Colorimetric Sugar Sensing Using Boronic Acid-Substituted Azobenzenes

Abstract

In association with increasing diabetes prevalence, it is desirable to develop new glucose sensing systems with low cost, ease of use, high stability and good portability. Boronic acid is one of the potential candidates for a future alternative to enzyme-based glucose sensors. Boronic acid derivatives have been widely used for the sugar recognition motif, because boronic acids bind adjacent diols to form cyclic boronate esters. In order to develop colorimetric sugar sensors, boronic acid-conjugated azobenzenes have been synthesized. There are several types of boronic acid azobenzenes, and their characteristics tend to rely on the substitute position of the boronic acid moiety. For example, o-substitution of boronic acid to the azo group gives the advantage of a significant color change upon sugar addition. Nitrogen-15 Nuclear Magnetic Resonance (NMR) studies clearly show a signaling mechanism based on the formation and cleavage of the B–N dative bond between boronic acid and azo moieties in the dye. Some boronic acid-substituted azobenzenes were attached to a polymer or utilized for supramolecular chemistry to produce glucose-selective binding, in which two boronic acid moieties cooperatively bind one glucose molecule. In addition, boronic acid-substituted azobenzenes have been applied not only for glucose monitoring, but also for the sensing of glycated hemoglobin and dopamine.

Boronic acid-modified poly(amidoamine) dendrimers as sugar-sensing materials in water

“…Successful boronic acid sugar receptors used in direct sensing are often multivalent in order to overcome the high solvation enthalpies of sugars in water. [14][15][16] To increase the solubility of such receptors in water, the boronic acids have been covalently linked to water-soluble polymers, 17 or bound to a charged moiety. 18 Selectivity has been typically difficult to achieve.…”

Sugar-responsive pseudopolyrotaxanes and their application in sugar-induced release of PEGylated insulin

“…PBA reacts with cis-diol functional groups of sugars to form a five-or six-membered ring via ester bonds. As a result, PBA derivatives have been widely investigated as sugar-recognition motifs in chemical probes for sugar analysis [27][28][29][30][31][32] and sugar-sensitive Ins release systems [33][34][35]. We recently synthesized PBA-modified CyDs (PBA-CyDs) and found that they form supramolecular structures [36].…”

Polyol-responsive pseudopolyrotaxanes based on phenylboronic acid-modified polyethylene glycol and cyclodextrins

“…The boronate form can interact with the diol moiety of a polyol to form a cyclic ester; the reaction is rapid and reversible, and a state of equilibrium can therefore be achieved depending on the concentration of the polyol [14]. Utilizing this rapid and reversible reaction of PBA, analytical chemists have attempted to create chemical sensors to monitor blood D-glucose (Glc) levels [15][16][17][18]. Furthermore, some pharmaceutical scientists have attempted to incorporate PBA as a sugar recognition motif into insulin delivery systems in which the interaction between PBA and Glc is expected to function as a trigger for insulin release [19][20][21][22].…”