Static and Kinetic Investigations of the Structural Ordering of Phospholipid Membranes Doped with Azobenzene Derivative

Abstract

An azobenzene containing a fatty acid derivative, 4-octyl-4′-(5-carboxypentamethyleneoxy)azobenzene (8A5), was incorporated into large unilamellar vesicles (LUVs) of L-R-dimyristoylphosphatidylcholine (DMPC), and its effects before and after photoisomerization (in trans and cis forms, respectively) on fast osmotic processes were observed by stopped-flow light scattering measurements. Differential scanning calorimetry (DSC) measurements revealed 8A5, in particular the cis form, to strongly perturb the membrane structure. More specifically, fast osmotic shrinkage of the LUVs was detected by the changes in the light scattering at 500 nm following the mixing of DMPC LUVs and an aqueous solution of betaine at high flow velocity. A rapid and novel type of the scattering signal was observed in the vicinity of the phase-transition temperature, suggesting the thermodynamic lateral reordering in the membrane due to the imposed osmotic pressure difference.

Photoinduced Motions in Azo-Containing Polymers

“…A series of other properties can be modified by light. For example, guest binding to eosin in solution is affected by the azobenzene configuration, generating a switch. , The actual polymer solubility is also affected by isomerization, and a whole literature is dedicated to phase separation and supramolecular structural ordering. − Surface tension and contact angles can also be modulated by light. More recently, photoconducting and photoluminescent polymers have been synthesized with azobenzene groups in the main chain 95 with the hope to impart the ability to control these properties by light.…”