Photo- and pH-Triggered Release of Anticancer Drugs from Mesoporous Silica-Coated Pd@Ag Nanoparticles

A smart drug delivery system integrating both photothermal therapy and chemotherapy for killing cancer cells is reported. The delivery system is based on a mesoporous silica-coated Pd@Ag nanoplates composite. The Pd@Ag nanoplate core can effectively absorb and convert near infrared (NIR) light into heat. The mesoporous silica shell is provided as the host for loading anticancer drug, doxorubicin (DOX). The mesoporous shell consists of large pores, similar to 10 nm in diameter, and allows the DOX loading as high as 49% in weight. DOX loaded coreshell nanoparticles exhibit a higher efficiency in killing cancer cells than free DOX. More importantly, DOX molecules are loaded in the mesopores shell through coordination bonds that are responsive to pH and heat. The release of DOX from the core-shell delivery vehicles into cancer cells can be therefore triggered by the pH drop caused by endocytosis and also NIR irradiation. A synergistic effect of combining chemotherapy and photothermal therapy is observed in our core-shell drug delivery system. The cell-killing efficacy by DOX-loaded coreshell particles under NIR irradiation is higher than the sum of chemotherapy by DOX-loaded particles and photothermal therapy by coreshell particles without DOX.