CYCLODEXTRIN-CATALYZED EXCHANGE TO CONTROL LIPID COMPOSITION AND LIPID ASYMMETRY: FROM LIPOSOMES TO CELLS

非技术部分：活细胞被脂质（专门的脂肪分子）和蛋白质组成的薄膜包围。人工膜囊泡，称为脂质体，由膜脂质和蛋白质组成，形成类似于细胞膜的包膜。天然膜具有两层脂质，并且就组成而言是不对称的，在形成膜的两个脂质层中的每一个中具有不同类型的脂质。 但人工脂质体应用的一个关键限制是它们缺乏脂质不对称性。PI和团队的早期研究发现了一种制备不对称脂质体的新方法。本项目的重点将是发展材料科学的基本理解，用各种非天然脂质制备不对称脂质体，然后比较它们的功能特性。利用从拟议的材料研究中获得的知识，该项目还将确定如何调整开发的方法来改变生物细胞中的脂质，这将使来自天然细胞膜的生物材料用于递送分子和其他应用的应用成为可能。关于更广泛的影响，该项目将对未来科学家的职业发展产生重大影响，包括来自代表性不足群体的学生，通过培训研究生和本科生（包括通过与其他当地机构的联系）进行研究，实验原理和膜研究中使用的专业实验技术。学生还将接受科学研究和科学写作和口语的适当行为的培训。这将反过来为他们的专业成长和研究，教学和相关领域的职业生涯做好准备。技术部分：脂质不对称性，生物膜内外小叶（单层）脂质组成的差异，是许多细胞膜的重要特性。含有脂质双层的人工囊泡（脂质体）是已被证明是生物膜的宝贵模型的生物材料，并且可能用于许多应用中，但是缺乏制备具有不对称脂质分布的脂质体的方法限制了它们的实用性。该项目涉及开发新的方法，在开发不对称囊泡使用改性环糊精。第一个目标是制备仅在其内部或外部单层中含有非天然和带正电荷的阳离子脂质或聚乙二醇衍生的脂质的不对称脂质体。含有这些脂质的脂质体可用于将生物分子和药物递送到细胞中，从而可以改变细胞特性或基因表达。通过将这些非天然脂质限制在两个脂质层中的仅一个，这些研究将通过将它们捕获在脂质体中来最大化可以递送到细胞中的分子的量，并定制这些脂质体以最大化与生物系统的相互作用和相容性。第二个目标是将这些研究扩展到生物细胞。允许细胞质膜外层脂质置换的条件，以及这如何改变膜的物理结构和膜的完整性，将被定义。这将使得以天然膜为起点的新型生物材料的制备成为可能。在这些研究中，学生将接受用于研究膜蛋白和脂质的各种生化和光谱技术的专门培训，包括新开发的方法。学生还将接受科学研究的适当进行以及写作技能和口语技能的培训。这将为他们在生物/生物物理研究和/或教学领域的职业生涯做好准备。该项目将广泛影响膜生物学领域，包括药物输送和纳米材料应用。

Non-Technical Section: Living cells are surrounded by a thin membrane composed of lipids (specialized fat molecules) and proteins. Artificial membrane vesicles, called liposomes, are composed of membrane lipids and proteins which form an envelope similar to a cell membrane. Natural membranes have two layers of lipids and are asymmetric in terms of composition with different types of lipids in each of the two lipid layers that form the membrane. But a key limitation in the utility of artificial liposomes has been their lack of lipid asymmetry. Earlier studies by the PI and group discovered a novel method on how to prepare asymmetric liposomes. The focus of this project will be in developing a basic understanding of materials sciences in the preparation of the asymmetric liposomes with a variety of unnatural lipids, and then compare their functional properties. With the knowledge gained from the proposed materials research, this project also will define of how to adapt the methods developed to change the lipids in biological cells, which should enable applications in which biomaterials derived from natural cell membranes are used to delivery molecules and other applications. With respect to broader impacts, this project will have a strong impact on career development of future scientists, including students from underrepresented groups, by training graduate and undergraduate students (including via contacts with other local institutions) in the conduct of research, experimental principles, and the specialized experimental techniques used in membrane research. Students will also be trained in proper conduct of scientific studies and scientific writing and speaking. This will in turn prepare them for their professional growth and careers in research, teaching and allied fields.Technical Section: Lipid asymmetry, a difference in the lipid composition in the inner and outer leaflets (monolayers) of a biological membrane, is a crucial property of many cell membranes. Artificial vesicles (liposomes) containing lipid bilayers are biomaterials that have proven invaluable models of biological membranes, and possible use in a number of applications, but a lack of methods to prepare liposomes with asymmetric lipid distributions has limited their utility. This project involves developing novel methods in developing asymmetric vesicles using modified cyclodextrins. The first goal will to prepare asymmetric liposomes containing unnatural and positively charged cationic lipids or polyethylene glycol derivized-lipids in only their inner or outer monolayers. Liposomes containing these lipids have applications in delivery of biomolecules and drugs into cells that in turn could modify cell properties or gene expression. By restricting these unnatural lipids to only one of the two lipid layers, these studies will maximize the amount of molecules that can be delivered into cells by trapping them within liposomes, and tailoring these liposomes to maximize interactions and compatibility with biological systems. The second goal involves extending these studies to biological cells. Conditions allowing replacement of the lipids in the outer layer of cell plasma membranes, and how this alters membrane physical structure and membrane integrity, will be defined. This will enable the preparation of novel biomaterials having natural membranes as their starting point. In these studies, students will receive specialized training in a variety of biochemical and spectroscopic techniques used to study membrane proteins and lipids, including newly developed methods. Students will also be trained in proper conduct of scientific studies, and writing skills and speaking skills. This will prepare them for careers in field of biological/biophysical research and/or teaching. This project should broadly impact the field of membrane biology, including drug delivery and nanomaterial applications.