Chitosan-based electrospun membranes: Effects of solution viscosity, coagulant and crosslinker.

Chitosan-based membranes were prepared via electrospinning technique using a low concentrated acetic acid solution as solvent and poly(ethylene oxide) as co-spinning agent. Different solutions were rheologically characterized and increasing the solution viscosity was found to correspond to a better-defined morphology. The membranes were first subjected to a coagulation process with different baths in order to stabilize chitosan and the mats were found not able to withstand a strongly basic environment. Subsequently, a physical and a chemical crosslinking approach were separately optimized to obtain stable mats whose composition was assessed via thermogravimetric and spectroscopic techniques, proving in both cases the elimination of the co-spinning agent. Above all, the ionically crosslinked mats represent a class of extremely promising biomedical products being probably highly biocompatible and characterized by thin and homogenous nanofibers with a diameter of 200 nm, thus showing the ideal structure to foster cell viability.

Preparation of composite alginate-based electrospun membranes loaded with ZnO nanoparticles.

In the present work alginate-based nanofibrous membranes embedding zinc oxide nanoparticles (ZnO-NPs) were prepared via electrospinning technique. ZnO-NPs were synthesized by means of a "green" sol-gel method by using alginate itself as stabilizing agent and characterized through UV-vis spectroscopy, thermogravimetric and morphological analysis. Formulations containing sodium alginate, poly(ethylene oxide) and ZnO-NPs were rheologically studied to identify the most suitable ones to be electrospun; alginate molecular structure played an important role on the solution spinnability due to the polysaccharide capability to establish electrostatic interactions and hydrogen bonds with ZnO-NPs. An innovative washing-crosslinking protocol was developed to obtain stable products which composition was assessed using Fourier Transform InfraRed spectroscopy and thermogravimetric analysis. Morphological investigation combined with EDX spectroscopy proved the obtained mats were highly porous and composed by thin homogenous nanofibers with a good distribution of the used nanofillers, thus representing potential products for several purposes (e.g. biomedical, pharmaceutical and environmental applications).