▎ 摘　　要

Development of biocompatible surface coating is critical to engineer various functional nanomaterials for biomedical applications. Here, we present a new surface chemistry of graphene by covalently conjugating graphene oxide (GO) with dextran (DEX), a biocompatible polymer widely used for surface coating of biomaterials. Compared with GO, the graphene-dextran (GO-DEX) conjugate shows reduced sheet sizes, increased thickness and significantly improved stability in physiological solutions. Cellular experiments uncover that DEX coating on GO offers remarkably reduced cell toxicity. We further label GO-DEX with a radioactive isotope, I-125, for in vivo tracking in animal studies. It is found that GO-DEX accumulates in the reticuloendothelial system (RES) including liver and spleen after intravenous injection, and importantly, shows obvious clearance from the mouse body within a week without causing noticeable short-term toxicity to the treated animals. Our results suggest that this DEX coating method on GO may potentially be useful to the further development of novel graphene-based bioconjugates for various biomedical applications. (C) 2011 Elsevier Ltd. All rights reserved.