Sugar response of boronic acid-substituted azobenzene dye-modified polymer

We synthesized a boronic acid-appended azobenzene dye (BA) and attached it to poly(ethyleneimine) (polyBA) for studying its sugar response. The addition of d-glucose induced a significant change in the UV–visible absorption spectra of the polyBA solution. The binding constants for d-glucose (Kglu) and d-fructose (Kfru) were calculated to be 54 M− 1 and 110 M− 1, respectively. The selectivity for d-glucose was higher in polyBA as compared with that of monomeric BA (Kglu = 1.2 M− 1, Kfru = 17 M− 1). We also fabricated multilayered films composed of polyBA and polyanions {poly(vinyl sulfate) (PVS), carboxymethylcellulose (CMC)} using a layer-by-layer deposition technique. In (PVS/polyBA)10 films, the affinity for d-glucose was relatively low (Kglu = 1.7 M− 1, Kfru = 28 M− 1). In contrast, (CMC/polyBA)5 films showed a high affinity for d-glucose (Kglu = 18 M− 1, Kfru = 42 M− 1). The loosely packed structure of the (CMC/polyBA)5 film and the suitable chemical structures of CMC probably led to a high affinity for d-glucose.