Wenqiang Xue,1,* Jinglei Du,2,* Yingying Wei,2 Shizhao Zhou,2 Shicai Wang,4 Yongzhen Yang,3 Lin Chen,3 Shiping Yu2 

1Department of Interventional Therapy, Shanxi Provincial People’s Hospital, Taiyuan, 030001, People’s Republic of China; 2Department of Interventional Therapy, Shanxi Province Cancer Hospital/ Shanxi Hospital Affiliated to Cancer Hospital, Chinese Academy of Medical Sciences/ Cancer Hospital Affiliated to Shanxi Medical University, Taiyuan, 030001, People’s Republic of China; 3Key Laboratory of Interface Science and Engineering in Advanced Materials, Ministry of Education, Taiyuan University of Technology, Taiyuan, 030024, People’s Republic of China; 4Department of Interventional Therapy, Taiyuan Central Hospital, Taiyuan, 030001, People’s Republic of China

*These authors contributed equally to this work

Correspondence: Yongzhen Yang, Key Laboratory of Interface Science and Engineering in Advanced Materials, Ministry of Education, Taiyuan University of Technology, Taiyuan, 030024, People’s Republic of China, Email yangyongzhen@tyut.edu.cn Shiping Yu, Department of Interventional Therapy, Shanxi Province Cancer Hospital, Shanxi Hospital Affiliated to Cancer Hospital, Chinese Academy of Medical Sciences, Cancer Hospital Affiliated to Shanxi Medical University, Taiyuan, 030001, People’s Republic of China, Email yushiping@sxmu.edu.cn

Background: Small interfering RNA (siRNA) provides a new method for anti-tumor therapy by targeting Survivin gene in liver cancer. However, free Survivin siRNA is easily degraded and cleared by endonucleases or macrophages in the blood circulation. Therefore, it is urgent to construct a safe and efficient delivery system to achieve effective transfection of Survivin siRNA.
Methods: In this study, cationic carbon dots (CCDs) with active targeting ability (FA-PEI-CDs) were designed and prepared using carbon dots (CDs), polyethyleneimine (PEI), and folic acid (FA). Then, Survivin siRNA was loaded by electrostatic adsorption to design a gene-loaded complex with gene silencing effect (FA-PEI-CDs@Survivin siRNA).
Results: As FA-PEI-CDs had good dispersibility, an average diameter of about 21.71 nm and a zeta potential of 5.11 mV. They had good proton buffering capacity and excellent biocompatibility and could not cause erythrocyte hemolysis and thrombosis. When FA-PEI-CDs were mixed with Survivin siRNA at a mass ratio of 2:1, they can completely load siRNA without being interfered by polyanion in vivo and avoid the degradation of siRNA by serum or intracellular nuclease, which significantly increased the circulation time of siRNA in blood. Meantime, when the mass ratio of FA-PEI-CDs to Survivin siRNA was 3:1, the maximum transfection efficiency was 22.8% and 28.5% in HL-7702 cells and HepG2 cells, respectively. In vitro cell experiments confirmed that the gene complex can specifically kill tumor cells without damaging normal liver cells. In vivo tumor inhibition experiments further confirmed that FA-PEI-CDs@Survivin siRNA can cause tumor cell necrosis and reduce the expression of Survivin protein.
Conclusion: In summary, FA-PEI-CDs can carry Survivin siRNA to achieve tumor gene silencing therapy, which will expand the treatment of liver cancer and provide a new idea for carbon nanomaterials in biological genetic engineering.

Keywords: cationic carbon dots, survivin siRNA, active targeting, liver cancer