AsianScientist (Mar. 22, 2017) – A team of researchers at Kyoto University’s Institute for Integrated Cell-Material Sciences (iCeMS) have used polyhedral-shaped porous molecules to create an artificial ion channel. Their findings have been published in Chem.
Ion channels are porous proteins present in the membranes of all living cells. They are responsible for managing the transportation of ions across the cell membrane, creating electrical signals that initiate various cellular processes.
Most ion channels have a single opening, but a unique family of channels have two. Researchers would like to have a clearer understanding of how these two-pored channels work and whether they might be implicated in some diseases. Designing synthetic channels is one way to go about this.
The team led by Associate Professor Shuhei Furukawa first synthesized a molecule made of rhodium. The molecule is shaped like a cuboctahedron, with eight triangular and six square faces. The rhodium-based molecule was then embedded into a double layer of lipids. The team then synthesized short and long alkoxy chains made of hydrogen, carbon and oxygen molecules, which attached the molecule to the surrounding lipids.
They found that the rhodium-based molecule rotated inside the lipid bilayer, exposing at any one time either the smaller triangular- or larger square-shaped channel. Each shape led to a different state of electrical conductance. The molecule was also found to rotate more slowly when it was attached to the longer alkoxy chains, increasing the amount of time the channel remained open before the molecule continued its rotation.
“Rotational dynamics is the key to switching between distinct conductance states to expose either the triangular or square apertures to the aqueous phase,” the study authors said.
The team also found that changing the metal they used from rhodium to copper changed the molecule’s permeability: while the rhodium-based molecule is permeable to ions with two positive charges, like calcium, the copper-based molecule only transports ions with a single positive charge, like potassium.
Further studies are underway to improve the molecule’s design so the pores are open more often and the molecules can be switched from one state to the other using external stimuli.
The article can be found at: Kawano et al. (2017) Metal-Organic Cuboctahedra for Synthetic Ion Channels with Multiple Conductance States.
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Source: Kyoto University.
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