Preparation, characterization, and in vitro and in vivo evaluation of cellulose/soy protein isolate composite sponges

A series of cellulose/soy protein isolate (SPI) sponges was prepared using a freeze-drying process. The effect of the SPI content on the structure of the sponges was characterized by Fourier transform infrared spectrometry (FT-IR), X-ray diffraction analysis (XRD) and scanning electron microscopy (SEM). It showed that the sponges were porous in structure, and that the size of the pores increased and the thickness of the pore walls decreased as the SPI content of the sponges increased. The biocompatibility and biodegradability of the sponges were evaluated in vitro and in vivo. The cell culture experiment and SEM observations showed that L929 fibroblast cells grew and spread well on the surface and cross-section of the composite sponges. The results from MTT (3-[4,5-dimethyl-2-thiazoly1]-2,5-diphenyl-2H-tetrazolium bromide) assay indicated that the cell viability of L929 cultured in extracts from SPI-containing sponges was higher than that from the pure cellulose sponge. The historical analysis and SEM observation revealed that the SPI-containing sponges implanted from 1 to 8 months in rats exhibited better in vivo biocompatibility and biodegradability than the pure cellulose sponge. This was due to the incorporation of SPI into cellulose and to the freeze-drying process which formed large pores and thin pore walls in the composite sponges, promoting the migration of cells and tissue into the sponges, leading to gradual fusing with the implants. The new cellulose/SPI sponges thus have potential applications as biomaterials with good biocompatibility and biodegradability.