CAREER:Toxicology of graphene-based nanomaterials: A molecular biotechnology approach

在所有碳基纳米材料(如富勒烯、碳纳米管和石墨烯)中，石墨烯纳米材料已被证明对人类和动物的细胞毒性最小；然而，与其他纳米材料一样，它们具有抗菌性能，因此可能对废水处理产生严重影响。在污水处理厂，微生物负责通过消化有机物质和其他污染物来清洁水。抗微生物污染物会严重阻碍本地微生物种群的功能，导致无法有效地去除水中的生物和化学废物。由于基于石墨烯的产品的市场预计在2015年将达到6700万美元，到2020年将达到近6.75亿美元，因此预计将产生基于石墨烯的废物。废水处理厂将是这些废物的最终储存库之一。因此，了解这些基于石墨烯的纳米材料对负责废水处理的微生物种群的影响是至关重要的。目前，大多数基于石墨烯的纳米材料的毒理学研究都集中在实验室环境下单一组成的石墨烯纳米材料对一两个细菌的影响。这些研究很可能没有反映基于石墨烯的纳米材料对环境的真正影响。这项研究的总体目标是了解基于石墨烯的纳米材料的微生物毒性机制，并确定在废水处理中重要的各种生物地球化学循环(如氮、硫和碳循环)中影响微生物群落功能的毒性浓度。智力优势：该项目将通过使用一种将微生物生态学和环境生物技术领域与传统环境工程相结合的新方法，实现纳米毒理学的变革性研究，以更好地应对这些纳米材料在环境质量、可持续性和安全性方面的挑战。这将是第一次使用分子生物学技术来评估基于石墨烯的纳米材料的毒性机制，以回答传统毒理学检测无法回答的机制问题。此外，本研究还将使用分子生物技术方法来确定不同浓度的石墨烯基纳米材料对废水中不同营养循环的影响。使用这种方法，数千个基因和生物地球化学途径将通过DNA微阵列平台同时进行分析。同时，将利用传统的环境工程技术，为基于石墨烯的纳米材料在环境中设定可接受的释放浓度限制。在这项研究中，我们将调查纯形式和纳米复合形式的石墨烯基纳米材料对污水处理厂中的微生物及其生物地球化学循环的环境影响。PI进行的初步研究结果表明，以石墨烯为基础的纳米材料对细菌是有毒的，这些材料用于含有几种微生物的“干净”、控制良好的系统。然而，真实的水上系统比初步研究中使用的简化系统要复杂得多。在拟议的项目中，将进行一项系统的调查，以了解在真实的水系条件下，基于石墨烯的纳米材料对微生物群落及其生物地球化学循环的影响。广泛的影响：该项目可能会影响基于石墨烯的纳米材料在各种技术中的使用和应用。这些结果将有助于政策制定者、监管官员和环境科学家评估纳米材料风险所需的知识体系。然而，该项目最重要的影响之一是对年轻科学家和研究人员的教育和培训，他们将熟练地确定这些新材料在环境中的安全性。该项目包括三个教育和推广部分：(1)在环境研究方面对教师进行辅导，这是国家科学基金会最近资助的一个新的教师研究体验(RET)计划的一部分，目的是使他们能够了解工程领域，并能够在这一途径上指导他们的学生；(2)开发一项试点计划，为8-12年级的女孩提供暑期研究经验，以扩大科学和工程方面的多样性；(3)将环境工程、环境生物技术和微生物生态学纳入密歇根大学环境工程本科和研究生课程。国际学生联合会将她作为少数族裔的经验带到了对代表不足的学生的指导中。多样性不仅是她的目标，也是她研究小组的基石。国际和平研究所已经成功地聘请了三名女研究生进行研究，其中一名是西班牙裔美国博士生。

CBET 1150255-RodriguesAmong all the carbon-based nanomaterials (e.g., fullerenes, carbon nanotubes and graphene), graphene-based nanomaterials have been shown to be the least cytotoxic to humans and animals; however, like other nanomaterials, they have antimicrobial properties and may therefore have serious impacts on wastewater treatment. In wastewater treatment plants, microorganisms are responsible for cleaning the water by digesting organic materials and other contaminants. Antimicrobial pollutants can seriously hinder the functionality of the native microbial population, leading to ineffective removal of biological and chemical wastes in the water. Since the market for graphene-based products is projected to be as large as $67 million in 2015 and reach nearly $675 million by 2020, it is expected graphene-based wastes to be generated. Wastewater treatment plants will be one of the ultimate repositories for these wastes. Therefore, it is essential to understand the effect of these graphene-based nanomaterials on microbial populations responsible for the wastewater treatment. At this time, most toxicological studies with graphene-based nanomaterials have focused on the effects of single compositions of graphene-based nanomaterials on one or two bacteria in laboratory settings. It is likely that these studies do not reflect the real effects of graphene-based nanomaterials on the environment. The overarching goal of this research is to understand the mechanisms of microbial toxicity of graphene-based nanomaterials and determine the toxic concentrations that affect the functionality of microbial communities involved in various biogeochemical cycles important in wastewater treatment, such as nitrogen, sulfur, and carbon cycles.Intellectual Merit: This project will enable transformative research in nanotoxicological science by using a new approach that integrates the fields of microbial ecology and environmental biotechnology with traditional environmental engineering to better address challenges in environmental quality, sustainability and security of these nanomaterials. This will be the first study to employ molecular biology techniques to assess the mechanisms of toxicity of graphene-based nanomaterials to answer mechanistic questions that cannot be answered with traditional toxicological assays. Furthermore, this study will also use a molecular biotechnology approach to determine the effects of different concentrations of graphene-based nanomaterials on different nutrient cycles in wastewater. Using this approach, thousands of genes and biogeochemical pathways will be analyzed simultaneously with a DNA microarray platform. At the same time, traditional environmental engineering techniques will be used to set acceptable release concentration limits for graphene-based nanomaterials in the environment. In this study, we will investigate the environmental effects of pure and nanocomposite forms of graphene-based nanomaterials on microorganisms and their biogeochemical cycles in wastewater treatment plants. Results of preliminary studies conducted by the PI show that graphene-based nanomaterials for "clean," well-controlled systems with several microorganisms are toxic to bacteria. However, real aquatic systems are more complex than the simplified system used in the preliminary study. In the proposed project, a systematic investigation will be conducted to understand the impact of graphene-based nanomaterials on microbial communities and their biogeobiochemical cycles under real aquatic system conditions.Broader Impact: The project can potentially impact the use and applications of graphene-based nanomaterials in various technologies. The results will contribute to the body of knowledge required to assess the risk of nanomaterials by policy makers, regulatory officials, and environmental scientists. However, one of the most important impacts of this project is the education and training of young scientists and researchers who will be skilled to determine how safe these new materials are in the environment. This project includes three education and outreach components: (1) Mentoring of teachers in environmental research as part of a new research experience for teachers (RET) program recently funded by NSF in order to allow them to learn about the field of engineering and be able to mentor their students in this path; (2) Development of a pilot program to provide summer research experiences to girls in Grades 8-12 to expand diversity in science and engineering; (3) Integration of environmental engineering, environmental biotechnology, and microbial ecology into the environmental engineering undergraduate and graduate curriculum at UH. The PI brings her experiences as a minority to the mentoring of under-represented students. Diversity is not only a goal, but a cornerstone of her research group. The PI has successfully engaged three female graduate students in research, one of which is Hispanic-American Ph.D. student.