Building Better Bio-Beads: Engineering Modulation of pH and Metabolite Diffusive Flux in Hydrogels

氯化有机溶剂是美国地下水中最常见的污染物，这些化合物对供水的污染对公众健康构成重大风险，因为有几种已知的致癌物可能导致通过饮用水暴露。虽然工程师们已经开发出了利用微生物将这些污染物作为食物的能力的处理技术，但这一过程可能导致有害酸的产生，最终使活性停止。这项拟议中的研究将把这些有益的微生物屏蔽在称为生物珠的保护性胶囊中。这些胶囊将允许有益的微生物继续消耗氯化有机溶剂，同时产生清洁的水。这些生物珠可以与不同的微生物一起使用，以解决许多环境问题，并应用于许多其他领域，包括药物输送，制药，食品加工和废水处理。该项目将通过将研究纳入传统的本科实验室课程来增加本科生的学习机会。如果成功，该项目将有助于保护国家的水安全，并确保美国公众获得安全的饮用水。氯化有机溶剂，如三氯乙烯和全氯乙烯（TCE和PCE）是美国地下水中最常见的污染物，这些化合物对供水的污染对公众健康构成重大风险，因为有几种已知的致癌物可能导致饮用水暴露。虽然像PCE这样的化合物可以通过低成本的厌氧还原二氯化来破坏，但这个过程会降低pH值，导致更多可溶性，挥发性和危险降解产物的积累。微生物通过各种内部手段抵抗pH变化，包括质子流出和控制膜渗透性以限制运输。不幸的是，这些pH控制方法以代谢能量和微生物的最佳生长为代价。本提案的目的是解决目前缺乏的pH值控制的氯化溶剂生物修复利用现有的基本概念，从生物微胶囊化，混合有机-无机材料科学和质量传输理论。该研究将涉及构建一种生物珠，其目标是自我调节pH值控制。生物珠环境将被设计为模仿和改善微生物自然采用的pH和运输控制机制。生物珠包封的最终目标是在非理想的外部pH梯度中扩展包封的生物体的活性代谢范围。该生物珠设计将通过将生物启发机制并入分层胶囊设计中来实现，该分层胶囊设计通过添加缓冲基团来控制内部pH，调整静电结构电荷以限制带电物质运输，以及部署催化层，该催化层被设计为流出或与由外部光刺激驱动的质子反应。该研究将利用数百名一年级本科生科学家的组合力量，他们从事相关的主动学习，为实现项目目标提供有价值的数据。该奖项反映了NSF的法定使命，并被认为值得通过使用基金会的智力价值和更广泛的影响审查标准进行评估来支持。

Chlorinated organic solvents are the most common pollutants in groundwater in the U.S. Pollution of water supplies by these compounds represent a significant risk to public health, as several are known carcinogens that can result in exposure through drinking water. While engineers have developed treatment technology that uses the ability of microbes to consume these pollutants as food, the process can result in the production of harmful acids that eventually halts activity. The proposed research will shield these beneficial microbes in protective capsules called biobeads. These capsules will allow the beneficial microbes to continue to consume chlorinated organic solvents while producing clean water. These biobeads can be used with different microbes to address many environmental problems, with applications in many other fields including drug delivery, pharmaceuticals, food processing, and wastewater treatment. This project will augment undergraduate learning opportunities by incorporating the research into traditional undergraduate laboratory courses. If successful, this project will help protect the Nation's water security and ensure safe drinking water availability to the U.S. public. Chlorinated organic solvents like tri- and per-chloroethene (TCE and PCE) are the most common pollutants in groundwater in the U.S. Pollution of water supplies by these compounds represent a significant risk to public health, as several are known carcinogens that can result in exposure through drinking water. While compounds like PCE can be destroyed through low cost, anaerobic reductive dichlorination, this process can lower pH, resulting in the accumulation of more soluble, volatile, and hazardous degradation products. Microorganisms resist pH change through a variety of internal means, including proton efflux and control of membrane permeability to restrict transport. Unfortunately, these pH control methods come at the cost of metabolic energy and optimal growth of the microorganism. The objective of this proposal is to address the current deficiency of pH control in bioremediation of chlorinated solvents by leveraging existing fundamental concepts from biological microencapsulation, hybrid organic-inorganic material science, and mass transport theory. The research will involve building a biobead with the goal of self-regulated pH control. The biobead environment will be designed to emulate and improve on pH and transport control mechanisms naturally employed by microorganisms. The ultimate goal of biobead encapsulation is to extend the range of active metabolism for the encapsulated organism in non-ideal external pH gradients. This biobead design will be accomplished through incorporation of bioinspired mechanisms into a layered capsule design via addition of buffer groups to control internal pH, adjustment of electrostatic structural charges to restrict charged species transport, and deployment of catalytic layers designed to efflux or react with protons driven by external photic stimuli. The research will be leveraged by the combinatorial power of hundreds of first-year undergraduate student scientists engaged in relevant, active learning to provide valuable data to achieve project objectives.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.