Career Program: Molecular Design of Surface Modified Vesicles and Liposomes: A Theoretical Study

9624268 Szleifer囊泡和脂质体是由球状封闭的两亲分子双层形成的聚集体。脂质体在其核心中溶解大量分子的能力及其在水环境中的溶解度使其成为药物输送的理想系统。近年来，人们发现将聚合物接枝到脂质体表面可以延长这些聚集体在血液中的寿命。此外，通过用对特定细胞受体具有较大亲和力的分子对接枝的聚合物自由端基进行化学修饰，脂质体可用于靶向递送。尽管聚合物修饰脂质体作为主要的药物载体具有重要意义，但对控制其稳定性、寿命和靶向特定细胞的能力的因素还没有系统的了解。对接枝聚合物修饰的脂质体和囊泡的行为进行了系统的理论研究。单链平均场理论将用于研究组成聚集体的链分子（表面活性剂和聚合物）的行为。与实验测量相比，这种方法提供了准确的构象和热力学信息。这项工作的目的是系统地研究在哪些条件下改性聚集体可以实现寿命，热力学稳定性和特异性靶向。这项工作包括寻找表面活性剂（或脂质）、胆固醇和聚合物的成分，这些成分将在一定尺寸范围内形成稳定的囊泡，最适合药物输送。接枝链防止蛋白质在囊泡表面吸附的能力将被研究。特定的聚合物链结合了防止蛋白质吸附的能力和增强载体靶向特定细胞的构象特性。对聚合物修饰囊泡行为的微观理解将有助于开发新型聚集体，用于分离过程的试剂，如蛋白质分离和水介质中小疏水分子的增溶。理论研究将与三个实验组密切合作进行，他们正在研究：1)末端功能化聚合物修饰脂质体用于靶向药物递送；2)化学修饰囊泡诱导的囊泡膜融合；3)聚合物修饰表面上的蛋白质吸附。教学计划分为两部分。一种描述了在正式课堂教学中采用的方法。另一部分则展示了超出正式教学要求的不同项目。前者的基本思想是向学生提供物理过程、数学工具和实验测量之间的联系。理解这种关系可以使学生快速掌握基于先前所学科目的新概念。将开展的非正式活动包括专题讨论、讲座和对物理化学一般领域的具体应用感兴趣的本科生的研究。这些活动将仅限于选定的一小群学生；其目的是提供个性化的关注，这在大型正式课程中通常是无法获得的。此外，教案还包括本科生和研究生的专题研究项目。＊＊＊

9624268 Szleifer Vesicles and liposomes are aggregates formed by spherically closed bilayers of amphiphilic molecules. The ability of the lipsome to dissolve large quantities of molecules in their core and its solubility in aqueous environments makes them ideal systems for drug delivery. In recent years it was found that grafting polymers to the surface of the liposomes increases the longevity of these aggregates in the blood stream. Furthermore, by chemically modifying the grafted polymer free end-group with molecules that have large affinities to specific cell receptors, the liposomes can be used for targeted delivery. Despite the importance of polymer-modified liposomes as premier drug carriers, there is no systematic understanding of the factors that govern their stability, longevity, and ability to target specific cells. A systematic theoretical study of the behavior of liposomes and vesicles modified by grafted polymer chairs will be performed. The single-chain mean-field theory will be used to study the behavior of the chain molecules (surfactants and polymers) that comprise the aggregates. This approach provides accurate conformational and thermodynamic information as compared with experimental measurements. The aim of the work is to systematically study the conditions under which modified aggregates can achieve longevity, thermodynamic stability and specific targeting. The work consists of finding the compositions of surfactants ( or lipids), cholesterol and polymer that will form stable vesicles within a range of size that is optimal for drug delivery. The ability of the grafted chains to prevent protein adsorption on the surface of the vesicles will be studied. Specific polymer chains that combine the ability to prevent protein adsorption with conformational properties that enhance targeting of the carrier to specific cells. The microscopic understanding of the behavior of polymer modified vesicles that will be achieved should able the development of new types of ag gregates for use as reagents that can be used in separation processes, such as protein separation and solubilization of small hydrophobic molecules in aqueous media. Theoretical studies will be carried out in close collaboration with three experimental groups that are investigating: 1) the use of end-functionalized polymer-modified liposomes for targeted drug delivery, 2) vesicle-membrane fusion induced by chemical modification of the vesicle and 3) protein adsorption on polymer-modified surfaces. The teaching plan is divided into two parts. One describes the approach to be taken in formal classroom teaching. The other presents the different projects that go beyond the formal teaching requirements. In the former, the basic idea is to provide the students with the links between physical processes, mathematical tools and experimental measurements. Understanding this relationship enables students to quickly grasp new concepts based on previously learned subjects. The informal activities that will be undertaken include special topic discussions, lectures and research for undergraduate students interested in specific applications of the general field of physical chemistry. These activities will be confined to select small groups of students; the aim being to provide the personalized attention that is not generally available in large formal classes. Furthermore, the teaching plan also includes special topic research projects for undergraduate and graduate students. ***