Interaction of Engineered Nanomaterials with Artificial Cell Membranes

0932885波斯纳在过去的五年里，人们对工程纳米材料毒性的健康相关问题越来越感兴趣。细胞具有通过其细胞膜摄取分子和颗粒以控制其内部环境的各种途径，包括高度选择性的膜蛋白和肽以及蛋白质介导的内吞作用和吞噬作用。 基于纳米颗粒（NP）的药物递送和将NP递送到细胞中的分子成像应用通常使用促进特异性信号传导和摄取的生化功能化。 组成细胞膜的脂质双层被认为是离子和未官能化的大分子不可穿透的，然而，流行病学研究表明，在某些条件下，未官能化的NP可以通过被动的、非介导的途径穿过或破坏细胞膜，引起急性细胞毒性和细胞死亡。 对非介导的NP吸附到细胞上和摄取到细胞中知之甚少。 最近的研究集中在收集经验流行病学数据（例如细胞对NP的吸收，对生物体如大鼠或鱼类的毒性）或精确的NP表征（例如大小，形状，聚集程度，电荷和表面化学）。 然而，这是几乎不可能从这些测量过渡到详细了解的机制，负责非介导的NP吸收到细胞和破坏的双层。 需要对纳米材料的生物利用度和毒性进行定量评估，以便解决纳米技术对人类健康和环境的影响。 智力优势：拟议工作的智力价值是了解工程纳米材料可能导致简化模型细胞膜（即脂质双层）中断和被动转运的机制和条件。 研究人员假设，在某些条件下，工程化的纳米颗粒可以被动地跨双层易位，并在双层中引起纳米级缺陷，这在细胞毒性中起作用。 纳米颗粒和脂质双层的相互作用是独特的，因为颗粒和膜具有几乎相同的长度尺度。更广泛的影响：对NP和脂质双层之间相互作用的基本理解具有潜在的变革性，因为它可以：（1）提高我们对工程和环境NP毒性的理解;（2）合理设计用于药物和生物医学/分子成像的良性NP;（3）产生高通量毒性测试方案;（4）基于证据的纳米材料监管和方案。 将开发一个实验平台和方法，用于在真实的时间内定量NP通过脂质膜的转运，作为NP和脂质性质以及物理化学环境的函数。 一个“自下而上”的方法将被用来增加的膜蛋白以及糖脂的结合，形成人工glycocalyx.Engineered纳米粒子的双层的复杂性，在很大程度上是不受管制的，因为运输，命运，和毒性的NP没有得到充分的评估。拟议的研究重点是工程纳米材料与脂质双层的相互作用，可以说是生命与环境之间最重要的界面。 该提案涉及NP毒性，并对NP生产，分配和在医药，服装，化妆品等中的应用的监管具有强烈的影响，作为拟议工作的一个组成部分，PI旨在通过以下方式提高工程和物理科学研究生对纳米科学和技术的社会和伦理影响的认识：（1）开发一个交叉列出的研究生水平课程的社会和伦理影响的纳米技术;和（2）组织一个为期两周的学生研讨会在华盛顿，DC审查科学政策和文化。 PI还将通过资助代表性不足的本科研究人员来建立他对本科研究的坚定承诺。

0932885PosnerOver the past five years, there has been a growing interest in the health-related issue of toxicity of engineered nanomaterials. Cells have various routes for uptake of molecules and particles through their cell membranes to control their internal environment including highly selective membrane proteins and peptides as well as protein mediated endocytosis and phagocytosis. Nano-particle (NP) based drug delivery and molecular imaging applications that deliver NP into cells typically use biochemical functionalization which promote specific signaling and uptake. The lipid bilayers that make up cellular membranes are believed to be impenetrable to ions and unfunctionalized macromolecules, however, epidemiological studies have shown that unfunctionalized NPs can, under some conditions, cross or disrupt the cell membrane through passive, unmediated routes causing acute cellular toxicity and cell death. The unmediated NP adsorption onto and the uptake into cells is poorly understood. Recent research focuses on either collection of empirical epidemiological data (e.g. uptake of NP by cells, toxicity to organisms such as rats or fish) or precise NP characterization (e.g. size, shape, degree of aggregation, charge, and surface chemistry). However, it is almost impossible to transition from these measurements to detailed understanding of the mechanisms responsible for unmediated NP uptake into cells and disruption of the bilayer. Quantitative measures of nanomaterial bioavailability and toxicity need to be assessed so that the impact of nanotechnology on human health and the environment can be addressed. Intellectual Merit: The intellectual merit of the proposed work is to understand the mechanisms and conditions under which engineered nanomaterials can cause disruption of, and passive transport through, simplified model cell membranes, namely lipid bilayers. The,investigators hypothesize that under some conditions engineered NPs can passively translocate across, and cause nanoscale defects in, bilayers which plays a role in cellular toxicity. The interaction of nanoparticles and lipid bilayers are unique because the particle and membranes have nearly the same length scale. Broader impact: Fundamental understanding of the interaction between NP and lipid bilayers is potentially transformative because it may: (1) improve our understanding of toxicity of engineered and environmental NP; (2) enable rational design of benign NP for delivery of drugs and biomedical/molecular imaging; (3) result in high-throughput toxicity testing protocols; and (4) evidence-based regulation and protocols of nanomaterials. An experimental platform and methods will be developed for quantifying the NP transport through lipid membranes in real time as a function of the NP and lipid properties and the physicochemical environment. A "bottom-up" approach will be employed to increase the complexity of the bilayer through incorporation of membrane proteins as well as glycolipids to form an artificial glycocalyx.Engineered nanoparticles are largely unregulated because the transport, fate, and toxicity of NP have not been adequately assessed. The proposed research focuses on the interactions of engineered nanomaterials with lipid bilayers, arguably the most important interface between life and the environment. This proposal addresses NP toxicity and has strong implications on the regulation of NP production, distribution, and application in medicine, clothing, cosmetics, etc. As an integral part of the proposed work, the PI aims to increase engineering and physical science graduate students' awareness of the societal and ethical implications of nano science and technology through: (1) development of a cross-listed graduate level course on the societal and ethical implications of nanotechnology; and (2) organization of a two week student workshop in Washington, DC which examines scientific policy and culture. The PI will also build upon his strong commitment to undergraduate research by funding underrepresented undergraduate researchers.