Aquaporin-based membranes made by interfacial polymerization in hollow fibers: Visualization and role of aquaporin in water permeability

Highly Permeable and Shelf-Stable Aquaporin Biomimetic Membrane Based on an Anodic Aluminum Oxide Substrate

“…These stringent requirements limit the transport, storage, and practicality of AQP membranes, thus precluding their industrial adoption and commercialization. A recently reported study shows that proteoliposomes, even in solution form at room temperature, lose their functionality within a week 33 , this also in good agreement with the previously reported studies mentioning the degradation or rupture of liposome structure in dry environment. To verify this, we stored the membrane under ambient conditions (25°C, 35% humidity) for 7 days without DI water, and analyzed the membrane surface morphology by FESEM analysis.…”

“…Our membrane shows superior water puri cation performance mainly due to the optimized fabrication of a substrate with a low surface roughness and a channel-type porous structure, which supports the water permeability performance of AQP. As previously reported membranes mostly utilized polymeric substrates which has low porosity as well as non-channel like pores which are unable to support the water permeability performance of pristine aquaporin liposomes as shown by several biophysical and stopped ow analysis 7,14,33 . Moreover, these membranes were fabricated mostly using interfacial polymerization (IP), in which the proteoliposomes were covered with a selective layer, most usually polyamide, so that most of the water permeability as well as the salt rejection was depended only on the characteristics of this selective layer or interfacial polymerization rather than on the proteoliposomes or AQP-liposomes 13,33,34 .…”

“…As previously reported membranes mostly utilized polymeric substrates which has low porosity as well as non-channel like pores which are unable to support the water permeability performance of pristine aquaporin liposomes as shown by several biophysical and stopped ow analysis 7,14,33 . Moreover, these membranes were fabricated mostly using interfacial polymerization (IP), in which the proteoliposomes were covered with a selective layer, most usually polyamide, so that most of the water permeability as well as the salt rejection was depended only on the characteristics of this selective layer or interfacial polymerization rather than on the proteoliposomes or AQP-liposomes 13,33,34 . Although we reported an electrokinetic coating method in our previous studies to uniformly coat a commercially available membrane for high water permeability, this membrane still does not fully support the permeability capabilities of aquaporin protein mainly due to the low porosity 7 .…”

“…Previously reported AQP membranes have strict environmental for storage, including a limited range of temperatures and humidity compatible with continuous hydration of the membrane before testing or after fabrication 33,[40][41][42] . These stringent requirements limit the transport, storage, and practicality of AQP membranes, thus precluding their industrial adoption and commercialization.…”

Anomalous Oligomerization Behavior of E. coli Aquaporin Z in Detergent and in Nanodiscs

“…Aquaporins (AQPs) constitute a family of tetrameric integral membrane proteins (IMPs) that permeabilize membranes to water and other solutes [1]. In particular, E. coli Aquaporin Z (AqpZ) permeabilizes cellular membranes to water with high selectivity [1][2][3][4] and is a workhorse for the fabrication of biomimetic membranes for water purification [5][6][7][8][9]. Despite differences in physiological features, selectivities, and permeabilities, all aquaporins oligomerize as homotetramers, as shown by the current 58 AQP structures in the Protein Data Bank (as of April 2023).…”