Construction Of Cancer Cell Membrane-camouflaged Nucleic Acid Nanogels And Their Antitumor Therapy Application

Small interfering RNA(si RNA)can selectively target and downregulate disease-causing genes,holding great potential in cancer therapeutics.Nucleic acid functional nanomaterials can be used as ideal gene delivery carriers due to their molecular recognition ability,structure programmability and great biocompatibility.However,the efficacy of gene therapy was limited by low gene delivery efficiency and physiological barriers.To address these issues,cell membrane coating technology has gradually become an effective biomimic strategy,which brings new prospect for the clinical application of gene therapy.This thesis focuses on the synthesis,properties and antitumor effect of cancer cell membrane-camouflaged nucleic acid nanogel.The main research work is summarized as follows:In the first chapter,we overviewed the unique advantages and research progress of gene therapy and summarized the structures and functions of gene delivery carriers.Based on the problems and challenges in the field of clinical gene therapy,we proposed this research work.In the second chapter,we first obtained nucleic acid hybrid nanogel by the self-assembly of Y-shaped branched DNA(Y-DNA)and si RNA mediated by tannic acid(TA),and then modified the cancer cell membrane on the surface.A cancer cell membrane-camouflaged nucleic acid nanogel(nanogel@A549m)was synthesized.The material was regular spherical structure with a hydrodynamic diameter of 170 nm,and showed excellent physiological stability and biocompatibility.By simulating the intracellular environment in vitro,it was verified that the material could release gene drugs successfully under the dual-response of acid and enzyme,which laid the foundation for gene therapy.In the third chapter,we characterized the therapeutic effect of nanogel@A549m at the cellular level in detail.First,we proved that it could successfully escape the phagocytosis of immune cells and had homologous targeting ability due to the camouflage of cancer cell membrane.Then the antitumor mechanism was analyzed:TA was proved to be able to induce apoptosis of cancer cells by apoptosis experiment;RNA interference experiments showed that si RNA could be effectively delivered into cells and down regulate the expression of PLK1 kinase.The gene interference efficiency was as high as 70%.The cytotoxic experiment showed that the material could seriously inhibit the growth and proliferation of A549 lung cancer cells,and had obvious killing effect.In the fourth chapter,we characterized the antitumor effect of nanogel@A549m in vivo.The half-life of material in the blood was up to 2 hours,and it had a significant enhancement of tumor accumulation effect.It was proved that the material could down-regulate the expression of PLK1 kinase and induce cancer cell apoptosis.Moreover,the remarkable suppression of tumor growth was achieved in a xenograft mouse model of lung cancer.More importantly,it would not have significant toxicity and side effects on other tissues and organs of the organism.In the last chapter,we summarized and forecasted the work of this thesis.The reported nanogel@A549m has ability of targeted gene drugs delivery and significant antitumor effect.We believe that the platform shows great potential for cancer therapy and will provide new ideas for the construction of nucleic acid functional nanomaterials.