Search

Highlights • The remarkable biomedical applications of chitosan are discussed. • The electrospinning process for chitosan and a chitosan blend are reported. • The application of films and membranes of chitosan for wound dressings is described. • In vivo, in vitro studies and drug delivery applications of chitosan are reviewed. Abstract This review outlines new developments in the biomedical applications of environmentally friendly ('green') chitosan and chitosan-blend electrospun nanofibers. In recent years, research in functionalized nanofibers has contributed to the development of new drug delivery systems and improved scaffolds for regenerative medicine, which is currently one of the most rapidly growing fields in all of the life sciences. Chitosan is a biopolymer with non-toxic, antibacterial, biodegradable and biocompatible properties. Due to these properties, they are widely applied for biomedical applications such as drug delivery, tissue engineering scaffolds, wound dressings, and antibacterial coatings. Electrospinning is a novel technique for chitosan nanofiber fabrication. These nanofibers can be used in unique applications in biomedical fields due to their high surface area and porosity. The present work reviews recent reports on the biomedical applications of chitosan-based nanofibers in detail. [ABSTRACT FROM AUTHOR]

Mass fabrication of sodium alginate nanofibers using single-nuzzle electrospinning process is an open challenge mainly due to its inter- and intramolecular hydrogen bonding, rigid chain conformation and low solubility. In this regards, we synthesized sodium sulfated alginate (SSA) through sulfation of hydroxyl functional groups of alginate. Not only decreases the hydrogen bonding density through the sulfation reaction, but the sulfated alginate also demonstrates more solubility in aqueous media compared to the pristine alginate. Beside the sulfation of alginate, its electrospinnability in combination with polyvinyl alcohol (PVA) significantly improves. In contrast to the neat alginate, concentrated aqueous solutions of sulfated alginate, 10 wt%, can be easily prepared and electrospun to obtain nanofibers of sulfated alginate. In this regards, facile fabrication of electrospun nanofibers of alginate derivatives with 50 wt% content in dry electrospun mat of SSA/PVA using single-nuzzle electrospinning and flow rate of 5 mL h −1 was developed for the first time. [ABSTRACT FROM AUTHOR]

Traditionally, the carrageenan fibers were prepared by process of extracting, drying, dissolving of carrageenan power and wet spinning process of fibers. However, in this study, carrageenan fibers were prepared by carrageenan solution directly from the extraction of Chondrus , without the steps of precipitation, and drying. The properties of carrageenan powder, spinning solution and carrageenan fibers were characterized with zeta potential, NMR, FTIR, dynamic light scattering (DLS), SEM, tensile testing and energy dispersive spectrometer (EDS). The results showed that the Chondrus contained mainly iota-carrageenan. The extraction of Chondrus was a uniform liquid with good properties of a solution, which was suitable as a spinning solution. The so prepared carrageenan fibers possessed good morphology and tensile properties. The excellent tensile properties of the carrageenan fibers were attributed to the combination of sulfate ester in the carrageenan and barium ions in the coagulation and then form a three-dimensional network structure. [ABSTRACT FROM AUTHOR]

Quite recently, the Ioncell-F process, a novel and promising Lyocell fibre process, has been developed. The ionic liquid 1,5-diazabicyclo[4.3.0]non-5-enium acetate ([DBNH]OAc) utilized in this process, was identified as an excellent cellulose solvent for dry-jet wet fibre spinning. Fibres spun from cellulose-[DBNH]OAc solution have shown excellent mechanical properties. Herein, various structural features of these ionic liquid-based fibres were analyzed and correlated with their mechanical properties. The highest slope of tenacity increase of these Ioncell-F fibres (from birch wood) observed at low draw ratios (DRs), while a continuous but slower increase occurs to partly very high draws. The improvements in the mechanical properties do not seem to correlate with changes in the crystallite size or the crystalline orientation based on wide-angle X-ray scattering (WAXS) results. More significant differences were seen for the sample crystallinity, the amorphous orientation (measured by birefringence), the orientation of the voids, the specific surface (measured by small-angle X-ray scattering (SAXS)), and the sorption/desorption properties of the fibres. [ABSTRACT FROM AUTHOR]

Motivated by the extensive application of agar, this work developed a wet-spinning process to fabricate micro-scale fibers using the gelation process of agar. The effect of three vital spinning parameters, namely dope concentration, coagulation bath composition, and fiber post-processing on morphological properties, tensile properties and chemical structure of the fiber have been discussed. The concentration of agar was determined by the results of rheological measurement. The addition of barium chloride in the coagulation process improved the mechanical properties of fibers as compared to deionized water as coagulation. The agar fibers immersed in amino silicone demonstrated significantly showed better mechanical properties compared to the agar fibers only immersed in ethanol. The physical and chemical properties of agar fibers were characterized by X-ray diffraction, FTIR, tensile testing, and SEM. The results showed that excellent agar fibers with several potential applications can be produced with amino silicone modification in optimum coagulation bath. [ABSTRACT FROM AUTHOR]

Man-made lignocellulosic fibres were successfully prepared from unbleached birch kraft pulps by using the Ioncell-F technology. Pulps with different lignin content were produced by tailored kraft pulping with varying intensity. The degree of polymerization of the pulps was adjusted by acid-catalyzed hydrolysis and electron beam treatment. All substrates were completely soluble in 1,5-diazabicyclo[4.3.0]non-5-enium acetate ([DBNH]OAc) and the respective solutions were spinnable to yield fibres with good to excellent mechanical properties despite the use of only mildly refined wood pulp. The tensile properties decreased gradually as the lignin concentration in the fibres increased. Changes in the chemical composition also affected the structure and morphology of the fibres. Both the molecular orientation and the crystallinity decreased while the presence of lignin enhanced the water accessibility. The effects of the crystallite size and lignin content on monolayer water adsorption are discussed. [ABSTRACT FROM AUTHOR]

By blending cellulose and duck feather in the common solvent 1-allyl-3-methylimidazoloium chloride, a regenerated composite fibre has been developed with improved fibres over regenerated cellulose fibres (RCF). The mechanical properties of composite fibre was shown to be better than RCF with a 63.7% improvement in tensile strain. Here, we thoroughly characterise the composite fibre and show that the composite fibre has many advantages over RCFs both from a spinning perspective and as a regenerated fibre. [ABSTRACT FROM AUTHOR]