Versatile Polymeric Biomaterials

天然化合物的使用有助于提高高分子生物材料的生物相容性和生物接受度。结合细胞识别的信号剂对这类材料具有重要意义。我们计划设计、合成和表征含有部分天然生物化合物（如胆汁酸和糖类）的新聚合物，并对其预期应用进行测试。低聚糖单位通常在细胞膜中充当细胞识别的信号剂。含有悬垂糖基的合成糖共聚物可在生物和生物医学应用中用作多价天然寡糖模拟物，例如大分子药物和药物递送系统。我们打算系统地探索用于细胞相互作用和靶向药物递送的糖残基糖共聚物的使用。活性自由基聚合方法将被用于制造嵌段共聚物，在更疏水的嵌段中含有胆汁酸单元，在第二嵌段中含有糖残基，如氨基葡萄糖衍生物。这些聚合物的性质将被研究和优化，以适应其预期的应用。我们已经用阴离子聚合法制备了嵌段共聚物，并希望将其应用范围扩大到制造各种星形共聚物和低聚物，然后通过连接乙二醇残基/低聚糖使端基或侧基功能化，用于细胞识别。在这种情况下，我们计划使用主要胆汁酸之一的胆酸作为核心引发聚合，并改变嵌段的长度，以获得具有平衡两亲性的共聚物。这些聚合物有望对温度、pH值和离子强度的变化具有响应性，并可作为生物传感器和药物输送载体进行测试。我们将继续探索脂肪酶等酶在制备可降解聚合物中的应用，通过熵驱动开环聚合从天然化合物中提取的大环单体。酶的使用可以取代基于重金属的催化剂的使用，使聚合物摆脱残留的金属，从而使它们更具生物相容性。这种聚合物被认为是有用的形状记忆材料。我们最近发现的这种聚合物的多形状记忆效应将进一步研究，以优化聚合物的分子设计，并了解结构-性能关系。这项研究工作将有助于建立一个适用于组织工程、生物分离、生物传感和药物传递的新材料库。新聚合物的表征和物理化学研究应提供与其化学结构和组成相关的材料性质的理解。一些材料的生物相容性将被测试。这些材料将根据其预期应用进行测试和优化。我们期望得到的结果对高分子化学和材料科学的基础和实际方面都是有用和重要的。提议的工作的跨学科性质提供了一个理想的训练环境，为学生在化学和生物材料。

The use of natural compounds can help to improve the biocompatibility and bioacceptance of polymeric biomaterials in their applications. Conjugating signaling agents for cellular recognition is of importance for such materials. We plan to design, synthesize and characterize new polymers containing moieties of natural biocompounds such as bile acids and saccharides and test them for their intended applications. Oligosaccharide units often serve as signaling agents in cellular membrane for the recognition of cells. Synthetic glycopolymers containing pendant saccharide moieties may be used as multivalent natural oligosaccharide mimics in biological and biomedical applications such as macromolecular drugs and drug delivery systems. We intend to systematically explore the use of glycopolymers with sugar residues designed for cellular interactions and targeted drug delivery. Living radical polymerization methods will be used to make block copolymers with bile acid unit in the more hydrophobic block and with sugar residues such as derivatives of glucosamine in the second block. The properties of such polymers will be studied and optimized for their intended applications.We have used anionic polymerization method to make block copolymers and would like to expand its use to make a variety of star-shaped copolymers and oligomers followed by functionalization of the end groups or the side groups by attaching glycol-residues/oligosaccharides for use in cellular recognition. In this case, we plan to use cholic acid, one of the major bile acids, as the core to initiate the polymerization and vary the length of the blocks to obtain copolymers with balanced amphiphilic properties. These polymers are expected to possess responsiveness to changes in temperature, pH and ionic strength and may be tested for use as biosensors and drug delivery vehicles.We would continue to explore the use of enzymes such as lipases in the preparation of degradable polymers through entropy-drive ring-opening polymerization of macrocyclic monomers derived from natural compounds. The use of enzymes can replace the use of catalysts based on heavy metals, ridding the polymers free of residual metals and thus making them more biocompatible. The polymers are known to be useful as shape-memory materials. Our recent discovery of the multiple-shape memory effect of such polymers will be further studied to optimize the molecular design of the polymers and to understand the structure-property relationship.This research work will help to build a library of new materials suitable for use in tissue engineering, bioseparation, biosensing and drug delivery. The characterization and physico-chemical study of the new polymers should provide an understanding of the properties of materials related to their chemical structures and compositions. The biocompatibility of some of the materials will be tested. The materials will be tested and optimized for their intended applications. We expect that the results obtained are useful and important to both fundamental and practical aspects of polymer chemistry and materials science. The interdisciplinary nature of the proposed work provides an ideal training environment for students in chemistry and biomaterials.