In-situ growth of graphene on carbon fibers for enhanced cell immobilization and xylitol fermentation

Abstract In-situ growth of graphene on carbon fibers (GR/CF) carrier via exfoliation and regrowth of carbon was applied to modify the surface of CF for cell-immobilization. The structure and properties of GR/CF were investigated to establish the speculated mechanism of graphene in-situ growth on CF. Compared with the Raw-CF, GR/CFnormal as the optimized GR/CF enhanced immobilization efficiency (from 40.12 to 58.24%) attributing by larger specific surface area (3.645 m2∙g-1) and degree of moisture (0.82 g∙g-1), lower zeta potential (-29.7 mV) and contact angle (45.63°). Meanwhile, GR/CFnormal improved the cell vitality and biocompatibility of carriers, owing to the appearance of graphene and increased oxygen-containing groups. On the fermentation of immobilized Candida tropicalis with GR/CFnormal, the xylitol yield and volumetric productivity were improved from 30.63 to 44.78 g∙L-1 and 0.57 to 0.86 g∙L-1∙h-1, respectively. The average xylitol yield of batches fermentation immobilized with GR/CFnormal maintained approximately 80% of its highest result which improved 1.42 times than that of Raw-CF. In-situ growth of graphene on CF represents a promising method to prepare biocompatible carriers for multi-batch fermentation.