Phospholipid membranes provide a stable barrier to the passage of water-soluble components, while oleic acid membranes are more permeable and fluctuating.
There are several means to program the membranes to modulate their barrier properties for the artificial cells:
(i) their formation itself can be programmed as shown for example in the opposite figure. There are technical difficulties with the final synthesis step, which are being investigated in sample microfluidic reactors. The programmable formation of gap attached flat membranes should also be technically feasible.
(ii) the permeability of the membranes can be modulated directly by electric fields (electroporation). Usually relatively high field strengths are required for this.
(iii) the permeability can be modulated by electric field induced concentration changes, such as pH
(iv) the permeability can be modulated by specific macromolecules (transported to the mem-brane by electric fields) e.g. then creating ion channels. Proteins are not required for this.