WATER-SOLUBLE GRAPHENE THROUGH POLYGLYCIDOL GRAFTING AT THE PERIPHERY FOR BIOMEDICAL APPLICATIONS

摘要

For applications of nanocarbons in biology and medicine, such as imaging probe and drug carrier, they have to be well solubilized under physiological environment. In this context, surface chemical functionalization has been extensively investigated to impart strong hydrophilicity to nanocarbons. We found recently that polyglycidol (PG) grafting on the surface of nano diamond (ND) made ND highly soluble in phosphate buffer [1]. The aqueous solution is very stable for months and the solubility of the PG-functionalized ND (NDPG) is as high as 16 mg/mL in phosphate buffer saline (PBS), which is 400 times larger than that of the PEG-functionalized ND [2]. In this paper, we will present our recent result of PG grafting at the periphery of graphene through ring-opening polymerization of glycidol to prepare PG-functionalized graphene (G-PG) soluble in phosphate buffer. We carried out the PG-functionalization under similar reaction conditions to those of the ND-PG, but used commercial graphite as a starting material. On the PG grafting, exfoliation of graphite to graphene proceeded simultaneously, providing G-PG. The obtained G-PG was soluble in not only water, but also in phosphate buffer. Structure of G-PG in the aqueous solution was confirmed by atomic force microscopy (AFM) and scanning tunneling electron microscopy (STEM).