DEVELOPMENT OF AN INDICATOR DISPLACEMENT ASSAY REAGENT FOR SACCHARIDE QUANTITATION

Abstract

Boronic acid-appended molecules have been popular in classical guest-host interactions with saccharides that use an integrated indicator-receptor motif. Though the literature shows a number of novel sensors varying in degrees of synthetic difficulty and water solubility, such sensor systems were never refined into a working analytical tool. A promising alternative to the classical guest-host based sensors is the competition-based indicator displacement assay (IDA). The same receptor in an IDA can be used for different indicators, allowing a tunable optical signal response. IDAs utilize reversibly bound indicators that are displaced by an analyte of interest, which eliminates the sometimes cumbersome synthetic steps of integrated systems. It has also been shown that IDAs can work in both aqueous and organic solvents. This research seeks to answer the question: Can a boronic acid-based indicator displacement assay reagent be developed into an analytical tool capable of quantitating saccharide levels in aqueous media? This work focused on expanding current boronic acid-based IDAs by developing two IDA reagents that utilize boric acid gel (BAG) as the base receptor. Alizarin red S-appended boric acid gel (BAG-ARS) is a colorimetric reagent and riboflavin-appended boric acid gel (BAG-RBF) is a fluorescent reagent, both of which can be detected visually and via absorbance or fluorescence spectroscopy, respectively. Each reagent was optimized and validated for the detection of saccharides in aqueous solution, and successfully applied to the detection of fructose in a white wine.