Phototherapeutic functionality of biocompatible graphene oxide/dendrimer hybrids

•Hybrid materials consisting of GO, DEN-OH and FA are successfully prepared.•Hybrids of GO/DEN-OH/FA exhibit one- and two-photon fluorescence emission.•Two-photon excitation on GO/DEN-OH/FA brings fluorescence in visible region.•GO/DEN-OH/FA can absorb NIR light and generate ROS that causes HeLa cells’ death.•Biocompatible GO/DEN-OH/FA has a potential as a photodynamic therapeutic agent. Hydroxyl-terminated fourth generation poly(amido amine) dendrimer and folic acid were chemically bound on graphene oxide. The resultant hybrids exhibited one-photon and two-photon fluorescence emission, since the excitation irradiation at 390 and 780nm on the hybrids brought a fluorescence emission in the visible region around 450nm. In addition, the photocytotoxicity study revealed that under the two-photon excitation at 780nm, the hybrids can absorb near-infrared light and generate reactive oxygen species which can oxidize the HeLa cells and cause their death, suggesting the phototherapeutic behavior. Cytotoxicity measurement revealed the high biocompatibility of the hybrids toward HeLa cells. Thus, the present biocompatible hybrids consisting of only dendrimer, folic acid and graphene oxide have potentials as photodynamic therapeutic agents for medical treatment.