Effects of poly(allylamine) on the sugar-binding properties of a phenylboronic acid-appended azo dye

A phenylboronic acid-appended azo dye (Azo-PBA) binds saccharides and shows a color change at neutral pH. We investigated the effects of poly(allylamine) (PAA) on the binding property of Azo-PBA. The UV-visible absorption spectra of Azo-PBA were changed in the presence of PAA, depending on the concentrations. This result indicates the formation of Azo-PBA aggregates. In the absence of PAA, the binding constants of Azo-PBA to D-glucose and D-fructose were calculated to be 1.4 and 75 M^-1, respectively. In the presence of PAA, the binding constant to D-glucose was 130 M^-1, which was 93-times higher than the original binding constant, while the binding constant to D-fructosc was increased only 3.3-tirrics. These results show that the coexistence of PAA can selectively enhance the binding ability of Azo-PBA to D-glucose. However, it was found that a small amount of D-fruclose interfered in the measurement of D-glucose.