Synthesis Of Multifunctional Intelligent Polymeric Gene Delivery System Responsive To Endogenous And Exogenous Stimuli For Active Gene Expression And Study On Their Properties As Gene Vectors

Gene therapy provides an alternative and effective method for treatment of genetic diseases and cancers that are refractory to conventional therapeutics.The success of gene therapy is largely dependent on the development of safe and effective gene delivery vectors for transporting genetic material from the blood stream to the cytoplasm or nucleus.Although non-viral gene delivery carriers can offer some advantages,such as safety and facile fabrication,they do not possess the same high gene transfection efficiency as viral vectors due to a lack of functionality to overcome extra-and intracellular gene delivery obstacles.On the basis of these disadvantages,researchers are developing ‘‘smart” non-viral gene-delivery carriers in order to overcome the physiological barriers and realize efficient gene transfection.These ‘‘smart'' stimuli-responsive carriers can undergo physical or chemical reactions in response to internal tumor-specific environments,such as pH conditions,redox potentials and enzymatic activations,as well as external stimulations,such as ultrasound,light,magnetic fields,and electrical fields.Furthermore,‘‘smart'' carriers can also be triggered by dual or multiple combinations of different stimuli.In this thesis,we attempt to compile a number of functional components into tandem tri-copolymeric material.Herein,?-cyclodextrin-functionalized poly(glycerol methacrylate)(PG)segment and quaternary amine-functionalized poly[(2-acryloyl)-ethyl-(p-boronic acid pinacol ester benzyl)diethylammonium bromide](BP)segment are schemed to complex DNA to formulate nanoscaled delivery system based on electrostatic interactions.The formulated polyplex is strengthened by the hydrophobic poly[2-(5,5-dimethyl-1,3-dioxan-2-yloxy)ethyl acrylate](PDM)segment,affording improved complex stability.To retrieve the polyplex from the entrapment from acidic and digestive endo/lysosomes,light-stimulated ROS-producing 4,4'-(1,2-diphenylethene-1,2-diyl)bis(1,4-phenylene)diboronic acid(TPE)and NQO1-catalysis ?-lapachone are installed in the cavities of cyclodextrin,respectively.Upon light irradiation/enzyme catalysis,TPE/?-lap is determined to produce abundant ROS,not only committing disruption of endo/lysosome membrane for polyplex escape from the entrapment but also inducing the transformation of the positive-charged BP to be negative charge.This charge conversion behavior,together with transformation of PDM to be hydrophilic responsive to acidic endosome pH gradient(pH 5.0),is envisioned to induce the dissociation of the electrostatically-assembled polyplex,thereby facilitating the release of DNA payload for the subsequent transcription machinery.This strategically-tailored and easily synthesized tandem tri-copolymer exhibit excellent gene expression activity and provide facile response to endogenous and exogenous stimuli for active gene expression.