Photo responsive monoolein cubic phase containing coumarin-Tween 20 conjugates

Photo-responsive monoolein (MO) cubic phase was developed by incorporating coumarin-Tween 20 conjugate in the cubic phase. 7-chlorocarbonylmethoxycoumarin was obtained from 7-hydroxycoumarin through three-step reactions with the yield of 19.8% and it was conjugated to the head group of Tween 20. The molar ratio of the coumarin derivative/Tween 20 in the conjugate was about 1/1 on H-1 NMR spectrum. The cubic phase was prepared by melting the mixture of MO/conjugate (100/0.88, w/w) and hydrating the molten mixture with 5(6)-carboxyfluorescein (CF) solution. UV irradiation (254 nm and/or 365 nm) for 3 h resulted in 1.27% to 2.69% reduction in the double bond of MO but the cubic phase was stable in terms of its integrity under the UV irradiation. The release of CF from coumarin-Tween 20 conjugate-incorporated cubic phase was somewhat suppressed by being subjected to the UV irradiation. The head groups of coumarin-Tween 20 conjugate will be cross-linked so the diffusion in the water channel will be suppressed.