A new fluorescent vesicular sensor for saccharides based on boronic acid-diol recognition on the interfaces of vesicles

A novel amphiphile containing two functional groups of both naphthalene and phenylboronic acid, p-((5-dodecyloxy-1-oxy) naphthalene) methyl-phenylboronic acid (DNMPBA), has been synthesized. The amphiphile has self-organized into vesicles in the selective solution of THF/water (phi=0.6) buffered at pH 6.86. The Tc of the vesicles from crystal to liquid crystal is 56.8degC. Addition of saccharides to the vesicular solution, the fluorescent intensities of naphthalene in DNMPBA vesicles centred at 345 nm increase dramatically with increasing concentration of saccharides. The changed tendency for fluorescent intensities of the DMNPAB vesicles with saccharides is similar to the other systems reported in literature to favor the binding with fructose over glucose and maltose. It is ascribed to boronic ester formation which might diminish the photoinduced electron transfer (PET) progress to induce fluorescence retrieval and, therefore, increase the fluorescence intensity. The vesicular sensor through the interactions between boronic acid and saccharides displayed at a biomimetic membrane interface can be detected by means of fluorescence intensities. The results suggest that the fluorescent vesicles might be used as biosensors to determine saccharides.