Optical glucose detection across the visible spectrum using anionic fluorescent dyes and a viologen quencher in a two-component saccharide sensing system

A very general system is described in which anionic fluorescent dyes possessing a wide range of absorbance and emission wavelengths are used in combination with a boronic acid-modified viologen quencher to sense glucose at pH 7.4 in buffered aqueous solution. The present study demonstrates this capability with the use of eleven anionic fluorescent dyes of various structural types. Signal modulation occurs as the monosaccharide binds to the viologen quencher and alters its efficiency in quenching the fluorescence of the anionic dyes. The degree of quenching and the magnitude of the glucose signal were found to correlate roughly with the number of anionic groups on the dye. Optimal quencher : dye ratios were determined for each dye to provide a fairly linear signal in response to changes in glucose concentration across the physiological range.