Superfast water transport and sieving mechanism of biomimetic nanofiltration membrane reinforced by aquaporin

The transmembrane aquaporin (AQP) protein with high permeability and selectivity have received substantial attention for preparing biomimetic membranes. However, the biological activity and loading mass of AQP in membranes are facing challenges. Here, AQP was expressed in E. coli cell membranes via genetic engineering, and then the cell membranes containing AQP were used to develop a biomimetic nanofiltration (NF) membrane, thereby maintaining the biological activity and increasing the loading mass of AQP. The membrane with high water permeance (66.5 L m -2  h -1 bar -1 ) exhibited a rejection sodium sulfate of 75.5% and high brilliant blue R rejection (99.8%), confirming the precise sieving ability of AQP. The membrane not only showed the typical sieving mechanism of the negatively charged NF membranes, but AQP possessed specialized water channels. This work provides some insights into the construction of high-performance biomimetic membranes using transmembrane proteins with high perm-selectivity and numerous choices in nature.