Synthesis, characterization and cytotoxicity of phosphorylcholine oligomer grafted graphene oxide

Using a random polymerization process on graphene oxide (GO), graphene oxide grafted with oligomers containing phosphorylcholine moieties (GO-PCn) was synthesized. The synthesis products were characterized by atomic force microscopy, Raman spectroscopy, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, thermogravimetric analysis and X-ray diffraction. The results revealed that the synthesized GO-PCn possessed greatly improved water solubility and remained stable in cell culture medium for several months. To evaluate the cytotoxicity of the GO-PCn, three cell lines (human umbilical vein endothelial cells, 264.7 murine macrophages and L929 murine fibroblasts) were cultured in different concentrations of GO and GO-PCn. GO-PCn demonstrated improved biocompatibility with all three cell lines. To investigate the mechanism of cellular uptake of the GO-PCn, fluorescein isothiocyanate-labeled GO-PCn was prepared. The results indicated that GO-PCn was incorporated by each cell type through endocytosis—a consequence of its near-micrometer size—and that it had no significant cytotoxicity.