An Intelligent Triple Assisted Gold Cluster-Based Nanosystem for Enhanced Tumor Photodynamic Therapy

Abstract

Photodynamic therapy (PDT) has been attracted a surge of research interest. However, there are several obstacles to limit the efficacy of PDT, such as hypoxic tumor microenvironment (TME), overexpressed glutathione (GSH), inefficient reactive oxygen species (ROS) generation, and so on. Herein, a smart responsive nanosystem was constructed, which was composed of Au₂₅ modified with triphenylphosphine (Au₂₅-TPP), catalase (CAT) and GSH-responsive diselenide-bridged mesoporous silica nanoparticles (Se-MSN). When the nanosystem arrived at tumor site, Se-MSN was degraded by the intracellular overexpressed GSH to release Au₂₅-TPP and CAT. The Au₂₅-TPP was targeted to mitochondria and generated ROS under the 808 nm NIR laser irradiation to kill tumor cells. Simultaneously, CAT could catalyze hydrogen peroxide to provide oxygen for relieving the hypoxia of TME. Besides, GSH was consumed by the diselenide bond to diminish the ROS loss. The above tactics (mitochondria targeting, hypoxia relieving and GSH consuming) jointly enhanced the PDT efficacy. The nanosystem showed distinct in vitro anticancer effect significantly stronger than other groups containing one or two assistance. Moreover, the in vivo results suggested that the tumors could be restrained obviously. The current study provides a new inspiration for constructing novel inorganic nanomedicines with multiple enhancement effect of PDT efficacy.