Fabrication of PVA-chitosan-based nanofibers for phytase immobilization to enhance enzymatic activity

Advanced applications in enzyme-induced electrospun nanofibers

Electrospun nanofibers, renowned for their high specific surface area, robust mechanical properties, and versatile chemical functionalities, offer a promising platform for enzyme immobilization. Over the past decade, significant strides have been made in developing enzyme-induced electrospun nanofibers (EIEN). This review systematically summarizes the advanced applications of EIEN which are fabricated using both non-specific immobilization methods including interfacial adsorption (direct adsorption, cross-linking, and covalent binding) and encapsulation, and specific immobilization techniques (coordination and affinity immobilization). Future research should prioritize optimizing immobilization techniques to achieve a balance between enzyme activity, stability, and cost-effectiveness, thereby facilitating the industrialization of EIEN. We elucidate the rationale behind various immobilization methods and their applications, such as wastewater treatment, biosensors, and biomedicine. We aim to provide guidelines for developing suitable EIEN immobilization techniques tailored to specific future applications.

Biofabrication of aminated nanocellulose reinforced polyvinyl alcohol/chitosan nanofibrous scaffold for sustained release of diltiazem hydrochloride

In the modern environment conscious era, there has been a huge demand for the effective green method to fabricate biomaterials for sustained transdermal release of diltiazem hydrochloride to treat hypertension and cardiac failure. In this vein, the present study explores the amination of waste jute sourced nanocellulose (ANC) and its effect as a reinforcing filler to design electrospun polyvinyl alcohol (PVA)/chitosan based polymeric nanofibrous scaffold for drug delivery. The characterization results of FTIR (Fourier Transform Infrared Spectroscopy) confirm the successful chemical modification of nanocellulose (NCC). SEM (Scanning Electron Microscopy) results indicate the morphological modifications in ANC due to grafting. ANC enhances the mechanical properties of scaffold and sustains the release of the loaded drug to 67.89±3.39% as compared to the pure PVA/chitosan scaffold of 92.63±4.63% over a period of 72 h as shown by the results of in-vitro drug release study. Moreover, the incorporation of 0.5 % ANC improves the anti-bacterial activity against both gram-positive (97.4±4.87%, reduction in viable cells count) and gram-negative bacteria (98.5±4.93%, reduction in viable cells count). Further, the skin irritation and MTT assay authenticate the biocompatibility of the developed scaffold. The overall findings hence prove the efficacy of the engineered scaffold as a potential transdermal patch for sustained drug delivery applications.

High-performance, breathable and flame-retardant moist-electric generator based on asymmetrical nanofiber membrane assembly

Moist-electric generators (MEGs), which are capable of spontaneously generating energy from ubiquitous moisture, are considered as a potential power supply candidate for wearable electronics. However, the application of the MEGs in the wearable field is still challenging due to the low electric output and the lack of wearable attributes such as breathability and flame retardancy. Herein, we demonstrated a wearable MEG with high power-output, breathability and flame retardancy, which was fabricated by designing an asymmetrical nanofiber assembly using hydrophilic polyvinyl alcohol/phytic acid (PVA/PA) and hydrophobic polyvinylidene difluoride (PVDF) nanofiber membranes. Owing to the synergistic effects of strong water absorption, enhanced ion release and numerous micro-nano transport channels, a single MEG of 1 cm2 could constantly generate high direct-current (DC) power, i.e., a voltage of 1.0 V, a current of 15.5 μA, and a power density of 3.0 μW cm-2, outperforming other reported nanofiber-based MEGs. More importantly, the asymmetric nanofiber structure ensured the moisture circulation inside MEG and thus produced a sustained voltage output for 7 days without any deterioration. The MEG also showed good flexibility, air/moisture permeability and flame retardancy, which give it necessary wearable attributes. Furthermore, large-scale integration of MEG units could be readily realized to fabricate a power source device for driving different portable electronics, while the moisture sensitivity made the MEG well used for sensing applications (e.g., respiration monitoring, fire warning).

Fabrication and characterization of polyvinyl alcohol-chitosan composite nanofibers for carboxylesterase immobilization to enhance the stability of the enzyme

Electrospinning stands out as a flexible and viable method, presenting designed nanoscale materials with customized properties. This research demonstrates the immobilization of carboxylesterase protein Ha006a, reported for its adequacy in pesticide bioremediation by utilizing the electrospinning strategy. This strategy was utilized to create nanofibers by incorporating variable mixtures of biodegradable and cost-effective polyvinyl alcohol (PVA)-chitosan (CS) nanofiber solution (PVA100, PVA96, PVA94, PVA92 and PVA90). All the mixtures were electrospun at a reliable voltage of 21 kV, maintaining a gap of 12 cm from the nozzle. The Ha006a, sourced from Helicoverpa armigera, was consolidated into the optimized PVA90 polymer mixture. The electrospun nanofibers experienced comprehensive characterization utilizing distinctive microscopy and spectroscopy procedures counting FESEM, TGA, XRD and FTIR. The comparative investigation of the esterase property, ideal parameters and stability of the unbound and bound/immobilized Ha006a was scrutinized. The results uncovered an essential elevation in the ideal conditions of enzyme activity post-immobilization. The PVA-CS control nanofiber and Ha006a-PVA-CS showed a smooth structure, including an average breadth of around 170.5 ± 44.2 and 222.5 ± 66.5 nm, respectively. The enzyme-immobilized nanofibers displayed upgraded stability and comprehensive characterization of the nanofiber, which guaranteed genuineness and reproducibility, contributing to its potential as a potent device for bioremediation applications. This investigation opens the way for the manufacture of pesticide-resistant insect enzyme-based nanofibers, unlocking their potential for assorted applications, counting pesticide remediation and ensuring environmental sustainability.

Formulation and characterization of polyvinyl alcohol/chitosan composite nanofiber co-loaded with silver nanoparticle & luliconazole encapsulated poly lactic-co-glycolic acid nanoparticle for treatment of diabetic foot ulcer

Chronic wounds are prone to fungal infections, possess a significant challenge, and result in substantial mortality. Diabetic wounds infected with Candida strains are extremely common. It can create biofilm at the wound site, which can lead to antibiotic resistance. As a result, developing innovative dressing materials that combat fungal infections while also providing wound healing is a viable strategy to treat infected wounds and address the issue of antibiotic resistance. Present work proposed anti-infective dressing material for the treatment of fungal strains Candida-infected diabetic foot ulcer (DFU). The nanofiber was fabricated using polyvinyl Alcohol/chitosan as hydrogel base and co-loaded with silver nanoparticles (AgNP) and luliconazole-nanoparticles (LZNP) nanoparticles, prepared using PLGA. Fabricated nanofibers had pH close to target area and exhibited hydrophilic surface suitable for adhesion to wound area. The nanofibers showed strong antifungal and antibiofilm properties against different strains of Candida; mainly C. albicans, C. auris, C. krusei, C. parapsilosis and C. tropicalis. Nanofibers exhibited excellent water retention potential and water vapour transmission rate. The nanofibers had sufficient payload capacity towards AgNP and LZNP, and provided controlled release of payload, which was also confirmed by in-vivo imaging. In-vitro studies confirmed the biocompatibility and enhanced proliferation of Human keratinocytes cells (HaCaT). In-vivo studies showed accelerated wound closure by providing ant-infective action, supporting cellular proliferation and improving blood flow, all collectively contributing in expedited wound healing.

Design of a 3D Amino-Functionalized Rice Husk Ash Nano-Silica/Chitosan/Alginate Composite as Support for Laccase Immobilization

Recycling of agro-industrial waste is one of the major issues addressed in recent years aimed at obtaining products with high added value as a future alternative to traditional ones in the per-spective of a bio-based and circular economy. One of the most produced wastes is rice husk and it is particularly interesting because it is very rich in silica, a material with a high intrinsic value. In the present study, a method to extract silica from rice husk ash (RHA) and to use it as a carrier for the immobilization of laccase from Trametes versicolor was developed. The obtained mesoporous nano-silica was characterized by X-ray diffraction (XRD), ATR-FTIR spectroscopy, Scanning Elec-tron Microscopy (SEM), and Energy Dispersive X-ray spectroscopy (EDS). A nano-silica purity of about 100% was found. Nano-silica was then introduced in a cross-linked chitosan/alginate scaffold to make it more easily recoverable after reuse. To favor laccase immobilization into the composite scaffold, functionalization of the nano-silica with (γ-aminopropyl) triethoxysilane (APTES) was performed. The APTES/RHA nano-silica/chitosan/alginate (ARCA) composite al-lowed to obtain under mild conditions (pH 7, room temperature, 1.5 h reaction time) a robust and easily reusable solid biocatalyst with 3.8 U/g of immobilized enzyme which maintained 50% of its activity after six reuses. The biocatalytic system, tested for syringic acid bioremediation, was able to totally oxidize the contaminant in 24 h.

Advances in immobilization of phytases and their application

The review describes the advances in the phytase immobilization for the past decade and their biotechnological applications. Different approaches for phytase immobilization are described including the process using organic and inorganic matrices and microbial cells, as well as nanostructures of various nature. Moreover, the immobilization of phytase-producing microbial cells and the use of cross-linked phytase aggregates have been under consideration. A detailed classification of various carriers for immobilization of phytases and the possibility of their applications are presented. A particular attention is drawn to a breakthrough approach of biotechnological significance to the design of microencapsulation of bacterial phytase from Obesumbacterium proteus in the recombinant extremophile of Yarrowia lipolytica.

A Review of Chitosan and Chitosan Nanofiber: Preparation, Characterization, and Its Potential Applications

Chitosan is produced by deacetylating the abundant natural chitin polymer. It has been employed in a variety of applications due to its unique solubility as well as its chemical and biological properties. In addition to being biodegradable and biocompatible, it also possesses a lot of reactive amino side groups that allow for chemical modification and the creation of a wide range of useful derivatives. The physical and chemical characteristics of chitosan, as well as how it is used in the food, environmental, and medical industries, have all been covered in a number of academic publications. Chitosan offers a wide range of possibilities in environmentally friendly textile processes because of its superior absorption and biological characteristics. Chitosan has the ability to give textile fibers and fabrics antibacterial, antiviral, anti-odor, and other biological functions. One of the most well-known and frequently used methods to create nanofibers is electrospinning. This technique is adaptable and effective for creating continuous nanofibers. In the field of biomaterials, new materials include nanofibers made of chitosan. Numerous medications, including antibiotics, chemotherapeutic agents, proteins, and analgesics for inflammatory pain, have been successfully loaded onto electro-spun nanofibers, according to recent investigations. Chitosan nanofibers have several exceptional qualities that make them ideal for use in important pharmaceutical applications, such as tissue engineering, drug delivery systems, wound dressing, and enzyme immobilization. The preparation of chitosan nanofibers, followed by a discussion of the biocompatibility and degradation of chitosan nanofibers, followed by a description of how to load the drug into the nanofibers, are the first issues highlighted by this review of chitosan nanofibers in drug delivery applications. The main uses of chitosan nanofibers in drug delivery systems will be discussed last.

Composition Effects on the Morphology of PVA/Chitosan Electrospun Nanofibers

Since the SARS-CoV-2 pandemic, the interest in applying nanofibers t air filtration and personal protective equipment has grown significantly. Due to their morphological and structural properties, nanofibers have potential applications for air filtration in masks and air filters. However, most nanofiber membrane materials used for these purposes are generally non-degradable materials, which can contribute to the disposal of plastic waste into the environment. Hence, this work aims to produce polyvinyl alcohol (PVA) and chitosan (CS) biodegradable nanofibers with controlled morphology and structure via electrospinning. An experimental design was used to investigate the effects of the PVA|CS ratio and concentration on the properties of the electrospinning compositions and electrospun nanofiber mat. The electrospinning parameters were constant for all experiments: Voltage of 20 kV, a feed rate of 0.5 mL·h−1, and a distance of 10 cm between the needle and a drum collector. CS proved to be an efficient adjuvant to the PVA’s electrospinning, obtaining a wide range of nanofiber diameters. Furthermore, 6.0% PVA and 1% CS were the best compositions after optimization with the response surface methodology, with a mean fiber diameter of 204 nm. The addition of biocide agents using the optimized condition was also investigated, using surfactants, citric acid, and pure and encapsulated essential oils of Lippia sidoides. Pure oil improved the material without enlarging the nanofiber sizes compared to the other additives. The nanofiber membranes produced have the potential to be used in air filtration or wound-dressing applications where biocidal activity is needed.

Immobilization of Biomass Materials for Removal of Refractory Organic Pollutants from Wastewater

In the field of environmental science and engineering, microorganisms, enzymes and algae are promising biomass materials that can effectively degrade pollutants. However, problems such as poor environmental adaptability, recycling difficulties, and secondary pollution exist in the practical application of non-immobilized biomass materials. Biomass immobilization is a novel environmental remediation technology that can effectively solve these problems. Compared with non-immobilized biomass, immobilized biomass materials have the advantages of reusability and stability in terms of pH, temperature, handling, and storage. Many researchers have studied immobilization technology (i.e., methods, carriers, and biomass types) and its applications for removing refractory organic pollutants. Based on this, this paper reviews biomass immobilization technology, outlines the mechanisms and factors affecting the removal of refractory organic pollutants, and introduces the application of immobilized biomass materials as fillers for reactors in water purification. This review provides some practical references for the preparation and application of immobilized biomass materials and promotes further research and development to expand the application range of this material for water purification.

Evaluation of the Chemical, Morphological, Physical, Mechanical, and Biological Properties of Chitosan/Polyvinyl Alcohol Nanofibrous Scaffolds for Potential Use in Oral Tissue Engineering

Background Chitosan is a biocompatible, biodegradable, and non-toxic natural polymer that can be fabricated by different methods for use in dental and biomedical fields. Electrospinning can produce polymeric nanofibrous scaffolds and membranes with desirable properties for use in tissue engineering. The objectives of this study were to investigate several morphological, physical, and biological characteristics of these nanofibrous scaffolds and evaluate their potential use in tissue engineering. Methodology Chitosan/polyvinyl alcohol nanofibrous scaffolds (CS/PVA NFS) in a ratio of 70/30 were fabricated by conventional electrospinning. The scaffolds were evaluated chemically by Fourier transformed infrared spectroscopy (FTIR) and morphologically by the atomic force microscope (AFM) and the field emission-scanning electron microscope (FE-SEM). These scaffolds were also evaluated mechanically by a tensile strength test and several investigations, including water contact angle, swelling ratio, and degradation ratio. Biological evaluations included protein adsorption, cell culture, and cell viability assay. Results The morphological evaluation revealed a homogenous, bead-free mat with an average fiber diameter of 172.7 ± 56.8 nm, an average pore size of 0.54 ± 0.17 µm, and porosity of 74.8% ± 3.3%; the scaffolds showed a tensile strength of 6.67 ± 0.7 Mpa. Scaffolds showed a desired hydrophilic property, as shown by the water contact angle test with a mean angle of 29.5°, while the swelling ratio was 229%, and degradability in phosphate buffer solution after 30 days was 26.9 ± 2.9%. In-vitro cell culture study with adipose tissue mesenchymal stem cells and cell viability and cytotoxicity tests by MTT assay demonstrated well-attached cells with increasing proliferation rate with no signs of cytotoxicity. Conclusions Assessment of the CS/PVA NFS revealed randomly oriented bead-free and porous mats. The scaffolds were stable at aqueous solutions following thermal treatment. They were hydrophilic, biodegradable, and biocompatible, as shown by the cell culture and MTT assay, which suggest that the fabricated scaffolds have the potential to be used in tissue engineering applications either as scaffolds, bio-grafts, or barrier membranes.

Recent advancements in encapsulation of chitosan-based enzymes and their applications in food industry

Enzymes are readily inactivated in harsh micro-environment due to changes in pH, temperature, and ionic strength. Developing suitable and feasible techniques for stabilizing enzymes in food sector is critical for preventing them from degradation. This review provides an overview on chitosan (CS)-based enzymes encapsulation techniques, enzyme release mechanisms, and their applications in food industry. The challenges and future prospects of CS-based enzymes encapsulation were also discussed. CS-based encapsulation techniques including ionotropic gelation, emulsification, spray drying, layer-by-layer self-assembly, hydrogels, and films have been studied to improve the encapsulation efficacy (EE), heat, acid and base stability of enzymes for their applications in food, agricultural, and medical industries. The smart delivery design, new delivery system development, and in vivo releasing mechanisms of enzymes using CS-based encapsulation techniques have also been evaluated in laboratory level studies. The CS-based encapsulation techniques in commercial products should be further improved for broadening their application fields. In conclusion, CS-based encapsulation techniques may provide a promising approach to improve EE and bioavailability of enzymes applied in food industry.HighlightsEnzymes play a critical role in food industries but susceptible to inactivation.Chitosan-based materials could be used to maintain the enzyme activity.Releasing mechanisms of enzymes from encapsulators were outlined.Applications of encapsulated enzymes in food fields was discussed.

Preparation of Needleless Electrospinning Polyvinyl Alcohol/Water-Soluble Chitosan Nanofibrous Membranes: Antibacterial Property and Filter Efficiency

Electrospinning is an efficient method of producing nanofibers out of polymers that shows a great potential for the filtration territory. Featuring water-soluble chitosan (WS-CS), a low-pollution process and a self-made needleless machine, PVA/WS-CS nanofibrous membranes were prepared and evaluated for nanofiber diameter, bacteriostatic property, filtration efficiency, pressure drop, and quality factor. Test results indicate that the minimal fiber diameter was 216.58 ± 58.15 nm. Regardless of the WS-CS concentration, all of the PVA/WS-CS nanofibrous membranes attained a high porosity and a high water vapor transmission rate (WVTR), with a pore size of 12.06–22.48 nm. Moreover, the membranes also exhibit bacteriostatic efficacy against Staphylococcus aureus, an optimal quality factor of 0.0825 Pa⁻¹, and a filtration efficiency as high as 97.0%, that is 72.5% higher than that of common masks.

Morphological study of electrospun chitosan/poly(vinyl alcohol)/glycerol nanofibres for skin care applications

This study aimed to evaluate the influence of formulation and procedure parameters in obtaining thick and continuous chitosan/PVA/glycerol nanofibres to be applied in skin care. For that, the polymers were characterized by nuclear magnetic resonance, Fourier-transform infrared spectroscopy, and size-exclusion chromatography. After this, 96 chitosan/PVA/glycerol nanofibre scaffolds were prepared by electrospinning method, using factorial designs. The independent variables were crude and pure chitosan, 2 brands of PVA, 2 needle gauges, high and low polymer concentration, high and low glycerol concentration, and final solution with and without ultrafiltration. Morphological analysis was performed by scanning electron microscopy, atomic force microscopy, and confocal microscopy. The best sample (NF67) presented an average thickness of 268.3 nm, uniform distribution, and high yield. It was obtained at a 1:3.5 (crude chitosan: PVA with lower molecular weight, but more hydrolysed) ratio and lower glycerol concentration, suggesting that the degree of hydrolysis of the PVA is more important than its molecular weight for obtaining better quality nanofibres and that the glycerol also makes the electrospinning process difficult. Thus, it was possible to choose parameters that provide scaffolds that could be applied as a matrix extracellular-like material in wound healing.

Immobilized phytases: an overview of different strategies, support material, and their applications in improving food and feed nutrition

Phytases are the most widely used food and feed enzymes, which aid in nutritional improvement by reducing anti-nutritional factor. Despite the benefits, enzymes usage in the industry is restricted by several factors such as their short life-span and poor reusability, which result in high costs for large-scale utilization at commercial scale. Furthermore, under pelleting conditions such as high temperatures, pH, and other factors, the enzyme becomes inactive due to lesser stability. Immobilization of phytases has been suggested as a way to overcome these limitations with improved performance. Matrices used to immobilize phytases include inorganic (Hydroxypatite, zeolite, and silica), organic (Polyacrylamide, epoxy resins, alginate, chitosan, and starch agar), soluble matrix (Polyvinyl alcohol), and nanomaterials including nanoparticles, nanofibers, nanotubes. Several surface analysis methods, including thermal gravimetric analysis (TGA), differential scanning calorimetry (DSC), and FTIR analysis, have been used to characterize immobilized phytase. Immobilized phytases have been used in a broad range of biotechnological applications such as animal feed, biodegradation of food phytates, preparations of myo-inositol phosphates, and sulfoxidation by vanadate-substituted peroxidase. This article provides information on different matrices used for phytase immobilization from the last two decades, including the process of immobilization and support material, surface analysis techniques, and multifarious biotechnological applications of the immobilized phytases.

Electrospinning of Chitosan for Antibacterial Applications—Current Trends

Chitosan is a natural biopolymer that can be suitable for a wide range of applications due to its biocompatibility, rigid structure, and biodegradability. Moreover, it has been proven to have an antibacterial effect against several bacteria strains by incorporating the advantages of the electrospinning technique, with which tailored nanofibrous scaffolds can be produced. A literature search is conducted in this review regarding the antibacterial effectiveness of chitosan-based nanofibers in the filtration, biomedicine, and food protection industries. The results are promising in terms of research into sustainable materials. This review focuses on the electrospinning of chitosan for antibacterial applications and shows current trends in this field. In addition, various aspects such as the parameters affecting the antibacterial properties of chitosan are presented, and the application areas of electrospun chitosan nanofibers in the fields of air and water filtration, food storage, wound treatment, and tissue engineering are discussed in more detail.

Construction of Metal Hydrate-Based Amorphous Magnetic Nanosheets for Enhanced Protein Enrichment and Immobilization

Inspired by the hierarchical fabrication technique, many self-assembly procedures have improved the construction of nanomaterials with unique physicochemical characteristics and multiple functions. The generation of multiple complexes is always accompanied by hierarchical structures and intriguing properties that are distinct from their individual segments. An interesting composite is amorphous magnetic Zn-Zr phosphate hydrated nanosheets (Zn-Zr APHNs), generated using templated synthesis and nanoparticle codeposition. The special porous structure of this construct, together with the abundance of metal ions and hydrate present, endows it with many interaction sites for proteins, provides high loading efficiency, and enhances bioactivity. Then, a series of proteins, including enzymes, was immobilized by the Zn-Zr APHNs by multiple interactions, high ionization, and larger surface of the nanosheets. In this study, novel methods for the enrichment of bioactive proteins while retaining the activity of protein payloads are presented. As a verification method, it is indicated that the Zn-Zr APHNs can deliver enzyme proteins (i.e., Cyt-c) to increase the catalytic activity with their biological function and structural integrity, resulting in a highly increased activity to free proteins.

Improved thermal stability of phytase from Yersinia intermedia by physical adsorption immobilization on amino-multiwalled carbon nanotubes

Phytase is used in poultry diets to hydrolyze and release of phytate-bound phosphorus. Immobilization on nanomaterials optimizes enzyme's thermal stability and reusability. This study aimed to immobilize the recombinant phytase from Yersinia intermedia on the surface of amino-multi-walled carbon nanotubes (amino-MWCNTs) by physical adsorption. For this, zeta potential measurement, FTIR spectroscopic analysis, scanning electron microscope (SEM), kinetic as well as thermodynamic parameters were used to characterize immobilized phytase on amino-MWCNTs. According to results, the optimum temperature of the immobilized phytase increased from 50 to 70 °C and also thermal and pH stability improved considerably. Moreover, immobilization led to an increase in the value of K_m and k_cat from 0.13 to 0.33 mM and 2220 to 2776 s^-1, respectively. In addition, the changes in activation energy of thermal inactivation (ΔE^#_{a (D)}), the free energy of thermal inactivation (ΔG^#_D) and the enthalpy of thermal inactivation (ΔH^#_D) for immobilized phytase increased by +11.05, +24.7 and +11.4 kj/mole, respectively, while the value of the change in the entropy of thermal inactivation (ΔS^#_D) decreased by - 0.04 kj/mole.K. Overall, our results showed that adsorption immobilization of phytase on amino-MWCNTs increases thermal, pH and storage stability as well as some of kinetic parameters.

Chitosan-based nanofibers for enzyme immobilization

The widespread application of soluble enzymes in industrial processes is considered restrict due to instability of enzymes outside optimum operating conditions. For instance, enzyme immobilization can overcome this issue. In fact, chitosan-based nanofibers have outstanding properties, which can improve the efficiency in enzyme immobilization and the stability of enzymes over a wide range of operating conditions. These properties include biodegradability, antimicrobial activity, non-toxicity, presence of functional groups (amino and hydroxyl), large surface area to volume ratio, enhanced porosity and mechanical properties, easy separations and reusability. Therefore, the present review explores the advantages and drawbacks concerning the different methods of enzyme immobilization, including adsorption, cross-linking and entrapment. All these strategies have questions that still need to be addressed, such as elucidation of adsorption mechanism (physisorption or chemisorption); effect of cross-linking reaction on intramolecular and intermolecular interactions and the effect of internal and external diffusional limitations on entrapment of enzymes. Moreover, the current review discusses the challenges and prospects regarding the application of chitosan-based nanofibers in enzyme immobilization, towards maximizing catalytic activity and lifetime.

Propolis loaded and genipin-crosslinked PVA/chitosan membranes; characterization properties and cytocompatibility/genotoxicity response for wound dressing applications

Loading propolis by a simple process using genipin as a crosslinking agent and fabrication of a novel PVA/Chitosan-Propolis membrane scaffolds were reported for wound dressing applications. The research is focused on the effects of propolis on characterization properties of membrane such as chemical structure, surface morphology, degradation ratio, crystallinity, hydrophilicity, water uptake capacity, water vapour transmission rate and mechanical aspect. It was noticed that water uptake capacity and hydrophilicity properties of membrane considerably affected by the propolis. By addition of (0.50, % v/v) propolis, the contact angle of the PVA/Chitosan membrane was remarkably decreased from 86.29° ± 3 to 45 ± 2°. 3-(4,5-dimethylthiazoyl-2-yl)-2,5-diphenylte-trazolium (MTT) bromide test and SEM were used to analyse the cytocompatibility of the membranes and morphology of cells on membrane. The propolis incorporated membrane showed cell proliferation rate 176 ± 13%, 775 ± 1%, and 853 ± 23%, at 24 h, 27 h and 120 h, respectively. SEM images also supported the cell behaviour on membrane. DNA fragmentation was also investigated with genotoxicity test. The studies on the interactions between membranes and MEF cells revealed that the incorporation of propolis into membrane promoted cell proliferation. These overall results presented that propolis incorporated membranes could have potentially appealing application as scaffolds for wound healing applications.