Surface Functionalization, Toxicology Evaluation And Biodegradation Behavior Research Of Graphene Derivatives

With the increasing interests of using graphene and its derivatives in the area ofbiomedicine, the systematic evaluation of their potential risks and impacts to biologicalsystems is becoming critically important. In this work, we carefully study how surfacecoatings affect the cytotoxicity and extracellular biodegradation behaviors of grapheneoxide (GO) and its derivatives.Although naked GO could induce significant toxicity to macrophages, coatingthose two-dimensional nanomaterials with biocompatible macromolecules such aspolyethylene glycol (PEG) or bovine serum albumin (BSA) could greatly attenuate theirtoxicity, as independently evidenced by several different assay approaches especiallythe covalently linked GO-PEG. On the other hand, although GO can be graduallydegraded to smaller sheets through enzyme induced oxidization by horseradishperoxidase (HRP), both PEG and BSA coated GO or reduced GO (RGO) are ratherresistant to HRP-induced biodegradation which may be related to the steric hindranceby surface molecules.In order to obtain biocompatible functionalized GO that can still undergoenzymatic degradation, we covalently conjugate PEG to GO via a cleavable disulfidebond, obtaining GO-SS-PEG with negligible toxicity and considerable degradability,promising for further biomedical applications.