Graphene oxide activated by 980 nm laser for cascading two-photon photodynamic therapy and photothermal therapy against breast cancer

Combinational applying photodynamic therapy (PDT) and photothermal therapy (PTT) have been extensively studied, while simultaneously exciting with a single wavelength NIR laser remains challenges. In this study, PEGylated nano graphene oxide co-loaded with photosensitizers (PS) and two-photon compound was developed as a theranostic nanomedicine GO-PEG(TP) against cancer. Two-photon compound could convert near-infrared laser into visible light for exciting PS thus achieved deeper therapeutic depth. The size, morphology and drug release profile of GO-PEG(TP) were characterized. The photoactivity of PS and two-photon compound get quenched on the graphene sheet, whereas activated quickly after releasing from carrier. Such combined therapy shows blasting of 4T1 murine breast cancer cells and induced large population of apoptosis. Ex vivo distribution and in vivo thermographic images were analyzed by using GO-PEG(TP) as probe, on subcutaneously 4T1 tumor bearing mice. Combinational therapy and histology examination reveal the antitumor property and biosafety of GO-PEG(TP).