Electrospinning of chitosan/PVA nanofibrous membrane at ultralow solvent concentration

Preparation and characterization of PVA/chitosan nanofibers loaded with Dragon's blood or poly helixan as wound dressings

Nanofibers have been investigated in regenerative medicine. Dragon's blood (DB)- and poly helixan PF (PHPF) are natural materials used in cosmetics. Herein, we generated DB- and PHPF-loaded polyvinyl alcohol/chitosan (PVA/CS/DB and PVA/CS/PHPF, respectively) nanofibers. PVA/CS/DB and PVA/CS/PHPF nanofibers had an average diameter of 547.5 ± 17.13 and 521 ± 24.67 nm, respectively as assessed by SEM, and a degradation rate of 43.1 and 47.6 % after 14 days, respectively. PVA/CS/DB and PVA/CS/PHPF nanofibers had a hemolysis rate of 0.10 and 0.39 %, respectively, and a water vapor transmission rate of ∼2200 g.m-2.day-1. These nanofibers exhibited favorable antimicrobial activity against Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, and Bacillus subtilis in vitro. PVA/CS/DB and PVA/CS/PHPF nanofibers demonstrated a sustained release of 77.91 and 76.55 % over 72 h. PVA/CS/DB and PVA/CS/PHPF nanofibers had a high rate of cytocompatibility and significantly improved the viability of NIH/3T3 cells as compared with free drugs or unloaded nanofibers. Histological inspection via H&E and Verhoeff's staining demonstrated PVA/CS/DB and PVA/CS/PHPF nanofibers enhanced the wound healing and damaged tissue recovery of unsplinted wound models by promoting epithelial layer formation, collagen deposition, and enhancing the presence of fibroblasts. Conclusively, PVA/CS/DB and PVA/CS/PHPF can be introduced as potential wound dressing candidates with favorable properties.

Fabrication and characterization of 3-dimensional electrospun poly(vinyl alcohol)/keratin/chitosan nanofibrous scaffold

Layer-by-layer three-dimensional nanofibrous scaffolds (3DENS) were produced using the electrospinning technique. Interest in using biopolymers and application of electrospinning fabrication techniques to construct nanofibers for biomedical application has led to the development of scaffolds composed of PVA, keratin, and chitosan. To date, PVA/keratin blended nanofibers and PVA/chitosan blended nanofibers have been fabricated and studied for biomedical applications. Electrospun scaffolds comprised of keratin and chitosan have not yet been reported in published literature, thus a novel nanofibrous PVA/keratin/chitosan scaffold was fabricated by electrospinning. The resulting 3DENS were characterized using fourier transform infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM), differential scanning colorimetry (DSC), and thermogravimetric analysis (TGA). Physiochemical properties of the polymer solutions such as viscosity (rheology) and conductivity were also investigated. The 3DENS possess a relatively uniform fibrous structure, suitable porosity, swelling properties, and degradation which are affected by the mass ratio of keratin, and chitosan to PVA. These results demonstrate that PVA/keratin/chitosan 3DENS have the potential for biomedical applications.

Fibrous Polymer-Based Composites Obtained by Electrospinning for Bone Tissue Engineering

Currently, the significantly developing fields of tissue engineering related to the fabrication of polymer-based materials that possess microenvironments suitable to provide cell attachment and promote cell differentiation and proliferation involve various materials and approaches. Biomimicking approach in tissue engineering is aimed at the development of a highly biocompatible and bioactive material that would most accurately imitate the structural features of the native extracellular matrix consisting of specially arranged fibrous constructions. For this reason, the present research is devoted to the discussion of promising fibrous materials for bone tissue regeneration obtained by electrospinning techniques. In this brief review, we focus on the recently presented natural and synthetic polymers, as well as their combinations with each other and with bioactive inorganic incorporations in order to form composite electrospun scaffolds. The application of several electrospinning techniques in relation to a number of polymers is touched upon. Additionally, the efficiency of nanofibrous composite materials intended for use in bone tissue engineering is discussed based on biological activity and physiochemical characteristics.

Electrospinning of chitosan-based nanofibers: from design to prospective applications

Chitosan is a biopolymer originating from renewable resources, with great properties which make it an attractive candidate for plenty of applications of contemporary interest. By manufacturing chitosan into nanofibers using the electrospinning method, its potential is amplified due to the enhancement of the active surface and the low preparation cost. Many attempts were made with the aim of preparing chitosan-based nanofibers with controlled morphology targeting their use for tissue engineering, wound healing, food packaging, drug delivery, air and water purification filters. This was a challenging task, which resulted in a high amount of data, sometimes with apparent contradictory results. In this light, the goal of the paper is to present the main routes reported in the literature for chitosan electrospinning, stressing the advantages and disadvantages of each of them. Special emphasis is placed on the influence of various electrospinning parameters on the morphological characteristics of the fibers and their suitability for distinct applications.

Cytotoxicity and hemostatic activity of chitosan/carrageenan composite wound healing dressing for traumatic hemorrhage

Hemorrhage remains a big threat to trauma patients, especially in combat fields. Therefore, we formulated a biocompatible and biopolymer based chitosan/carrageenan composite dressing. This dressing was fabricated using freeze-drying that will serve as a promising material to promote hemostasis and tissue growth required during hemorrhage. The efficacy of dressing was evaluated for its physiochemical analysis, surface morphology, and biodegradability. Further, human dermal fibroblast cells were seeded on dressing and demonstrated non-toxic effects on the cells by showing enhanced cell attachment and proliferation. In vitro hemostatic properties of the dressing were analyzed by human Thrombin-Antithrombin assay. The dressing formed showed steady blood coagulation implying red blood cells and platelet adhesion that helped in thrombin formation, which is responsible for enhancing wound healing. Thus, it is concluded that the composite dressing can be a potent combination to accelerate hemostatic activity against hemorrhage and promote tissue growth for effective wound healing.

Preparation, characterization and kinetics study of chitosan/PVA electrospun nanofiber membranes for the adsorption of dye from water

In this study, chitosan (CS) nanofibers with two different degrees of deacetylation (DDA) were first successfully fabricated from its solution in 1% aqueous acetic acid solution by mixing with poly(vinyl alcohol) (PVA) solution at a weight ratio of 50/50 via the electrospinning method. Then, the CS/PVA membranes were further modified by glutaraldehyde vapor. The prepared nanofibers were characterized by field electron scanning electron microscopy (FESEM), Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), thermogravimetric analysis (TGA), the tensile test, the contact angle test, the weight loss test and the adsorption test for Congo red (CR). SEM analysis showed defect-free nanofibers and a uniform diameter distribution, with an average diameter of 100–125 nm. Subsequently, FTIR spectroscopy, XRD and TGA indicated that the modified CS/PVA membranes had a relatively higher thermal stability, because the thermal decomposition temperature of the unmodified CS/PVA membranes (~250°C) increased to a higher temperature (~ 300°C) for the modified CS/PVA. The nanofiber membranes after modification possessed better mechanical tensile properties. The membranes with lower DDA had a relatively higher tensile strength, which can withstand the maximum tensile strength of up to 6.36 MPa. Furthermore, the resulting membranes showed excellent hydrophilicity and kept their stability in distilled water, acidic, and basic media for 20 days. In the adsorption study, the maximum adsorption capacity of the membrane for CR was 358 mg/l in the optimum operating conditions of 25°C, pH = 6, 0.3 g membrane and 50 ml of 100 mg/l CR solutions. The resulting nanofibers membranes showed a better fitting to the Langmuir isotherm model and pseudo-second-order kinetic model.

Hemostasis and anti-necrotic activity of wound-healing dressing containing chitosan nanoparticles

Necrotic tissues are the dead tissues present in the wounded areas, which need to be removed for rapid wound healing. Various biopolymer-based dressings have been exploited to heal infected wounds, but with limited success. In a quest to develop an effective and economic wound dressing, a biodegradable dressing containing chitosan nanoparticles has been successfully developed. Chitosan nanoparticles were prepared by ionic gelation method and then assembled into the porous chitosan dressing, by lyophilization. The resulting dressing was analyzed for morphology, porosity, pore volume, surface area and biodegradability. Higher surface area and porosity of the dressing facilitated its partial biodegradation by enzymatic action. In vitro cellular investigations with Human Dermal Fibroblasts (HDF) confirmed the safety of the dressing for wound healing applications. Human Thrombin-Antithrombin (TAT) based in vitro ELISA assay, for evaluating the hemostasis activity, illustrated an accelerated hemostasis activity, through higher thrombin generation and stable blood clot formation. The blood in contact with the dressing contained two-fold higher levels of TAT, as compared to that in contact with the TAT standard. Our results suggest the potential of the developed dressing for removing the necrotic tissues and accelerating the hemostasis activity, for efficient and rapid wound healing.