Hydrothermal Reduction of Polyethylenimine and Polyethylene Glycol Dual-Functionalized Nanographene Oxide for High-Efficiency Gene Delivery

In this study, a physiologically stable dual-polymer-functionalized reduced nanographene oxide (nrGO) conjugate (PEG–nrGO–PEI, RGPP) with high efficiency of gene delivery is successfully synthesized through mixing PEGylated nanographene oxide (PEG–nGO, GP) and polyethylenimine (PEI, 25 kDa) solution under 80 °C for 2 h. This hydrothermal reduction of GP during PEIylation promotes the nucleophilic reaction between the amino moieties of PEI and the epoxy groups (or carboxylic groups) in GP and then forms C–NH– groups (or NH–CO groups) to covalently connect PEI and GP, which makes the RGPP nanocomposite more stable in physiological environments and has superior gene transfection efficiency compared with the nonhydrothermally reduced PEG–nGO/PEI conjugate (GPP) obtained by mixing GP and PEI under 20 °C for 2 h. Moreover, 808 nm laser irradiation (2 W/cm2) for 25 min increases ∼1.5-fold of gene transfection efficiency for RGPP but does not increase the gene transfection efficiency of GPP. Finally, RGPP is also...