生物可降解核酸递送载体是生物医用材料领域的未来发展方向。尤其是可还原响应降解聚合物在细胞内吞后可以完全降解而显示出较低的细胞毒性。本项目突破传统逐步合成方法，探索在温和的反应条件下，以不同种类的含巯基引发剂（功能小分子、多糖、多肽或蛋白）与氨基化硫辛酸单体通过双硫交换反应构建系列富含氨基的可生物降解阳离子聚合物，再结合后修饰引入靶向功能的分子。通过探讨双硫交换反应制备方法，研究不同种类单体或引发剂对成像、多模式治疗的构效关系及其调控规律，最终构建不同种类、功能可调的、还原响应可降解核酸递送体系。本项目有望为构建多功能新型医用递送载体提供新思路。

Biodegradable polycations takes a crucial role in the development of biomedical materials. Rductive depolymerization after cellular uptake should then release the native substrates and minimize toxicity. Thus, in this proposal, the preparation of amino-rich polycations by using disulfide-exchange polymerization with various different functions of aminated monomers and sulfhydryl initiator (micromolecule, polysaccharide, polypeptide and protein) under the mildest conditions will be explored. Polycations further modified with targeting models. The effects of transfection efficiency, cell toxicity and synergistic therapy will be studied. Finally, a series of advanced biodegradable polycations with responsive, imaging, therapeutic and targeting functions will be developed. This proposal is expected to provide a new method for the designation of new generation of delivery carriers for biomedical applications.