Collaborative Research: Fate, Transport, and Organismal Uptake of Rod-Shaped Nanomaterials

目前，人们对刚性高各向异性纳米结构对环境的影响知之甚少。具有高纵横比（AR =长径比）的纳米棒是一种令人兴奋的纳米材料，具有许多潜在的应用前景。然而，到目前为止，只有有限数量的研究调查了这些细长纳米材料的环境命运。考虑到各向异性影响纳米棒与生物系统的相互作用，这一领域的工作缺乏尤其令人惊讶。推动当前努力的基本假设是，AR和表面化学的变化将改变决定纳米棒在河流系统中命运的机制和动力学。为了验证这一假设，pi已经制定了一项研究计划，该计划由四个高度相互关联的项目任务组成：在任务1中，我们将合成具有不同AR的金纳米棒，然后我们将使用一系列与环境相关的金属氧化物（例如SiO2， γ - fe2o3, CeO2）将其功能化，以获得一套具有形状和表面化学异质性的纳米材料。然后，这些纳米棒将用于评估纳米棒聚集（任务2）、纳米棒沉积（任务3）和过滤喂养双壳藻的吸收率（任务4）的研究中。完成每一项任务本身就是一项重要的工作；然而，我们已经制定了一个有凝聚力的研究计划，其中在任何一个任务中获得的知识都被用来帮助完善整体研究计划。智力优势：各向异性的纳米颗粒正在以不断扩大的各种形状和大小的数量不断增加。目前，人们对这些高度复杂的纳米材料对环境的影响知之甚少。本文提出的努力将为描述材料各向异性如何决定环境基质中纳米材料的命运提供基本基础。这项工作的预期智力成果是：i)系统地检查纳米棒聚集动力学和分形维数作为纵横比和溶液化学的函数；ii)通过柱研究中颗粒特性（AR，表面化学）和收集器参数（例如收集器尺寸和表面粗糙度）的系统变化来描述沉积机制；（iii）量化AR对无所不在的滤食性氟化c.f uminea吸收纳米材料的影响。虽然我们的重点是金和金核纳米棒，但所获得的结果有望转化为其他各向异性材料。更广泛的影响：对更广泛的影响制定了多维方法。这种方法利用了三个合作机构的现有项目，同时整合了各个小组的工作成果。研究、传播和外联。这些pi将通过弗吉尼亚州、南卡罗来纳州和伊利诺伊州现有的社区项目共同推广和传播研究成果。此外，该项目的成果将通过同行审查出版物和在有关会议上的介绍等传统途径向广大技术听众广播。推广工作将针对当地高中的少数民族学生。本科研究。所有三所合作院校将提供本科生研究机会。在他们的职业生涯中，这些pi在他们的实验室中共同支持了90多名本科生研究人员（其中很大一部分是历史上在科学和工程领域代表性不足的群体的成员），这一努力将为本科生提供更多的研究机会。本科和研究生教育。在这项工作中提出的研究将纳米材料合成和表征技术与胶体物理原理结合起来，以一种在本科化学或环境工程课程中不常见的方式。鉴于这一事实，所有三个pi将参与基于这项研究的课堂材料（例如，讲座，演示）的开发和制作，这些材料将被纳入所有三个机构的课程。

CBET 1336353There is currently very little known about the environmental implications of rigid highly anisotropic nanostructures. Nanorods possessing high aspect ratios (AR = length:diameter) are an exciting nanomaterial class with many potential applications. To date, however, only a limited number of studies have examined the environmental fate of these elongated nanomaterials. The lack of work in this area is particularly surprising given that it has been definitively shown that anisotropy affects how nanorods interact with biological systems. The underlying hypothesis driving the present effort is that changes in AR and surface chemistry will alter the mechanisms and kinetics dictating nanorod fate in riverine systems. To test this hypothesis the PIs have developed a research plan that consists of four highly inter-related project tasks: In Task 1 we will synthesize gold nanorods with varying AR and we will then functionalize them using a range of environmentally relevant metal oxides (e.g., SiO2, gamma-Fe2O3, CeO2) to obtain a suite of nanomaterials that exhibit both shape and surface chemical heterogeneity. These nanorods will then be used in studies to evaluate nanorod aggregation (Task 2), nanorod deposition (Task 3), and uptake by the filter feeding bivalve Corbicula fluminea (Task 4). Completion of each of these tasks is an important undertaking in its own right; however, we have developed a cohesive research plan in which the knowledge gained in any one task is used to help refine the overall research plan.Intellectual Merit :Anisotropic nanoparticles are being produced in an ever-expanding variety of shapes and sizes in ever-increasing quantities. Presently ery little is known about the environmental implications of these highly complex nanomaterials. The effort proposed herein will provide a fundamental basis for the description of how material anisotropy dictates nanomaterial fate in environmental matrices. The expected intellectual outcomes of this effort are i) systematic examination of nanorod aggregation kinetics and fractal dimension as a function of aspect ratio and solution chemistry (ii) delineation of deposition mechanisms by the systematic variation of particle properties (AR, surface chemistry) and collector parameters (e.g., collector size and surface roughness) in column studies; and (iii) quantification of the effects of AR on nanomaterial uptake by the ubiquitous filter feeder C. fluminea. Although our focus is on gold and gold-core nanorods, the results obtained are expected to be translatable to other anisotropic materials. Broader Impacts :A multi-dimensional approach to broader impacts has been developed. This approach leverages existing programs at the three collaborating institutions while working to integrate efforts across the groups. Research dissemination and outreach. The PIs will collectively promote and disseminate the research results through existing community programs in Virginia, South Carolina, and Illinois. In addition, the results of this project will be broadcast to a broad technical audience through the traditional pathways of peer-reviewed publications and presentations at relevant conferences. Outreach efforts will target minority students in local high schools. Undergraduate research. Undergraduate research opportunities will be made available at all three collaborating institutions. Over the course of their careers, the PIs have collectively supported over 90 undergraduate researchersin their laboratories (a significant percentage of whom are members of historically under-represented groups in science and engineering) and this effort will provide additional undergraduate research opportunities. Undergraduate and graduate education. The research proposed in this effort combines nanomaterial synthesis and characterization techniques with colloidal physical principles in a manner that is not routinely found in undergraduate chemistry or environmental engineering curricula. Given this fact, all three PIs will take part in the development and production of classroom material (e.g., lectures, demonstrations) based upon this research that will be incorporated into courses at all three institutions.