Over the years, light has been widely used as an effective trigger in biotechnology to interrogate biological systems and provide a conditional control over the complex cellular processes. Of particular advantage are the reversibility, physiological compatibility and high spatiotemporal precision of photo-induced processes. Understanding the fundamental biophysics of light-triggered changes in bio-systems is crucial for cell viability and optimization of clinical applications of light-induced processes in optogenetics and photopharmacology. Here, we employ cell-sized giant unilamellar vesicles (GUVs) to investigate light-triggered changes on the material properties of membranes doped with azobenzene-phosphatidylcholine (azo-PC ) as a photoswitch. In particular, we examined light-triggered vesicle area change, reversibility and kinetics of photoswitching and membrane bending rigidity. We show that light can be used to manipulate the shape and mechanics of these synthetic cells. Light-induced changes in vesicle area were quantified by employing vesicle electro-deformation. Our studies demonstrated membrane area increase due to cis photoisomerization of azo-PC which is consistent with results from molecular dynamics simulations. At high azo-PC fractions (&gt;50 mol%), large and complex shape transformations were observed. Photoswitching was reversible but showed faster kinetics from cis to trans isomerization. Trans-to-cis isomerization of azo-PC rendered the membrane softer. With increasing fractions of trans azo-PC the GUV membrane stiffens, while increasing cis-azo-PC fraction softens the membrane. Our results demonstrate that membrane mechanics could be easily controlled for azo-PC containing membranes through light.

Modulating membrane shape and mechanics by light

ACS Spring 2022

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.