Electrospinning Chitosan-based Nanofibers for Biomedical Applications

Abstract

Chitosan-based, defect free, nanofibers with an average diameter between 60 and 120 nm were fabricated via electrospinning a blended solution of low molecular weight chitosan (LMWC) and polyethylene oxide (PEO). Several solution parameters such as acetic acid concentration, polymer concentration, and polymer molecular weight were investigated to optimize fiber consistency and diameter. These parameters were evaluated using the rheological properties of the solutions as well as the visual images produced by scanning electron microscopy (SEM) after electrospinning the solutions. Pure chitosan fibers were not able to be created due to highly viscous solutions that lacked the polymer concentration required to successfully produce fibers via electrospinning. Three molecular weights of chitosan were evaluated to find the molecular weight that would support the optimal amount of chain entanglement, polymer concentration, and viscosity required for electrospinning. The chitosan with the lowest molecular weight (150,000 Da) allowed for the greatest concentration of polymer in solution without producing a solution viscosity that could not be overcome by an electric field. SEM imaging demonstrated that generally as total polymer concentration increased, the number of beads decreased; and as chitosan concentration increased, fiber diameter decreased. PEO-chitosan blends demonstrating a time dependent separation in solution; as a result blended solutions were able to be electrospun with the weakest electric field and the least amount of complications when solutions were electrospun within 24 hours of initially being blended. The addition of NaCl created a charge shielding effect that reduced the time dependent effect. Predominately chitosan-based, fibers with an average diameter of approximately 100 nm were also successfully electrospun onto a preexisting polysaccharide film used in biomedical applications. Electrospinning upon the biomedical film allowed for the removal of the electrospun nanomesh from the collector plate with the nanofibers and mesh structure intact. The bicomponent electrospun nanomesh created in this study is of particular interest in tissue engineering and wound healing applications.