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  1. Abstract

    Pathogen contamination of water has a massive impact on global human health. In particular, viruses pose unique challenges to water treatment techniques due to their small size and presence in water as both individual virions and when absorbed onto larger particles. Low-energy water treatment processes such as media filtration are not capable of completely removing viruses owing to their small size. Hence, less sustainable processes with high chemical or energy consumption such as chemical disinfection, ultraviolet irradiation, and membrane filtration are usually required. To overcome high energy and/or chemical requirements for virus treatment, designs for sustainable fiber filters fabricated from minimally processed natural materials for efficient virus (MS2) and bacteria (E. coli) removal are presented in this work. These filters were created by functionalizing readily accessible natural fibers including cotton, silk, and flax with a simple aqueous extract containing cationic proteins fromMoringa oleiferaseeds. The proposed filters offer a comprehensive low cost, low energy, and low environmental impact solution for pathogen removal from water with removals of >7log10(99.99999%) for viruses and bacteria.

     
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  2. Aquaporins (AQPs) are naturally occurring water channel proteins. They can facilitate water molecule translocation across cellular membranes with exceptional selectivity and high permeability that are unmatched in synthetic membrane systems. These unique properties of AQPs have led to their use as functional elements in membranes in recent years. However, the intricate nature of AQPs and concerns regarding their stability and processability have encouraged researchers to develop synthetic channels that mimic the structure and properties of AQPs and other biological water-conducting channels. These channels have been termed artificial water channels. This article reviews current progress and provides a historical perspective as well as an outlook toward developing scalable membranes based on artificial water channels. 
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  3. The long-standing goal in membrane development is creating materials with superior transport properties, including both high flux and high selectivity. These properties are common in biological membranes, and thus mimicking nature is a promising strategy towards improved membrane design. In previous studies, we have shown that artificial water channels can have excellent water transport abilities that are comparable to biological water channel proteins, aquaporins. In this study, we propose a strategy for incorporation of artificial channels that mimic biological channels into stable polymeric membranes. Specifically, we synthesized an amphiphilic triblock copolymer, poly(isoprene)– block –poly(ethylene oxide)– block –poly(isoprene), which is a high molecular weight synthetic analog of naturally occurring lipids in terms of its self-assembled structure. This polymer was used to build stacked membranes composed of self-assembled lamellae. The resulting membranes resemble layers of natural lipid bilayers in living systems, but with superior mechanical properties suitable for real-world applications. The procedures used to synthesize the triblock copolymer resulted in membranes with increased stability due to the crosslinkability of the hydrophobic domains. Furthermore, the introduction of bridging hydrophilic domains leads to the preservation of the stacked membrane structure when the membrane is in contact with water, something that is challenging for diblock lamellae that tend to swell, and delaminate in aqueous solutions. This new method of membrane fabrication offers a practical model for making channel-based biomimetic membranes, which may lead to technological applications in reverse osmosis, nanofiltration, and ultrafiltration membranes. 
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