Tailoring the pKa of Functional Polyelectrolytes for Saccharide Detection

In this research, sugar-binding polymers were synthesized and characterized. The need for glucose monitoring devices has driven researchers to innovate robust, miniature, low-cost sensors. Potential materials for such devices include polymers containing boronic acids. Boronic acids are synthetic, enzyme-free saccharide receptors. One way to optimize the performance of boronic acid-based sensors is in adjusting the pK_a to be near the desired operating pH, usually 7.4. Our approach is to modify the ratio of boronic acids and pyridine groups on a synthetic polymer. The alkylation of Poly(4-Vinyl Pyridine) was carried out to produce a cationic boronic acid-containing polymer. The extent of alkylation allows control of receptor spacing, charge, and solubility of the polymer. An acid-base titration was performed to characterize the Lewis acidity (pK_a). Using spectrophotometry, an allosteric indicator-displacement assay was utilized to measure binding affinity between the polymer and monosaccharides. Through this research, we can determine how the polymer composition affects both pK_a and solubility of the system in aqueous solution.  These results will contribute to a better rational design of sugar-binding polymers that perform at physiological pH.