Organogels from 1<i>H</i>-Imidazole Amphiphiles: Entrapment of a Hydrophilic Drug into Strands of the Self-Assembled Amphiphiles

Abstract

Linear 1H-imidazole amphiphiles (1−3) were synthesized by the esterification reaction of 4‘-alkyloxy phenol with 4-chlorocarbonyl imidazole. They formed organogels. When 1N of the imidazole head was blocked by an ethyl group, however, the compound (4) did not self-assemble. The SAX and TEM study revealed that in a dry gel state, the 1H-imidazole amphiphiles self-assembled into a fibrous aggregate having a reverse micellar cubic structure. Norfloxacin (NFLX), a fluorescent hydrophilic antibiotic, showed relatively weak fluorescence emission in THF/n-hexane (10-6 mol/mL) when excited at 280 nm. In the organogel of compound 3 (1.5 wt %) in THF/n-hexane, integrated fluorescence intensity of NFLX was enhanced approximately 10 times as compared to that in the THF/n-hexane solution or sol state, strongly suggesting that NFLX was trapped in the hydrophilic core of a micellar assembly of compound 3. The dry gel fibers were also strongly fluorescent under confocal laser scanning microscopy.