Gold Nanoparticle/Graphene Oxide Hybrid Sheets Attached on Mesenchymal Stem Cells for Effective Photothermal Cancer Therapy

Cell-mediated nanoparticle delivery has been proposed for an effective cancer therapy. However, there are limitations in loading nanoparticles within cells as the internalized nanoparticles cause cytotoxicity and leak out of the cells via exocytosis. Here, we introduce hybrid sheets composed of gold nanoparticles (AuNPs) and graphene oxide (GO), which stably adhere to the cell surface and exhibit a remarkable photothermal effect. To form AuNP/GO sheets in which GO is sandwiched between two AuNP monolayers, AuNPs are coated with alpha-synuclein protein and subsequently adsorbed onto GO sheets. Attaching AuNP/GO sheets to the tumor-tropic mesenchymal stem cell (MSC) surface enhances the loading efficiency of AuNPs in MSCs by avoiding the cytotoxicity and exocytosis issues. Furthermore, the tight packing of AuNPs on microscaled GO sheets enhances the photothermal effect via strong plasmon coupling between AuNPs. The injection of AuNP/GO sheet-attached MSCs into tumor-bearing mice significantly improves the photothermal therapeutic efficacy by delivering larger amounts of AuNPs to the tumor and generating higher heat at the tumor region compared to injection of AuNP-internalized MSCs. The system of attaching AuNP/GO hybrid sheets to the tumor-tropic cell surface may be an effective platform for cancer therapy.