Interaction of Engineered Nanomaterials with Artificial Cell Membranes

在过去的五年里，人们对工程纳米材料的毒性这一与健康相关的问题越来越感兴趣。细胞有多种途径通过细胞膜摄取分子和颗粒来控制其内部环境，包括高选择性的膜蛋白和多肽以及蛋白质介导的内吞和吞噬作用。基于纳米颗粒(NP)的药物输送和分子成像应用将纳米颗粒输送到细胞内，通常使用促进特定信号和摄取的生化功能化。构成细胞膜的脂质双层被认为是离子和非功能化大分子不能穿透的，然而，流行病学研究表明，在某些条件下，非功能化的NPs可以通过被动的、非介导性的途径穿过或破坏细胞膜，导致急性细胞毒性和细胞死亡。非介导性的NP在细胞上的吸附和摄取尚不清楚。最近的研究集中在收集经验流行病学数据(例如，细胞对NP的摄取、对老鼠或鱼等生物的毒性)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，几乎不可能从这些测量过渡到详细了解导致非介导性NP摄取到细胞内和破坏双层的机制。需要评估纳米材料的生物利用度和毒性的量化措施，以便处理纳米技术对人类健康和环境的影响。智力价值：拟议工作的智力价值是理解工程纳米材料可以导致简化的模型细胞膜(即脂质双层)的破坏和被动运输的机制和条件。研究人员假设，在某些条件下，工程NPs可以被动地跨双层转移，并在双层中造成纳米级的缺陷，这在细胞毒性中发挥了作用。纳米颗粒和脂类双层之间的相互作用是独特的，因为颗粒和膜的长度尺度几乎相同。更广泛的影响：对NP和脂质双层之间相互作用的基本了解具有潜在的变革性，因为它可能：(1)提高我们对工程和环境NP的毒性的理解；(2)使合理设计用于药物输送和生物医学/分子成像的良性NP；(3)导致高通量毒性测试方案；以及(4)基于证据的纳米材料的监管和方案。将开发一个实验平台和方法，作为NP和脂质性质以及物理化学环境的函数，实时定量NP通过脂膜的转运。一种“自下而上”的方法将被用来增加双层的复杂性，通过掺入膜蛋白和糖脂来形成人工糖催化剂。工程纳米颗粒在很大程度上是不受监管的，因为NP的运输、命运和毒性还没有得到充分的评估。这项拟议的研究集中在工程纳米材料与脂类双层之间的相互作用，脂类双层可以说是生命和环境之间最重要的界面。这项建议涉及纳米技术的毒性，并对监管纳米技术的生产、分配和在医药、服装、化妆品等领域的应用产生重大影响。作为拟议工作的一部分，国际和平倡议旨在通过以下方式提高工程学和自然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)开发一门关于纳米技术的社会和伦理影响的跨名单研究生课程；(2)在华盛顿特区举办一期为期两周的学生讲习班，研究科学政策和文化。PI还将通过资助代表不足的本科生研究人员来加强他对本科生研究的坚定承诺。

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.