Interaction between Biocompatible Graphene Oxide and Live Shewanella in the Self-Assembled Hydrogel: The Role of Physicochemical Properties.

Abstract

Understanding the interaction of graphene materials with bacterial cells is crucial for exploiting their environmental applications. Meanwhile, knowledge on the mechanism of graphene oxide (GO) action to bacteria is still incomplete. This study focused on the inter-relationship of biocompatible GO and the well-known dissimilatory metal-reducing bacteria Shewanella, in view of the biographene hydrogel (BGH), a self-assembly of GO and live bacteria. The results showed that, among various inter-related physicochemical properties of GO, the sheet area determined the bacterial survival and the gelation potential with the same Shewanella strain. For the biocompatible GO sheet above 0.30 μm2, the larger the GO, the higher the speed of BGH assembling. Only 22 h was needed to obtain BGH using GO with an average area of 1.83 μm2 (maximum in this study). The GO oxidation degree was found to be another critical factor affecting whether BGH formed or not, with a referential threshold of C/O > 1.75. Finally, surface force of GO was detected and correlated with the bacterial adhesion behavior for the first time, confirming that the large GO in the low oxidation state has high resultant force to attract bacteria. All these findings pave a promising way to develop a GO-bacteria complex like BGH to treat industrial wastewater in the future.