SusChEM: Development of Next-Generation, Ultra-Selective Aquaporin-Based Membranes for Sustainable Water Purification

1437630消除水化学：开发用于可持续水净化的下一代超选择性水通道蛋白膜从非传统来源生产饮用水，如微咸水、海水和废水，对于增加全球供水至关重要。反渗透(RO)是海水淡化和废水回用的主导技术，预计未来其在世界范围内的使用量将显著增加。此外，一种新兴的膜技术--正向渗透(FO)在海水淡化、废水回用和高盐度盐水处理中具有重要的作用。薄膜复合聚酰胺膜是目前这些工艺中最先进的技术。然而，尽管这些膜具有较高的盐截留率(99%)，但它们对多种溶质的选择性并不理想，这导致了更高的能耗和更高的资本和运行成本。提高溶质选择性只能以显著降低水的渗透率为代价，这是由于当前一代聚合物膜在渗透性和选择性之间的内在权衡。迫切需要一种完全不同的膜设计方法，以打破当前膜技术固有的渗透性和选择性之间的权衡。该项目还将促进多样性，并通过以下方式加强代表不足的群体对科学和工程的参与：1)在少数群体服务机构设立生物分子工程讲习班；2)开发远程辅导计划，以促进少数群体服务机构的STEM奖学金；3)积极参加促进科学和工程多样性的会议和讲习班；4)培训和激励本科生，重点是科学和工程领域的代表不足的群体；以及5)参与对市中心低收入少数群体的科学宣传和科学指导。这项研究的总体目标是开发一种新型的、超选择性的水通道蛋白净水膜。所提出的新方法利用水通道蛋白的独特选择性，水通道蛋白是一种仅对水渗透的完整细胞膜蛋白，以克服当前膜固有的渗透性与选择性之间的权衡。具体目标包括：研究水通道蛋白在含有可聚合脂质或嵌段共聚物的囊泡中的掺入和功能；对破裂技术、表面化学、脂类或嵌段共聚聚合物化学以及水通道蛋白浓度对通过囊泡破裂形成可拴系的支撑双层膜的影响有一个基本的了解；在经过化学修饰的膜载体上制备稳定且超选择性的水通道蛋白双层；以及对所制备的膜进行表征，以评估膜的水通量和对各种溶质的选择性。为了完成该项目，PI提出了以下任务：1)表达和纯化水通道蛋白；2)脂类或三嵌段共聚合物的末端官能化以实现双层连接和聚合；3)使用停流光散射分析聚合脂质或聚合物小泡中水通道蛋白的渗透性；4)评估模型表面的囊泡破裂技术和双层形成动力学；5)使用表面改性的商用和手工铸造纳滤膜作为双层载体来制备含水通道蛋白的膜；6)评估所制备的膜在反渗透和正向渗透中的性能(水通量和溶液截留率)；以及7)测试膜的机械和化学稳定性。他们将完成这项工作：(1)研究可聚合脂质中的水通道蛋白功能；(2)利用易于发生的化学反应以共价方式破裂含水通道蛋白的囊泡；(3)研究共价辅助的含水通道蛋白的囊泡破裂的沉积和破裂动力学；(4)以化学方法将含水通道蛋白的双层系在纳滤膜支撑物上；以及(5)评估氨、尿素和硼等中性溶质对基于水通道蛋白的平面膜的通透性。对溶质超选择性的关注也不同于以往的膜开发努力，后者主要关注最大化水的渗透性。

1437630ElimelechSusChEM: Development of Next-Generation, Ultra-selective Aquaporin-based Membranes for Sustainable Water PurificationThe production of drinking water from non-traditional sources, such as brackish water, seawater, and wastewater, is critical to augmenting global water supply. Reverse osmosis (RO) is the dominant technology for desalination and wastewater reuse, and its worldwide usage is expected to significantly increase in the future. In addition, an emerging membrane technology, forward osmosis (FO), has the potential to play an important role in desalination, wastewater reuse, and treatment of high salinity brines. Thin film composite polyamide membranes are currently the state-of-the-art technology for these processes. However, despite the relatively high salt rejection of these membranes (99 %), they have less-than-ideal selectivity to a wide range of solutes, which leads to higher energy consumption and increased capital and operation costs. Increasing solute selectivity can only be achieved at the expense of significant decrease in water permeability due to the intrinsic trade-off between permeability and selectivity of current generation polymeric membranes. A radically different approach for membrane design is critically needed in order to break the inherent permeability-selectivity tradeoff of current membrane technologies. This project will also promote diversity and to enhance the involvement of under-represented groups in science and engineering by: 1) establishing a biomolecular engineering workshop at a minority serving institution, 2) developing a tele-tutoring program to facilitate scholarship in STEM at a minority serving institution, 3) actively participate in conferences and workshops that promote diversity in science and engineering, 4) training and inspiring undergraduate students, focusing on under-represented groups in science and engineering, and, 5) participation in science outreach and science mentoring of inner city, low-income minority students. The overall goal of the proposed research is to develop a novel, ultra-selective aquaporin-based membrane for water purification. The proposed new approach utilizes the uniquely selective nature of aquaporin, an integral cell membrane protein that is permeable only to water, to overcome the intrinsic permeability-selectivity trade-off of current membranes. Specific objectives include: studying aquaporin incorporation and functionality in vesicles comprising polymerizable lipids or block co-polymers; developing a fundamental understanding of the effects of rupture technique, surface chemistry, lipid or block co-polymer chemistry, and aquaporin concentration on the formation of tethered supported bilayers through vesicle rupture; fabricating a stable and ultra-selective aquaporin-based layer on top of a chemically-modified membrane support; and characterizing the fabricated membrane to assess membrane water flux and selectivity for a variety of solutes. To complete the project the PIs propose the following tasks: 1) expression and purification of aquaporin; 2) end-functionalization of lipid or triblock co-polymer to allow for bilayer tethering and polymerization; 3) analysis of aquaporin permeability in polymerized lipid or polymer vesicles using stopped flow light scattering; 4) assessment of vesicle rupture techniques and bilayer formation kinetics on model surfaces; 5) fabrication of aquaporin-containing membranes using surface-modified commercial and hand-cast nanofiltration membranes as a bilayer support; 6) evaluation of the performance (water flux and solute rejection) of fabricated membranes in reverse osmosis and forward osmosis; and, 7) testing the membrane mechanical and chemical robustness. They will accomplish this they will: (i) study aquaporin functionality in polymerizable lipids, (ii) utilize a readily-occurring chemical reaction to covalently rupture aquaporin-containing vesicles, (iii) study the deposition and rupture kinetics of covalent-assisted aquaporin-containing vesicle rupture, (iv) chemically tether an aquaporin-containing bilayer onto a nanofiltration membrane support, and, (v) assess planar aquaporin-based membrane permeability of neutral solutes, such as ammonia, urea, and boron. The focus on solute ultra-selectivity also differs from previous membrane development efforts, which largely focused on maximizing water permeability.