Dbait is a small double-stranded DNA molecule that has been utilized as a radiosensitizer to enhance the sensitivity of glioma to radiotherapy (RT).However,there is no effective drug delivery system to effectively overcome the blood-brain barrier (BBB).The aim of this study was to develop a gene delivery system by using the BBB and glioma dual-targeting and microenvironment-responsive micelles (ch-Kn(s-s)R8-An) to deliver Dbait into glioma for RT.Angiopep-2 can target the low-density lipoprotein receptor-related protein-1 (LRP1) that is overexpressed on brain capillary endothelial cells (BCECs) and glioma cells.In particular,due to upregulated matrix metalloproteinase 2 (MMP-2) in the tumor microenvironment,we utilized MMP-2-responsive peptides as the enzymatically degradable linkers to conjugate angiopep-2.The results showed that ch-Kn(s-s)R8-An micelles maintained a reasonable size (80-160 nm) with a moderate distribution and a decreased mean diameter from the cross-linking as well as exhibited low critical micelle concentration (CMC) with positive surface charge,ranging from 15 to 40 mV.The ch-K5(s-s)R8-An/pEGFP showed high gene transfection efficiency in vitro,improved uptake in glioma cells and good biocompatibility in vitro and in vivo.In addition,the combination of ch-K5(s-s)R8-An/Dbait with RT significantly inhibited the growth of U251 cells in vitro.Thus,ch-K5(s-s)R8-An/Dbait may prove to be a promising gene delivery system to target glioma and enhance the efficacy of RT on U251 cells.