Abstract:
Nano-cobweb fibers supported by conventional electrospun fibers are 2D membranes with structure similar to spider webs, for which the average diameter is less than 50 nm and can be potentially applied in the fields of fine filter, sensor, tissue engineering, high performance protective clothing etc. Herein, polybutyrolactamide (PBL) and chitosan (CS), both derived from biomass and are biodegradable, were applied to construct the electrospun composite fiber membranes with nano-cobweb structure. The effects of blending ratio of PBL to CS and the solution concentration on solution properties as well as the fiber morphology and membrane structure were investigated. The cell compatibility of the electrospun composite fiber membranes was also discussed. It is found that the addition of polycationic CS improved the spinnability of PBL/FA solutions and the composite fibers could be continually electrospun. As the CS mass fractiong was increased, the conductivity and viscosity of the solutions both increased. Varying CS mass fraction in PBL/CS blend from 10% to 30% at fixed solution mass fraction of 8.0%, the solution viscosity increased even more than the conductivity did, and only fiber membranes without nano- cobweb structure were obtained. Increasing solution concentration also increased the solution conductivity and viscosity, but the increase in conductivity was more significant, which proved to be beneficial to electrospinning composite fiber membranes with nano-cobweb structure. When CS mass fraction in PBL/CS blend was 10%, increasing solution mass fraction from 8.0% to 9.0% didn’t help to get nano-cobweb structure. The nano-cobweb structure with breakages was obtained when CS mass fraction was 20% at the solution mass fraction of 10.0%. The composite fiber membranes with perfect nano-cobweb structure and 100% coverage could be electrospun by further increasing CS mass fraction and solution mass fraction to 30% and 11.0%, respectively. The results of Fourier transform infrared (FT-IR) spectroscopy and X-ray diffraction (XRD) indicated that the addition of CS inhibited the crystallization of PBL and the composite fibers of low crystallinity and even amorphous. The results of 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide(MTT) assay confirmed that PBL/CS electrospun composite fiber membranes were noncytotoxic and could promote cell proliferation, especially for those with nano-cobweb structures. Such biobased and biodegradable composite fiber membranes are promising materials in the field of wound-dressing, nerve repairing and regenerative tissue engineering.