An intelligent and biocompatible photosensitizer conjugated silicon quantum dots-MnO2 nanosystem for fluorescence imaging-guided efficient photodynamic therapy

Photodynamic therapy (PDT) has been widely applied in cancer treatment due to minimal invasion, negligible side effects and specific tumor ablation. However, the treatment efficiency has been hindered by hypoxia in solid tumors, hydrophobic photosensitizers and their real time tracking. In this paper, we constructed an intelligent and biocompatible bovine serum albumin (BSA)-Ce6-Si QDs-MnO2 (BCSM NPs) nanocomplex as a pH/H2O2 responsive photosensitizer nanocarrier to modulate tumor hypoxia for fluorescence imaging-guided efficient PDT. This versatile nanosystem not only enhanced the loading capacity of the photosensitizer and the formation of cytotoxic singlet oxygen (O-1(2)) owing to the intelligent production of oxygen catalyzed by MnO2 from the endogenous H2O2, but also performed as a dual functional fluorescence and Magnetic Resonance imaging (MRI) probe. In vivo experiments in nude mice further confirmed that BCSM NPs significantly inhibited the growth of HeLa bearing-tumors compared to free Ce6. The results highlight the great potentail of multifunctional BCSM NPs for in vivo imaging as well as enhancing the photodynamic therapy efficiency.