Engineering of Porous Silica Coated Gold Nanorods by Surface-Protected Etching and Their Applications in Drug Loading and Combined Cancer Therapy

Core–shell nanostructures, specifically gold nanorods coated with porous silica (GNR@p-SiO2), were successfully fabricated by surface-protected etching. The nanostructures, photothermal effects, drug loading and drug release behaviors, cellular uptake, and combined chemo–photothermal therapy were investigated. The results showed that the as-prepared GNR@p-SiO2 had a uniform porous silica outer layer. Etching process could be modulated by adjusting the etching time, concentrations of etching agents, and concentrations of protective agents. With doxorubicin (DOX) as the model drug, the drug loading capacity reached 18.9%, which was dependent on the DOX concentrations. The drug release profiles were dual stimulus-responsive to pH and laser irradiation. In addition, the GNR@p-SiO2 nanoparticles were biocompatible and effectively internalized by cancer cells. Compared with chemotherapy or photothermal therapy administered individually, combined chemo–photothermal therapy using GNR@p-SiO2 exhibited higher efficiency in killing cancer cells both in vitro and in vivo. Therefore, surface-protected etching is a powerful method for preparing core–shell nanostructures capped with mesoporous silica for combined cancer chemo–photothermal therapy.