Neutral pH monosaccharide receptor based on boronic acid decorated poly(2-hydroxyethyl methacrylate): Spectral Methods for determination of glucose-binding and ionization constants

Abstract

Herein, a glucose-responsive polymer featuring boronic acid has been synthesized that operates under physiological conditions. Phenylboronic acid-containing polymer has been successfully synthesized in two reaction steps using atom transfer radical polymerization (ATRP) of 2-hydroxyethyl methacrylate (HEMA) and post-polymerization modification of the obtained polyHEMA with 4-carboxyphenylboronic acid. The structure of the synthesized polyHEMA and polyHEMA-PBA has been investigated by size exclusion chromatography (SEC), proton nuclear magnetic resonance (1H NMR), and Fourier-transform infrared spectrometer (FT-IR). Interaction of polyHEMA-PBA with D(+)-glucose has been studied by Ultraviolet visible (UV–vis.) spectroscopy. Determined pKa values were approximately 7.8 and 7.9 by pH titration and Spectral Difference Methods, respectively. Also, the binding constant of polyHEMA-PBA with glucose has been determined 121 M−1 by Spectral Difference Methods. Dynamic light scattering (DLS) and field emission scanning electron microscopy (FE-SEM) have been utilized to investigate dual pH- and diol (glucose)-responsive behavior of polyHEMA-PBA. Aggregates and unimers (smaller objects) have been observed below and above the pKa of the polyHEMA-PBA, respectively. Upon addition of glucose to polyHEMA-PBA solution at pH = 7.4 aggregates dissociated into molecularly dissolved unimers of polyHEMA-PBA.