(162ap) Functional Magnetic Graphene Oxide for Dual Targeted Chemo-Gene Therapy of Brain Tumors

In this study, we develop magnetic graphene oxide (mGO) for pH-responsive drug delivery and RNA interference (RNAi) for dual targeted delivery of a chemical chemotherapeutic drug (CPT-11) and a gene drug (SLP2 shRNA) for brain cancer therapy. This dual targeting (magnetic targeting and GRP ligand targeting) drug delivery system was used for glioblastoma treatment using luciferase gene-transfected U87 human primary glioblastoma cell line. The nano-carriers were fully characterized from the chemical and physical points of view at each step of preparation. Moreover, the fully functionalized MGOs were shown to exert dual targeting functional cytotoxic and gene silencing activity both in vitro and in vivo. Drug loading efficacy was optimized followed by pH-responsive drug release study, which confirmed enhance drug release at a low pH value as encountered after endosomal uptake. From intracellular uptake study using fluorescently labelled nano-carriers and confocal microscope observation, the ligand targeting efficacy was confirmed. Also, staining with LysoTracker for endosomal escape of the nano-carrier, trafficking of shRNA from endosomes into the cytoplasm within a short period of time was confirmed, which was reported to be major rate-limiting step for many RNAi delivery approaches. In vitro cell culture study showed that mGO-GRP/CPT11/shRNA exerts enhanced cytotoxicity from flow cytometry and Western blot analysis. Efficient transfection efficiency of U87 by mGO/shRNA as high as that of a commercial transfection kit was observed using SLP2 shRNA plasmids carrying green fluorescence gene while successful SLP2 gene silencing by mGO/shRNA was revealed from Western blot to be supported by inhibition of U87 cells migration. Finally, in vivo study using tumor xenograft models with subcutaneously implanted U87 cells in nude mice revealed synergistic brain tumor treatment efficacy using mGO-GRP/CPT11/shRNA from survival rates, IVIS bioluminescence intensity, MRI analysis and histology.