Mechanically robust and highly permeable AquaporinZ biomimetic membranes

Seawater desalination and water reuse using membrane technology can provide a sustainable water supply to the world if such processes can be more energy-efficient. To harness the highly efficient water transport used by nature, it is proposed to incorporate trans-membrane water channel, AquaporinZ (AqpZ), into biomimetic membranes. However, the biomimetic membranes are intrinsically too fragile to be used in water purification. Here, we report a robust vesicular biomimetic membrane design and the synthesis route. The membrane is formed by cross-linking AqpZ-embedded block copolymer vesicles, followed by immobilizing vesicles on the membrane support via covalent binding, and then stabilizing through an optimized layer-by-layer polydopamine (PDA)–histidine (His) coating process. As compared with commercially available HTI membranes, the AqpZ-embedded vesicular membrane shows an order-of-magnitude increment in water flux (17.6 L/m2/h) with high salt retention (91.8%) when using 6000 ppm NaCl as the feed and 0.8 M sucrose as the draw solute in the forward osmosis operation. Thus, the vesicular membrane design may provide new insights into the design and fabrication of Aqp-embedded biomimetic membranes.