Interactions between engineered nanoparticles in aquatic systems: Roles of engineered capping agents and natural organic matter

新型纳米材料的快速发展及其在消费产品中的应用，与调查可能对环境造成的影响的努力不能相提并论。工程纳米颗粒(ENPs)的特性越来越多地通过使用有机封顶剂为特定应用量身定做。封顶剂所赋予的性质也可能影响这些材料在环境中的运输、毒性和命运。除了有目的地定制ENPs外，众所周知，地表水中普遍存在的天然有机物(NOM)将与天然胶体和ENPs相互作用，影响它们的环境行为。到目前为止，很少有研究集中于系统地研究工程封顶剂在控制ENPs环境行为中所起的作用。虽然初步研究集中在NOM和ENPs之间的相互作用，但关于控制这些相互作用的机制仍然存在许多问题。此外，现有的任何努力都没有试图将NOM-ENP相互作用的环境行为和机制与ENPs、NOM和水的化学成分的性质联系起来。随着数量惊人的新产品的开发，开发一个基于这些特性来预测环境行为的基本框架是至关重要的。智力价值：这项工作的首要目标是更好地理解合成封顶剂和NOM在控制水环境系统中ENPs的同质和异质聚集方面的作用。利用一套配体稳定的金纳米颗粒(AuNPs)和各种NOM分离物，该项目的具体目标是：(1)将封闭剂的物理化学性质与水生系统中被封顶的ENPs之间的相互作用联系起来；(2)将封闭剂和NOM的物理化学性质与水生系统中被封顶的ENPs和NOM之间的相互作用联系起来；(3)将封闭剂、NOM和悬浮颗粒物的物理化学性质与水生系统中被封顶的ENPs和悬浮颗粒物之间的相互作用联系起来。ENP关于同种聚集的稳定性将使用Zeta电位和使用时间分辨动态光散射测量的聚集速率来评估。NOM-AuNP相互作用将用荧光和表面增强拉曼光谱来探测。最后，金纳米粒子与悬浮胶体之间的相互作用将通过仪器中子活化分析的新应用来量化。通过使用一组特征良好的ENP，这些ENP只在表面功能上有所不同，环境行为可以与ENP性质在结构-活性类型关系中相关联。这项工作将提高基于NP特征预测环境命运的能力，并产生设计更安全的纳米材料所需的反馈。更广泛的影响：拟议的工作是变革性的，因为它旨在使该领域从以个案为基础评估纳米材料的环境影响，转向发展将环境行为与纳米颗粒特性相关联的结构-活性类型关系。预计这样的框架将扩展到其他类别的纳米颗粒和环境过程，如沉积、氧化还原和溶解。该项目带来的大量工作，无论是这个团队还是其他人，都很可能会促进改进的模型的开发，以预测环境命运和评估风险。这项工作支持安全纳米材料和纳米制造倡议的目标，国际和平协会是该倡议的成员，并将促进与俄亥俄州立大学和其他机构的同事的合作。其他更广泛的影响将来自环境工程博士生的教育所形成的人力资本。外联、本科生教育和本科生研究机会将是拟议工作的组成部分。PI有通过俄亥俄州立大学现有项目支持本科生研究的历史，这些项目侧重于招收女性和少数族裔学生。PI将继续通过在实验室接待高级项目团队、约翰逊学者(大学新生)和SESEY(高中)学生来指导本科生研究人员。这些学生将成为有关工作研究团队中不可或缺的一部分。此外，PI将开发一个侧重于水处理的颗粒过滤的教育模块，该模块适合K-12和工程专业新生，作为吸引学生参与环境工程领域的工具。

1067794NasonThe rapid development of novel nanomaterials and their incorporation into consumer products has not been paralleled with an equal effort investigating the possible environmental implications. Increasingly, the properties of engineered nanoparticles (ENPs) are tailored for specific applications through the use of organic capping agents. The properties imparted by the capping agents are also likely to influence the transport, toxicity and fate of these materials in the environment. In addition to the purposeful tailoring of ENPs, it is well established that natural organic matter (NOM), which is ubiquitous in surface water, will interact with natural colloids and ENPs, influencing their environmental behavior. To date, little research has focused on systematically investigating the roles that engineered capping agents play in controlling the environmental behavior of ENPs. Although preliminary studies have focused on the interactions between NOM and ENPs, many questions remain about the mechanisms controlling these interactions. Furthermore, none of the existing efforts have attempted to correlate environmental behavior and mechanisms of NOM-ENP interactions with the properties of the ENPs, NOM, and aqueous chemical composition. With the staggering number of new products being developed, it is essential that a fundamental framework be developed for predicting environmental behavior based on these properties. Intellectual Merit: The overarching objective of this work is to develop an improved understanding of the roles of synthetic capping agents and NOM in controlling the homogeneous and heterogeneous aggregation of ENPs in aquatic environmental systems. Using a suite of ligand-stabilized gold nanoparticles (AuNPs) and various NOM isolates, the specific aims of the project are to: (1) Correlate the physicochemical properties of capping agents with interactions between capped ENPs in aquatic systems; (2) Correlate the physicochemical properties of capping agents and NOM with interactions between capped ENPs and NOM in aquatic systems; and (3) Correlate the physicochemical properties of capping agents, NOM and suspended particulate matter with the interactions between capped ENPs and suspended particulates in aquatic systems. ENP stability with respect to homo-aggregation will be assessed using the zeta potential and aggregation rates measured using time-resolved dynamic light scattering. NOM-AuNP interactions will be probed using fluorescence and surface enhanced Raman spectroscopy. Finally, the interactions between AuNPs and suspended colloids will be quantified through a novel application of instrumental neutron activation analysis. By using a group of well-characterized ENPs that vary only with respect to their surface functionality, environmental behavior can be correlated with ENP properties in structure-activity type relationships. This work will provide an improved ability to predict environmental fate based on NP characteristics and yield the feedback necessary for the design of safer nanomaterials. Broader Impacts: The proposed work is transformational in that it aims to move the field away from assessing the environmental implications of nanomaterials on a case-by-case basis and towards the development of structure-activity type relationships correlating environmental behavior with nanoparticle characteristics. It is anticipated that such a framework will be extendable to other classes of nanoparticles and environmental processes like deposition, redox and dissolution. The larger body of work made possible by the project, both by this team and others, will likely facilitate the development of improved models for predicting environmental fate and assessing risk. The work supports the aims of the Safer Nanomaterials and Nanomanufacturing Initiative, of which the PI is a member, and will spur collaborations with colleagues at OSU and other institutions. Other broader impacts will result from the formation of human capital from the education of a Ph.D. student in environmental engineering. Outreach, undergraduate education and opportunities for undergraduate research will be an integral part of the proposed work. The PI has a history of supporting undergraduate research through existing programs at OSU that focus on the recruitment of women and minority students. The PI will continue to mentor undergraduate researchers through hosting senior project teams, Johnson scholars (college freshmen) and SESEY (high school) students in the laboratory. These students will become an integral part of the research team on the work in question. In addition, the PI will develop an educational module focused on particle filtration for water treatment that is appropriate for K-12 and freshmen engineering students as a tool for engaging students in the field of environmental engineering.