808 nm near-infrared light controlled dual-drug release and cancer therapy in vivo by upconversion mesoporous silica nanostructures

The design of stimuli-responsive drug delivery systems has attracted much attention to improve therapeutic efficacy for clinical applications. Here an 808 nm NIR light responsive dual-drug system was designed for cancer treatment both in vitro and in vivo. Mesoporous silica coated NaYF₄:Yb_0.4/Tm_0.02@NaGdF₄:Yb_0.1@NaNdF₄:Yb_0.1 (UCNPs) with a core-shell structure (labeled as UCNPs@mSiO₂) was prepared and loaded with the antitumor drug doxorubicin (DOX). The surface of the composite was functionalized with β-cyclodextrin rings bridged by the light cleavable platinum(iv) pro-drug, thus blocking DOX inside the mesopores of silica. When excited by 808 nm NIR light, the emitted UV light from the UCNPs was used to activate the platinum(iv) pro-drug to gain higher toxicity platinum(ii) complexes and open the mesopores of silica (at the same time) to release DOX molecules. Both DOX and platinum(ii) complexes can kill cancer cells. This dual-drug delivery system may represent a new avenue for the application of UCNPs in photoactivated cancer therapy.