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

在所有的碳基纳米材料（如富勒烯、碳纳米管和石墨烯）中，石墨烯基纳米材料对人类和动物的细胞毒性最小；然而，与其他纳米材料一样，它们具有抗菌特性，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。抗菌污染物会严重阻碍天然微生物种群的功能，导致水中生物和化学废物的无效去除。由于石墨烯基产品的市场预计在2015年将达到6700万美元，到2020年将达到近6.75亿美元，预计将产生石墨烯基废物。污水处理厂将成为这些废物的最终储存库之一。因此，有必要了解这些石墨烯基纳米材料对负责废水处理的微生物种群的影响。目前，大多数关于石墨烯基纳米材料的毒理学研究都集中在实验室环境下石墨烯基纳米材料的单一成分对一种或两种细菌的影响上。很可能这些研究并没有反映出石墨烯基纳米材料对环境的真正影响。本研究的首要目标是了解石墨烯基纳米材料的微生物毒性机制，并确定影响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）中微生物群落功能的毒性浓度。智力优势：该项目将利用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，更好地解决这些纳米材料在环境质量、可持续性和安全性方面的挑战，从而实现纳米毒理学科学的变革性研究。这将是第一个利用分子生物学技术来评估石墨烯基纳米材料的毒性机制的研究，以回答传统毒理学分析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与DNA微阵列平台同时分析。同时，传统的环境工程技术将被用于设定石墨烯基纳米材料在环境中的可接受释放浓度限制。在这项研究中，我们将研究纯石墨烯基纳米材料和纳米复合材料对废水处理厂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，石墨烯基纳米材料用于“清洁”，具有几种微生物的良好控制系统对细菌有毒。然而，实际的水生系统比初步研究中使用的简化系统要复杂得多。在本项目中，将对真实水生系统条件下石墨烯基纳米材料对微生物群落及其生物地球化学循环的影响进行系统调查。更广泛的影响：该项目可能会影响石墨烯基纳米材料在各种技术中的使用和应用。这些结果将有助于决策者、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组成部分：(1)指导教师进行环境研究，这是最近由美国国家科学基金会资助的教师新研究体验（RET）计划的一部分，目的是让他们了解工程领域，并能够在这条道路上指导他们的学生；(2)开展试点项目，为8-12年级的女生提供暑期研究经验，以扩大理工科学生的多样性；(3)将环境工程、环境生物技术和微生物生态学纳入休斯敦大学环境工程本科和研究生课程。PI将她作为少数民族的经验带到了对代表性不足的学生的指导中。多样性不仅是一个目标，也是她研究小组的基石。PI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.