Nanoscale Engineering of LDL-Retentive Substrates

心血管疾病每年在美国成年人中造成惊人的伤亡。与脂质异常积聚相关的两种重要血管病变是动脉粥样硬化(低密度脂蛋白(LDL)积聚导致的动脉硬化)和大血管疾病，通常与胰岛素抵抗糖尿病有关，每年全球有100万人死于糖尿病。许多研究都是针对减轻脂代谢紊乱的药物的分子设计进行的。然而，这类药物可能对肝脏和肾脏有毒，无法全面治疗脂蛋白运输和滞留动力学，特别是在外周血管部位。因此，治疗脂质相关血管疾病的综合方法可能涉及使用调节脂质代谢的分子，以及适当亲脂蛋白并作为多功能载体处理运输中的脂蛋白的分子。最终，这种载体可以被改造成：(A)从大分子储存库中隔离脂蛋白，如增强动脉粥样硬化倾向的蛋白多糖；(B)减少脂蛋白氧化(导致巨噬细胞不受控制地摄取低密度脂蛋白，将其转化为泡沫细胞，成为动脉粥样硬化的前驱细胞)；以及(C)加强脂蛋白的运输和轻度氧化的脂蛋白的清除(通过巨噬细胞和肝脏)。然而，为了设计这样的载体，了解脂蛋白保留载体底物的化学和几何决定因素是必要的。这项提议描述了一项针对这一目标的主要研究计划。血管内膜的蛋白多糖是巨大的负电荷分子，呈现多聚糖胺多聚糖链(GAG)，可以协同招募低密度脂蛋白，并促进低密度脂蛋白的过度氧化，从而在动脉粥样硬化期间导致泡沫细胞的形成。作为低密度脂蛋白保留的竞争策略，研究人员建议设计新的可扩散的纳米级载体，能够呈现模拟呕吐的化学物质，并以高亲和力保留低密度脂蛋白。为此，将解决两个重要的问题：(A)模拟呕吐的化学和模型底物的纳米级形貌能否被设计成协同招募氧化型低密度脂蛋白？(B)如何将(A)中的见解应用于使用移动纳米载体保留低密度脂蛋白？为了解决(A)，研究人员将从理论上模拟和实验探索固定的金纳米颗粒(测试各种化学物质的低密度脂蛋白反应性的模型底物)和金/氧化锌纳米管的底物阵列的能力。官能化的烷硫醇在带负电荷的基团(-COOH，-OSO3H)中终止，以隔离低密度脂蛋白。假设是，在足够高的密度下，在提供柱间协同作用的地形底物构型中，这种化学作用可以通过低密度脂蛋白的载脂蛋白B-100中带正电荷的氨基酸残基静电隔离低密度脂蛋白。为了解决(B)，研究人员将探索使用聚合物树枝状大分子-类似于超支化的纳米载体来呈现(A)中观察到的最低密度脂蛋白保留化学物质，在各种纳米结构配置中，即通过系统地操纵脂蛋白分子诱饵的价态、分支和拴系。

0201788MogheCardiovascular disease takes a staggering toll of casualties among adult Americans each year. Two of the significant vascular pathologies related to the abnormal accumulation of lipids are atherosclerosis (the hardening of arteries due to build-up of low density lipoproteins (LDL)), and macrovascular disease, typically correlated with insulin resistant diabetes, which claims a million lives each year globally. Much research has been directed at the molecular design of drugs to alleviate the disorders of lipid metabolism. However, such drugs can be toxic to the liver and kidneys, and fail to comprehensively treat lipoprotein transport and retention dynamics, particularly at peripheral vascular sites. Thus, a comprehensive approach to treating lipid-related vascular disease could involve use of molecules regulating lipid metabolism as well as molecules that are suitably lipoprotein-philic and serve as multifunctional carriers for processing lipoproteins in transit. Ultimately, such carriers could be engineered to (a) sequester lipoproteins from macromolecular depots such as proteoglycans that heighten atherogenic tendencies; (b) reduce lipoprotein oxidation (which leads to unregulated uptake of LDL by macrophages, transforming them into foam cells, the precursors to atherosclerosis); and (c) enhance lipoprotein transport and clearance of mildly oxidized lipoproteins (via macrophages, and the liver). However, to engineer such carriers, an understanding of the chemical and geometric determinants of lipoprotein-retentive carrier substrates is necessary. This proposal describes a major research initiative toward this goal.The proteoglycans of the vascular intima are bulky, negatively charged molecules that present multimeric glycosaminoglycan (GAG) chains, which can co-operatively recruit low density lipoproteins, and encourage LDL hyperoxidation, which leads to foam cell formation during atherosclerosis. As a competitive strategy for LDL retention, the investigators propose to design novel diffusible, nanoscale carriers that can present GAG-mimetic chemistry and retain LDL with high affinity. To this end, two significant questions will be addressed: (a) Can the GAG-mimetic chemistry and nanoscale topography of model substrates be designed to synergistically recruit oxidized low density lipoproteins? (b) How can the insights derived in (a) be applied toward the use of mobile nanocarriers for LDL retention?To address (a), the investigators will theoretically simulate and experimentally explore the ability of immobilized gold nanoparticles (model substrates to test the LDL-reactivity of various chemistries) and substrate arravs of gold/ZnO nanopillars. functionalized with alkanethiols terminating in negatively charged groups (-COOH, -OSO3H), to sequester LDL. The hypothesis is that at adequately high densities, and in topographic substrate configurations affording inter-pillar cooperativity, such chemistries can electrostatically sequester LDL through the positively charged aminoacid residues from the apolipoprotein B-100 of the LDL. To address (b), the investigators will explore the use of polymeric dendrimer-Iike hyperbranched nanocarriers to present the most LDL-retentive chemistry observed in (a), in various nanoarchitectural configurations, that is, by systematically manipulating the valency, branching, and tethering of the molecular bait for the lipoprotein.