Photoinitiated Polymerization-Induced Self-Assembly in the Presence of Surfactants Enables Membrane Protein Incorporation into Vesicles

Photoinitiated polymerization-induced self-assembly (photo-PISA) is an efficient approach to predictably prepare polymeric nanostructures with a wide range of morphologies. Given that this process can be performed at high concentrations and under mild reaction conditions, it has the potential to have significant industrial scope. However, given that the majority of industrial (and more specifically biotechnological) formulations contain mixtures of polymers and surfactants, the effect of such surfactants on the PISA process is an important consideration. Thus, to expand the scope of the methodology, the effect of small molecule surfactants on the PISA process, specifically for the preparation of unilamellar vesicles, was investigated. Similar to aqueous photo-PISA findings in the absence of surfactant molecules, the originally targeted vesicular morphology was retained in the presence of varying concentrations of non-ionic surfactants, while a diverse set of lower-order morphologies was observed for ionic surfactants. Interestingly, a critical micelle concentration (CMC)-dependent behavior was detected in the case of zwitterionic detergents. Additionally, tunable size and membrane thickness of vesicles were observed by using different types and concentration of surfactants. Based on these findings, a functional channel-forming membrane protein (OmpF porin), stabilized in aqueous media by surfactant molecules, was able to be directly inserted into the membrane of vesicles during photo-PISA. Our study demonstrates the potential of photo-PISA for the direct formation of protein-polymer complexes and highlights how this method could be used to design biomimicking polymer/surfactant nanoreactors.