attention. In this work, L-cysteine (CYS) modified polyvinyl alcohol electrospun fibers (PVA-CYS) were prepared using an easy, fast, and green technique. The incorporation of CYS as a source of nitrogen and sulfur shows an important enhancement in dye removal efficiency compared to polyvinyl alcohol fibers (PVA). The successful grafting of CYS on PVA was proved by FTIR, elemental analysis, SEM, AFM and TGA analysis. Doehlert experimental design was used to optimize the adsorption process of crystal violet (CV) on PVA and PVA-CYS. The two models show good correlations between experimental and predicted responses, with coefficients of determination equal to 0.946 and 0.976, for PVA and PVA-CYS, respectively. The most influencing parameter was the pH for CV removal by adsorption on PVA. However, this parameter affects less the dye removal using PVA-CYS. The modified fibers exhibit excellent adsorption ability toward CV, and the maximum adsorption capacity reaches 197 mg g−1 at neutral pH. An application of this process on a doped real wastewater demonstrates its efficacity and selectivity with a percentage of removal up to 85%.

Electrospun PVA Fibers for Drug Delivery: A Review.

Innovation in biomedical science is always a field of interest for researchers. Drug delivery, being one of the key areas of biomedical science, has gained considerable significance. The utilization of simple yet effective techniques such as electrospinning has undergone significant development in the field of drug delivery. Various polymers such as PEG (polyethylene glycol), PLGA (Poly(lactic-co-glycolic acid)), PLA(Polylactic acid), and PCA (poly(methacrylate citric acid)) have been utilized to prepare electrospinning-based drug delivery systems (DDSs). Polyvinyl alcohol (PVA) has recently gained attention because of its biocompatibility, biodegradability, non-toxicity, and ideal mechanical properties as these are the key factors in developing DDSs. Moreover, it has shown promising results in developing DDSs individually and when combined with natural and synthetic polymers such as chitosan and polycaprolactone (PCL). Considering the outstanding properties of PVA, the aim of this review paper was therefore to summarize these recent advances by highlighting the potential of electrospun PVA for drug delivery systems.

Preparation of electrospun PVA@Ls@BAC@PDMS composite nanofibrous air filtration membrane with high efficiency removal for PM2.5 and excellent heat resistance

AbstractDevelopment of water‐soluble polymer air filtration materials attracts considerable attentions due to their environmentally friendly performance and high efficiency, but the balance of mechanical strength, efficiency and pressure drop still is a severe challenge. Focusing on this issue, polyvinyl alcohol (PVA), bamboo activated carbon (BAC) and sodium lignosulfonate (Ls) were combined to construct an electrospinning system with two filtration functions. In the PVA@Ls@BAC system, the 3D network constructed by the electrospun PVA based nanofibrous could effectively intercept PM2.5, and the introduced Ls enhanced the mechanical strength of PVA nanofibrous due to its good rigidity. In addition, the added negatively charged BAC facilitated the electrostatic adsorption of PM2.5 while also improved the heat resistance of the system. Moreover, polydimethylsiloxane (PDMS) was introduced to enhance the water resistance of the system. The resulting electrospun PVA@Ls@BAC@PDMS composite nanofibrous air filtration membrane exhibited excellent air filtration performance (98.67%), water repellency (123.7° of WCA), and reusable performance, as well as having good mechanical property and the tensile fracture strain reaching 112%. Because of its good performance and simple preparation process, the electrospun PVA@Ls@BAC@PDMS composite nanofibrous air filtration membrane has great application space.

Efficient adsorptive removal of aminoglycoside antibiotics from environmental water

Aminoglycoside antibiotics (AGs) in environmental water are emerging pollutants that must be removed to protect human health and the ecosystem. However, removing AGs from environmental water remains a technical challenge due to high polarity, stronger hydrophilicity and unique characteristics of polycation. Herein, a thermal-crosslinked polyvinyl alcohol electrospun nanofiber membrane (T-PVA NFsM) is synthesized and firstly leveraged as the adsorptive removal of AGs from environmental water. The thermal crosslinking strategy is demonstrated to enhance both the water resistance and hydrophilicity of T-PVA NFsM, thereby effectively interacting with AGs with high stability. Experimental characterizations and analog calculations indicate that T-PVA NFsM utilizes multiple adsorption mechanisms, including electrostatic and hydrogen bonding interactions with AGs. As a result, the material achieves 91.09%–100% adsorption efficiencies and a maximum adsorption capacity of 110.35 mg g−1 in less than 30 min. Furthermore, the adsorption kinetics follow the pseudo-second-order model. After eight consecutive adsorption-desorption cycles, T-PVA NFsM with a simplified recycling process maintains a sustainable adsorption capability. Compared with other forms of adsorption materials, T-PVA NFsM has significant advantages such as less consumption of adsorbent, high adsorption efficiency and fast removal speed. Therefore, T-PVA NFsM-based adsorptive removal holds promise for eliminating AGs from environmental water.

Morphological and Wettability Evaluation of Electrospun Polivinyl Alcohol (PVA) Nanofiber Membrane for Wound Dressing Application

Many researches have focused on producing electrospun nanofiber membranes (ENMs) aiming to speed up physiological events of wound healing. However, it is still a challenge to fabricate functional ENMs using electrospinning technique, taken into account various factors that may affect the fibers diameter such as polymer solution properties, electrospinning parameters and ambient conditions. This study aimed to evaluate the combined electrospinning process parameters and characterize the morphology and wettability of the electrospun polyvinyl alcohol (PVA) nanofiber membranes produced. Process parameters that were optimized include applied voltage, flow rate, and distance to collector. The fabrication of PVA nanofiber membranes was done at 21 kV, 2 mL/h and 10 cm after optimization. Surface morphology and fiber diameter were analyzed using a scanning electron microscope (SEM). The water contact angle was used to analyze wettability. Electrospun PVA nanofiber membranes showed continuous random fiber, no bead defect, hydrophilic surface and average fiber diameters between 265 ± 86 nm and 281 ± 90 nm. Smaller fiber diameter between 200-700 nm can enhance cell migration. It is suggested from this study that the optimized parameters have successfully produced electrospun PVA nanofiber membranes with suitable fiber diameter for cell migration and can direct cell response, thus can be applied as a wound dressing material.

Carbonic Anhydrase-Embedded ZIF-8 Electrospun PVA Fibers as an Excellent Biocatalyst Candidate.

There is a growing concern that the increasing concentration of CO2 in the atmosphere contributes to a potential negative impact on global climate change. To deal with this problem, developing a set of innovative, practical technologies is essential. In the present study, maximizing the CO2 utilization and precipitation as CaCO3 was evaluated. In this manner, bovine carbonic anhydrase (BCA) was embedded into the microporous zeolite imidazolate framework, ZIF-8, via physical absorption and encapsulation. Running as crystal seeds, these nanocomposites (enzyme-embedded MOFs) were in situ grown on the cross-linked electrospun polyvinyl alcohol (CPVA). The prepared composites displayed much higher stability against denaturants, high temperatures, and acidic media than free BCA, and BCA immobilized into or on ZIF-8. During 37 days of storage period study, BCA@ZIF-8/CPVA and BCA/ZIF-8/CPVA maintained more than 99 and 75% of their initial activity, respectively. The composition of BCA@ZIF-8 and BCA/ZIF-8 with CPVA improved stability for consecutive usage in recovery reactions, recycling easiness, and greater control over the catalytic process. The amounts of calcium carbonate obtained by one mg each of fresh BCA@ZIF-8/CPVA and BCA/ZIF-8/CPVA were 55.45 and 49.15 mg, respectively. The precipitated calcium carbonate by BCA@ZIF-8/CPVA reached 64.8% of the initial run, while this amount was 43.6% for BCA/ZIF-8/CPVA after eight cycles. These results indicated that the BCA@ZIF-8/CPVA and BCA/ZIF-8/CPVA fibers could be efficiently applied to CO2 sequestration.

PVA electrospun fibers coated with PPy nanoparticles for wearable strain sensors.

Current conductive polymers win wide applications in smart strain/stress sensors, bioinspired actuators, and wearable electronics. This paper investigates a novel strain sensor by using conductive polypyrrole (PPy) nanoparticles coated polyvinyl alcohol (PVA) fibers as matrix. The flexible, water-resistant PVA fibers are initially prepared by combined electrospinning and annealing techniques, and then are coated with PPy nanoparticles through in situ polymerization. The resultant PPy@PVA fibers exhibit stable, favorable electrical conductivities due to the uniform point-to-point connections among PPy nanoparticles, e.g. after three-time' polymerizations, the PPy@PVA3 fiber film presents a sheet resistance of ∼840 Ω/sq and a bulk conductivity of ∼32.1 mS/cm. Cyclic sensing tests reveal that, PPy@PVA sensors show linear relationships between the relative resistance variations and the applied strains, e.g. the linear deviation of PPy@PVA3 is only 0.9 % within 33 % strain. After long-term stretching/releasing cycles, the PPy@PVA sensor exhibits stable, durable, and reversible sensing behaviors, no evident "drift" is observed over 1,000 cycles (5,000 seconds). This article is protected by copyright. All rights reserved.