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

1437630ElimelechSusChEM：下一代超选择性水通道蛋白基膜可持续水净化技术的发展从非传统水源（如咸淡水、海水和废水）中生产饮用水对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，其在世界范围内的应用预计将在未来显著增加。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方面具有重要的潜力。薄膜复合聚酰胺膜是目前用于这些工艺的最先进的技术。然而，尽管这些膜的盐去除率相对较高（99%），但它们对各种溶质的选择性不太理想，这导致了更高的能耗，增加了资本和运营成本。增加溶质选择性只能以显著降低水渗透性为代价，这是由于当前一代聚合物膜的渗透性和选择性之间的内在权衡。为了打破当前膜技术固有的渗透性和选择性权衡，迫切需要一种完全不同的膜设计方法。该项目还将促进多样性，并通过以下方式促进代表性不足的群体参与科学和工程：1)在少数民族服务机构建立生物分子工程研讨会；2)制定远程辅导计划，促进少数民族服务机构的STEM奖学金；3)积极参加促进科学和工程多样性的会议和研讨会；4)培训和激励本科生，关注科学和工程领域代表性不足的群体；5)参与内城的科学推广和科学指导。低收入的少数族裔学生。该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基水净化膜。提出的新方法利用水通道蛋白（一种仅对水渗透的完整细胞膜蛋白）的独特选择性，克服了当前膜固有的渗透性-选择性权衡。具体目标包括：研究水通道蛋白在由可聚合脂质或嵌段共聚物组成的囊泡中的结合和功能；培养对破裂技术、表面化学、脂质或嵌段共聚物化学以及水通道蛋白浓度对通过囊泡破裂形成系留支撑双分子层的影响的基本理解；在化学修饰的膜载体上制备稳定的超选择性水通道蛋白层；并对制备的膜进行表征，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，项目负责人提出了以下任务：1)水通道蛋白的表达和纯化；2)脂质或三嵌段共聚物的末端功能化，以允许双层系聚和聚合；3)用止流光散射法分析聚合脂质或聚合物囊泡中的水通道蛋白渗透率；4)评估模型表面的囊泡破裂技术和双层形成动力学；5)用表面改性的商业纳滤膜和手工铸造纳滤膜作为双层支撑制备含水通道蛋白的膜；6)评价制备膜在反渗透和正向渗透中的性能（水通量和溶质截留）；7)测试膜的机械和化学稳健性。他们会做到这一点，他们会：(i)研究水通道蛋白在可聚合脂质的功能，（ii）利用一种容易发生的化学反应使含水通道蛋白的囊泡发生共价破裂，（iii）研究共价辅助的含水通道蛋白囊泡破裂的沉积和破裂动力学，（iv）用化学方法将含水通道蛋白双层系在纳滤膜载体上，(v)评估基于水通道蛋白的平面膜对中性溶质（如氨、尿素和硼）的渗透性。对溶质超选择性的关注也不同于以前的膜开发工作，主要集中在最大限度地提高水渗透性。

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.