GSH-triggered sequential catalysis for tumor imaging and eradication based on star-like Au/Pt enzyme carrier system

Distinctively different metabolism between tumor cells and normal cells endows tumor tissues unique microenvironment. In this regard, we have successfully prepared a sequential catalytic platform based on Au/Pt star for tumor theragnostic. The multifunctional probes consisted of a gold/platinum star-shaped core (Au/Pt star) conjugated with a GSH-sensitive disulfide bond (S-S), a targeting ligand (rHSA-FA), a near-infrared fluorophore (IR780) and glucose oxidase (GOx). When systemically administered in a xenografted murine model, the probes specifically targeted the tumor sites. As the disulfide linker was cleaved by intracellular GSH, the IR780 molecules could be released for photo-thermal therapy & photodynamic therapy (PTT&PDT) and imaging. Subsequently, the Pt nanolayer of the Au/Pt star and the GOx formed a sequential catalytic system: GOx effectively catalyzed intracellular glucose by consuming oxygen to generate H2O2 and enhance the local acidity, and the Pt layer exhibited peroxidase-like property to catalyze H2O2 producing toxic center dot OH for tumor oxidative damage. Here we demonstrated that our probes simultaneously possessed a GSH-sensitive release, real-time imaging ability, and synergetic cancer starving-like therapy/enzyme oxidative therapy/PTT/PDT features, which provides a potential strategy for effective tumor theragnostic.