A method of inducing autophagy in a cell is achieved by contacting the cell with graphene oxide (GO) in an amount effective to induce autophagy in the cell, wherein the cell expresses at least one of TLR-4 (Toll-like receptor 4) and TLR-9 (Toll-like receptor 9). Differences between autophagy triggered by GO and other conventional agonists such as rapamycin have been observed. GO may activate autophagy in some cells that may not be triggered by rapamycin. The cell reveals no apparent apoptosis after treatment of the graphene oxide. A method of activating a Toll-like receptor in a cell is also herein provided.
