Novel chemical sensors using boronic acids for glucose detection

Abstract

Boronic acids (BAs) are well-­known for their interactions with diol-­containing compounds like glucose. Fluorescent moieties are commonly considered to enable monitoring of this interaction by changes in fluorescence. Incorporation of a BA component into charged molecules, can be used to induce quenching in the emission of a fluorescent molecule, thereby creating a two-­component sensing system1-­2. Hence, a novel cationic pyrimidine BA derivative, PBA, has been investigated for its indirect glucose sensing capabilities. In this approach, the fluorescence of 7-­hydroxycoumarin (7HC) is monitored. Increasing concentrations of our novel PBA sensor, quenches the fluorescence of 7HC by 98% (Fig. 1A). The decrease in fluorescence intensity of the system is achieved through electrostatic and p-­p stacking interactions between the fluorophore and PBA-­quencher1-­2. In the presence of saccharides, the Lewis acidic BA moiety of the sensor is known to form strong, reversible interactions2. This leads to the formation of an anionic boronate diester2, resulting in the dissociation of the BA-­quencher and fluorophore complex, causing a sequential recovery of fluorescence in 7HC1-­2 by 16% (Fig. 1B). This glucose-­sensing switch can be used to indirectly quantify glucose concentrations. Moreover, the inclusion of anchoring moieties in to the PBA-­quencher shows potential for the incorporation of this molecule into soft hydrogel platforms