Statistical mechanics of polymer systems and lipid bilayer membranes

我的研究重点是复杂流体的结构和动力学性质，包括单链聚合物体系、朗缪尔单分子膜和脂质双层膜。这些聚合物体系在薄膜技术中具有实际应用，并具有环境应用，例如在土壤修复过程中使用生物膜(这与UPEI在生态毒理学方面的专业知识很好地联系在一起)。此外，这项研究具有重要的生物医学意义。例如，对分离聚合物在溶液中的盘绕-球体和球体-固体转变的研究对于深入了解控制蛋白质折叠过程的一些关键特征是必不可少的。我将使用不连续分子动力学(DMD)模拟来研究不同的参数，包括单体/溶剂尺寸比，对均聚和杂聚体系的崩溃和冻结转变的影响。例如，朗缪尔单分子层由沉积在空气/水界面的单层表面活性剂组成。当单分子层被压缩到超过平衡扩散压力时，单分子层可以通过许多不同的机制崩溃。我将研究溶剂的结构如何影响单分子层的稳定性，并试图阐明导致特定类型崩溃现象的驱动机制。这些研究对于理解肺表面活性物质单分子层的功能非常重要，因为这可能有助于揭示呼吸窘迫综合征的机制，呼吸窘迫综合征发生在早产儿的肺泡内没有足够的表面活性物质衬里。而脂筏是富含胆固醇的区域，由于横向相分离，在模型脂质双层和细胞膜中形成。对脂筏形成的研究与理解细胞内运输、免疫反应和突触传递等过程相关。在这个研究项目中，我将研究脂组成的不同如何影响脂-脂/脂-胆固醇和三元脂-脂-胆固醇系统的形状、大小和结构域的数量。

My research focuses on the structural and dynamical properties of complex fluids, including single-chain polymer systems, Langmuir monolayers, and lipid bilayer membranes.  These polymeric systems have practical applications in thin-film technology and have environmental applications, such as employing biofilms in soil remediation processes (which links well with UPEI's expertise in ecotoxicology).  Additionally, this research has vital biomedical implications.  For example, studies on the coil-globule and globule-solid transitions for isolated polymers in solution are essential to obtain insight into some of the key features that dominate the protein folding process.  In my proposed research, I will use discontinuous molecular dynamics (DMD) simulations to examine the effects of varying different parameters, including the monomer/solvent size ratio, on both the collapse and freezing transitions for homopolymer and heteropolymer systems.     Langmuir monolayers consist of a single layer of surfactants deposited at an air/water interface.  When a monolayer is compressed beyond the equilibrium spreading pressure, the monolayer can collapse through a number of different mechanisms.  In this proposal, I will study how the structure of the solvent affects the stability of the monolayer and attempt to elucidate the driving mechanisms responsible for particular types of collapse phenomena.  These studies are important in understanding the function of lung surfactant monolayers, since this could shed light into the mechanisms responsible for Respiratory Distress Syndrome, a condition occurring in pre-mature infants where there is insufficient surfactant lining the alveoli in the lungs.   Lipid rafts are cholesterol rich domains which form in model lipid bilayer and cell membranes due to lateral phase separation.  Studies on raft formation are relevant for understanding processes such as intracellular trafficking, immune response, and synaptic transmission. In this research project, I will investigate how differences in lipid composition affect the shape, size, and the number of domains for binary lipid-lipid/lipid-cholesterol and ternary lipid-lipid-cholesterol systems.