C60 Biotransformation and Bioaccumulation: Environmental Impact Implications

快速的工业规模生产，加上独特的材料性能，支撑了人们对工程纳米级材料无意中影响自然系统健康和功能的日益关注。碳基纳米级材料，特别是富勒烯和纳米管，已被提出用于各种应用，并有望在工业规模上生产。建立对自然和工程系统中材料行为的基本定量理解，可以实现准确的预测行为模型，这对于降低风险和可持续发展所必需的材料生命周期评估至关重要。特别令人感兴趣的是这些材料可能相互作用的生物界面，因为富勒烯的生物介导转化可能显著影响它们的移动性、生物利用度、反应性、毒性和整体环境影响。然而，到目前为止，还没有对富勒烯生物转化进行系统的评估。他们将寻求评估水可用富勒烯物种对生化转化的敏感性及其生物学意义。具体来说，他们将：(1)通过部分使用放射性标记的P14PCB60B来表征生物转化的速率和副产物，(2)确定生物转化如何影响CB60B的毒性，(3)通过模型蚯蚓系统量化P14PCB60B及其副产物的生物利用度和生物积累潜力。他们将测试以下假设：1)CB60B可以被非特异性酶系统氧化，如锰过氧化物酶，它通过自由基（OH）攻击参与复杂碳大分子的降解，和/或由纤维素酶真菌或细菌产生的其他酶降解顽固化合物；(2)这种生物转化会降低CB60B的毒性和生物蓄积潜力，但可能会增加其溶解度和生物利用度。使用化学上独特的CB60B，具有不同的同位素特征，生物转化研究将在无细胞（例如，催化非特异性自由基（OH）氧化的纯化锰过氧化物酶）、全细胞、纤维素水解真菌的体内培养、降解多环芳烃的混合培养和降解多环芳烃的纯培养中进行。反应动力学和产物将通过一系列分析（放射色谱（HPLC）， P13PC-NMR, MALDI-MS, UV/Vis，闪烁计数等）进行表征。相应的毒性研究将测量暴露于可用的CB60B和生物转化衍生物之前和之后的微生物异养活性。C60及其衍生物的生物积累和可利用性将通过整个生物体（模型蚯蚓系统）和仿生吸附剂实验进行评估，类似于先前对多芳烃的研究。这项工作响应了环境倡导团体、新兴纳米技术产业和监管界对纳米颗粒在环境中行为的可靠数据的呼吁。了解生物转化如何影响工程纳米材料在环境中的行为，对于确保纳米技术在不超出支持它们的生态能力的情况下改善物质和社会条件是很重要的。此外，这个项目的学生将获得纳米化学和环境工程应用的宝贵的跨学科和协作经验。这个项目会使国家更强大吗？在一个合格的研究人员短缺的新兴需求领域，美国的研究和人力资源基础将有助于纳米技术的发展，使其成为一种可持续发展的工具，而不是一种环境责任。

CBET- 0829158 AlvarezRapid industrial scale production, coupled with unique material properties, underpin rising concerns of engineered nano-scale materials inadvertently impacting the health and function of natural systems. Carbon based nano-scale materials such as fullerenes and nanotubes in particular have been proposed for a variety of applications and are on track to be produced at industrial scales. Building a fundamental, quantitative understanding of material behavior in natural and engineered systems allows for accurate predictive behavior models which are critical for material life cycle assessment(s) necessary for risk mitigation and sustainability. Of particular interest is the biological interface at which these materials may interact as biologically mediated transformations of fullerenes could significantly influence their mobility, bioavailability, reactivity, toxicity and overall environmental impact. Yet, to date, no systematic evaluations of fullerene biotransformation has been conducted. They will seek to evaluate the susceptibility of aqueous available fullerene species to biochemical transformations and their biological significance. Specifically, they will: (1) characterize the rates and byproducts of biotransformation through, in part, the use of radio labeled P14PCB60B, (2) determine how biotransformation affects the toxicity of CB60B, and (3) quantify the bioavailability and bioaccumulation potential of P14PCB60B and its byproducts through model earthworm systems. They will test the hypotheses that: 1) CB60B can be oxidized by non-specific enzyme systems such as manganese peroxidase, which is involved in complex carbon macromolecules degradation via radical (OH) attack, and/or by other enzymes produced by cellulytic fungi or bacteria that degrade recalcitrant compounds; and (2) such biotransformations will decrease the toxicity and bioaccumulation potential of CB60B, but may increase its solubility and bioavailability. Using chemically unique CB60B with differential isotopic signatures, biotransformation investigations will be conducted with cell free (e.g. purified manganese peroxidase which catalyzes non-specific radical (OH) oxidation), and with whole cell, in vivo cultures of cellulytic fungi, PAH-degrading mixed cultures, and PAH-degrading pure cultures. Reaction kinetics and products will be characterized by a battery of analyses (Radiochromatography (HPLC), P13PC-NMR, MALDI-MS, UV/Vis, Scintillation Counting, among others). Corresponding toxicity studies will measure microbial heterotrophic activity before and after exposure to water available CB60B and bio-transformed derivatives. Bioaccumulation and availability of both C60 and corresponding derivatives will be evaluated through whole organism (model earthworm systems) and biomimetic sorbent experiments similar to previous studies done with polyaromatic hydrocarbons. This work responds to calls for reliable data on nanoparticle behavior in the environment that have come from environmental advocacy groups, the emerging nanotechnology industry and the regulatory community. Understanding how biotransformation affects the behavior of engineered nanomaterials in the environment is important to ensure that nanotechnology improves material and social conditions without exceeding the ecological capabilities that support them. Furthermore, students on this project will gain valuable interdisciplinary and collaborative experience with applications of nanochemistry and environmental engineering. This project will strengthen the nation?s research and human resource base in an emerging need area where qualified researchers are in short supply, and will contribute to the development of nanotechnology as a tool for sustainability rather than as an environmental liability.