生物可降解超支化聚合物的研究进展

Recent Advances of Biodegradable Hyperbranched Polymers

近年来,随着聚合物材料和生物医药交叉领域的发展,生物可降解聚合物得到了广泛关注.其中,生物可降解超支化聚合物具有独特的三维拓扑结构、大的内部空腔、众多的活性末端基团以及良好生物相容性和可降解性等特点,在生物医学领域包括药物/造影剂输送、基因转染、蛋白质纯化/检测/输送、抗菌、组织工程等领域都展现出很大的应用前景.本文主要从水解、酶解和刺激降解的降解机理出发,详细综述了近年来生物可降解超支化聚合物的研究进展,并简单介绍了它们在疾病治疗中的应用.

Hyperbranched polymers（HBPs） are highly branched macromolecules with a three-dimensional dendritic architecture. They have four important characteristics：（1） their three-dimensional dendritic architecture can prevent entanglement among polymer chains, thereby resulting in completely different properties from linear polymers;（2） their adequate spatial cavities are beneficial to encapsulate guest molecules;（3） their good solubility and low viscosity can improve processability in comparison with linear polymers;（4） there is a large population of terminal functional groups in HBPs that are easy to for chemical modification. Due to these unique topological structures and distinct physical/chemical properties, HBPs and their assemblies have exhibited great potential in various biomedical areas including drug/contrast agent delivery, gene transfection, protein purification/detection/ delivery, antibacterial materials and tissue engineering. The advances of HBPs in biomedical applications have led to an accelerated discovery of HBPs with biodegradable backbones. In recent years, the biodegradable HBPs with excellent biocompatibility, defined structure, and controlled degradation profiles have become increasingly important in therapeutic applications owing to their low toxicity, non-immunogenicity as well as general ease of degradation and metabolization. Up to now, a large number of biodegradable HBPs have been well designed and widely used in therapeutic applications, such as hyperbranched polyester, hyperbranched polyphosphate, hyperbranched polysaccharide, and hyperbranched polypeptide. On the other hand, in order to further study the biodegradable HBPs, a detailed summary and comprehensive understanding on the biodegradable mechanisms of HBPs might be helpful. Considering the differences of degradation reactions, we grouped the biodegradable mechanisms into three types： hydrolysis, enzymolysis and stimuli-responsive degradation. To date, although many elegant reviews on HBPs have been published, a systematic review on the biodegradable HBPs focused on the degradation mechanisms has not been reported so far. Herein, the recent advances of biodegradable HBPs are highlighted. In particular, the biodegradable mechanisms of HBPs, including hydrolysis, enzymolysis and stimuli-responsive degradation, are emphasized. Finally, the applications in disease treatment and possible future directions in this emerging area are also briefly discussed.