Single molecule measurements of channel proteins incorporated into biomimetic polymer membranes

Lipid bilayer membranes have been extensively utilized to examine membrane channel and pore proteins and are the subjects of study in their own right. There has been considerable recent interest in developing technologies to substitute or strengthen lipid bilayer membranes for a number of applications, including sensing or drug delivery. In particular, biomimetic amphiphilic block co-polymers have been shown to have the capacity to form membrane structures and to contain membrane proteins within them. In this work, we describe the creation of biomimetic membranes from a 5.7 nm thick tri-block co-polymer and the investigation of the effects of the polymer environment on incorporated channel proteins (alpha-haemolysin, OmpG, and alamethicin) with single molecule transport measurements. We found that the polymer membranes consistently have seal resistances of tens of G Omega and greater, and that the conductance of single channels is reduced by approximately 10% from that measured in diphytanoyl phosphatidylcholine lipid membranes, possibly as a result of increased cohesion of the polymer compared to lipid. The voltage gating ability and threshold voltages of voltage gated channels were also found to be very similar in the lipid and polymer environments.