We report on photolipid
doping of giant unilamellar vesicles
(GUVs) via vesicle fusion with small unilamellar
photolipid vesicles
(pSUVs), which enables retroactive optical control of the membrane
properties. We observe that vesicle fusion is light-dependent, if
the phospholipids are neutral. Charge-mediated fusion involving anionic
and cationic lipid molecules augments the overall fusion performance
and doping efficiency, even in the absence of light exposure. Using
phosphatidylcholine analogs with one or two azobenzene photoswitches
(azo-PC and dazo-PC) affects domain formation, bending stiffness, and
shape of the resulting vesicles in response to irradiation. Moreover,
we show that optical membrane control can be extended to long wavelengths
using red-absorbing photolipids (red-azo-PC). Combined, our findings present
an attractive and practical method for the precise delivery of photolipids,
which offers new prospects for the optical control of membrane function