Acid-responsive Nanocomplex Mediated Codelivery Of Cardiogreen/miRNA-21 Inhibitor For Enhanced Cancer Therapy

Cancer is one of the most serious diseases that endanger the human health.Compared with traditional therapeutic methods such as surgery,chemotherapy,and radiotherapy,new treatment techniques play an increasingly important role.Among them,gene therapy and phototherapy are widely used due to their low toxicity,high efficiency and controllability.It had been revealed that high expression of mi RNA-21 in a variety of cancer cells and it can be downregulated by its inhibitor mi RNA-21 i,thus regulating the apoptosis signaling pathway,promoting apoptosis,and inhibiting proliferation,invasion and metastasis.Photodynamic therapy produces reactive oxygen species(ROS)which can induce cell apoptosis.At the same time,photothermal therapy can increase the local temperature of the tumor site to effectively ablate the tumor.Therefore,the gene-photo combination therapy can achieved much higher kill efficiency of cancer.In order to realize the gene-photo combination therapy in an orderly and spatiotemporal manner,this thesis uses graphene oxide(GO)as a scaffold to design acid-responsive and charge reversible nanocarriers with layer-by-layer methods and then simultaneously load ICG and miRNA-21 i to construct the co-transport complexes(denoted as GPCP/miRNA-21i/ICG).Polylysine(PLL)is chemically linked on the surface of GO and then form an amide bond with citraconic anhydride(Cit),baring negatively charge,and PAMAM was assembled through electrostatic adsorption.Zeta potential,dynamic light scattering(DLS),polymer dispersity index(PDI),atomic force microscope(AFM),and transmission electron microscope(TEM)characterization revealed that the particle was curled into a sphere(about 150 nm in lateral dimension and about 4 nm in thickness).PLL and PAMAM were calculated to be about 36 % and25 % according to the thermogravimetric analysis(TGA),respectively.The agarose gel electrophoresis demonstrated that miRNA-21 i can be completely adsorbed by PAMAM and protected from serum and DNase I degradation.The ICG drug loading rate was about 75%,and ICG can be released once in acid environment.Moreover,the complex had good light-to-heat conversion efficiency and fluorescence imaging capacity.The in vitro cellular experimental results showed that the endocytosis of the nanocomplex was time-dependent.And it escaped from the lysosomal at 36 h,released into the cytoplasm and down-regulated endogenously high expression of miRNA-21.The phototherapy effect can be fully utilized,and the cell survival rate after the combination of the twomethods is only 17.33%.Moreover,the in vivo assay demonstrated the high anticancer efficiency against the MDA-MB-231 breast cancer mediated by GPCP/miRNA-21i/ICG..The study shows that the acid-sensitive nanocomplex GPCP/mi RNA-21i/ICG can achieve high efficiency of gene-photo combination therapy,which has great potential in the field of smart nanomedicine for cancer treatment.