Noncovalent assembly of reduced graphene oxide and alkyl-grafted mesoporous silica: an effective drug carrier for near-infrared light-responsive controlled drug release

In this paper, we report the assembly of reduced graphene oxide (RGO) and mesoporous silica grafted with alkyl chains (MSN-C18) to develop a new class of drug carriers which are able to deliver the loaded drug molecules into living cells upon exposure to near-infrared (NIR) light. This novel drug carrier consists of a structure formed by the noncovalent interaction of RGO caps and alkyl chains on the surface of MSN-C18. The capping of RGO sheets on mesoporous silica effectively blocks the pore mouths in the absence of NIR light. Conversely, and very importantly, the photothermal heating effect of RGO leads to a rapid increase in the local temperature upon exposure to NIR light, resulting in the weakening of the RGO sheet/alkyl chain noncovalent interaction. The RGO sheets will then be removed from the MSN surface, and the pores are uncapped. This uncapping mechanism makes it possible to release the loaded drug molecules upon irradiation with NIR light. In the present study, such a noncovalent assembly was examined by the use of doxorubicin as a model drug for NIR light-responsive intracellular controlled release studies. We believe that this noncovalent assembly will prove to be a promising drug delivery system for cancer therapy in the near future.