Fluorescent Phthalocyanine–Graphene Conjugate with Enhanced NIR Absorbance for Imaging and Multi-Modality Therapy

There has been increasing interest in design theranostic agents for combining diagnosis and different treatment modalities, especially for development physiological stable materials to avoid instability and dissociation in biological environment. Herein, a covalently connected silicon phthalocyanine (SiPc) and graphene oxide (GO) conjugate SiPc-GO is designed and synthesized via conjugation reaction to render stability. This novel highly water-soluble material displays intrinsically fluorescence and synchronous photothermal-photodynamic therapy (PTT/PDT) effect, along with 3-fold higher near-infrared (NIR) absorbance comparing to pristine GO. In vitro cell studies show that SiPc-GO could cause intracellular fluorescence, photothermal effect and reactive oxygen species (ROS) generation synchronously, and effective photoablation of cancer cells could be triggered by both 671 and 808 nm lasers via synergistic PTT/PDT or NIR photothermal effects, respectively. In vivo systemic administration in MCF-7 xenograft mice shows that SiPc-GO could effectively accumulate in the tumor regions and induce the inhibition of tumor growth violently after laser irradiation. This work establish SiPc-GO as a multimodality nanosized photomedicine for cancer imaging, synergistic PTT/PDT, and NIR photothermal therapy.