▎ 摘　　要

Functionalized graphene oxide (GO) with folic acid-conjugated chitosan oligosaccharide (FACO) containing quaternary ammonium groups (GO-FACO(+)) was successfully prepared. The formation and composition of GO-FACO(+) were confirmed by FTIR, UV-Vis, AFM, TGA, and zeta-potential. Cell experiments show that cellular uptake of fluorescein FAM-labeled DNA sequence (FAM-DNA) delivered by GO-FACO(+) exhibits higher efficiency in doxorubicin chloride (Dox)-resistant MCF-7 human breast cancer cells (MCF-7/Dox) with folate receptor overexpressed than that delivered by chitosan oligosaccharide (CO)-functionalized graphene oxides (GO-CO+) without folic acid modification and in human lung cancer A549 cells with folate receptor negatively expressed. The loading efficiency of Dox on GO-FACO(+) was 568.4 mu g mg(-1) at the initial Dox concentration of 0.5 mg mL(-1), and in vitro release of Dox showed strong pH dependence. MDR1 siRNA transfected by GO-FACO(+) could efficiently knockdown the MDR1 mRNA and P-gp expression levels in MCF-7/Dox cells. GO-FACO(+) shows no obvious toxicity even at 500 mu g mL(-1). The sequential deliveries of MDR1 siRNA and Dox by GO-FACO(+) exhibited much higher cytotoxicity against MCF-7/Dox cells than only delivery of Dox by GO-FACO(+) when Dox concentration is lower than 25 mu g mL(-1), while excess 80 % cells were killed in the two cases when Dox concentration is higher than 30 mu g mL(-1). Taken together, this functionalized GO has potential applications for targeted intracellular delivery of anti-tumor drugs and genes.