Controlling physicochemical properties of graphene oxide for efficient cellular delivery

Efficient cellular endocytosis is indispensable for a drug delivery system. Graphene oxide (GO) is attracting considerable attention owing to its unique properties. However, GO tends to aggregate in physiological aqueous solutions and thus stabilization through functional molecules needs to be introduced. This research suggests a new strategy for utilizing GO as a drug carrier without a complicated surface modification process. A needle-like GO nanocarrier is developed through a conformational change of GO sheets in the cell growth medium with the aids of salt ions. A high surface area and sufficient number of functional groups of GO ensure the accumulation of doxorubicin hydrochloride (DOX) on the GO sheets. The drug loading capacity is measured through UV-vis spectroscopy. DOX-loaded GO sheets are visualized using confocal images and an AFM analysis. The conformational change and cellular uptake mechanism are studied with the help of TEM. The cytotoxicity and cellular uptake of the DOX-loaded GO needles are investigated on human dermal fibroblast (HDF) cells and the HeLa cancer cell line. GO needles demonstrate good biocompatibility of below a 100 μg/mL concentration, whereas DOX-loaded GO needles show a better anti-cancer capability than free DOX treatment owing to the enhanced cellular endocytosis of a 1D needle structure.