Controlling molecular assembly by analytes is attractive for analytical techniques. Herein, we designed and synthesized amphiphilic boronic acid fluorescent probes (B-Nap-C8) possessing naphthaleneboronic acid as a saccharide recognition site and alkyl chain as a hydrophobic moiety. We evaluated their saccharide recognition function in relation to the fluorescent or absorption intensity changes of the assembled B-Nap-C8. Also, we evaluated the saccharide recognition function of B-Nap-C8 by the effect of co-surfactants. B-Nap-C8 forms micelles and recognizes fructose at pH 10. In the presence of surfactants, B-Nap-C8 with the cetyltrimethylammonium bromide (CTAB) micelle can recognize fructose at neutral pH. On the other hand, B-Nap-C8 with the sodium dodecyl sulfate (SDS) micelle recognizes fructose at pH > 10. This is caused by the decrease of the apparent pK a of B-Nap-C8 on the surface of the cationic CTAB micelle. The micelle formation of B-Nap-C8 with CTAB was confirmed by TEM observation, and the critical micelle concentration of B-Nap-C8 with CTAB was determined to be 1.79 mM from the CTAB titration measurements. From the saccharide titration experiments, B-Nap-C8 with CTAB micelles selectively recognizes fructose at neutral pH. The selectivity for saccharides was not observed in the saccharide titration of B-Nap-C8 with SDS. Thus, the co-surfactant systems with B-Nap-C8 were found to control the selectivity for saccharide recognition in water.
ASJC Scopus subject areas
- Chemical Engineering(all)