Researchers mimic cell membranes to tune ion transport in artificial water filters

In every living cell, there are membranes, and in every membrane there are proteins, each of which acts as a chemical gatekeeper. Rather than passively letting ions pass in and out of the cell, these biochemical bouncers throw the door wide or shut it as needed. They let more life-sustaining materials like potassium or sodium through the cells' biological ion channels when the cell needs them, but shut off the flow before the chemical concentration gets too high.