Biocompatible graphene nanosheets grafted with poly(2-hydroxyethyl methacrylate) brushes via surface-initiated ARGET ATRP

Using robust chemistry to graft polymer brushes on graphene nanosheets would promote the development of graphene nanomaterials as a versatile platform for biomedical applications. Based on surface-initiated activators regenerated by the electron transfer atom transfer radical polymerization (ARGET ATRP) technique, the study developed a protocol to prepare well-defined poly(2-hydroxyethyl methacrylate) (HEMA) brushes on chemically reduced graphene oxide surfaces. ATR-FTIR, XPS and TEM characterizations demonstrate tin(ii) 2-ethylhexanoate to be an efficient reducing agent that provides controlled polymerization with a significant decreased Cu catalyst usage (down to about 20 ppm), and prevents trace amounts of elemental Cu residue on the graphene surface. Fetal bovine serum protein absorption assay reveals the effect of brush backbone structure change to tune the interfacial interaction between graphene nanosheets and proteins. Further, NIH-3T3 fibroblast cell and human umbilical vein endothelial cell viability assays indicate that the obtained graphene nanosheets meet the biocompatibility requirements to support fibroblast cells, even human cells, attach and proliferate. The approach and the graphene-polymer brush hybrid developed in this work should open new opportunities for a broader range of biomedical applications of carbon nanomaterials.