Membrane disk and sphere: controllable mesoscopic structures for the capture and release of a targeted object.

Design of molecules for self-assembled mesoscopic structures with specific functions is an important and interesting challenge that spans across disciplines such as nanosciences. A closed lipid membrane is a good example of a self-assembled mesostructure. In this study, we developed controllable membrane formation by making a subtle change at the molecular level. We utilized a synthetic photosensitive amphiphile (KAON12) to achieve the photobased molecular manipulation of the opening and closing of membranes through reversible transitions between sphere and disk structures. We found that the mechanism is based on the photoswitching of the membrane line tension, as deduced from the fluctuation of the membrane edge, through the action of KAON12. Furthermore, we demonstrated the controllable capture and release of colloidal particles into and from a membrane sphere. The observation of Brownian motion of the particle confirmed colloidal encapsulation. This successful photomanipulation of mesoscopic membrane structures in a noncontact and reversible manner should lead to a better understanding of the mechanism of membrane self-organization and may see wider application, such as in microreactors and drug-delivery systems.