A simple method to fabricate fluorescent glucose sensor based on dye-complexed microgels

Abstract A simple method was developed to fabricate a fluorescent glucose sensor based on the complexation of low-cost anionic dye molecules with glucose-responsive microgels. A copolymer microgel of poly( N -isopropylacrylamide-co-acrylamide-co-acrylamidophenyl boronic acid) [p(NIPAM-AAm-PBA)] was used as template to complex the commercially available fluorescent dye, Bordeaux R. While the PBA moieties can reversibly bind with glucose to induce the volume phase transition of the microgels, the amide groups in the AAm units can bind the two sulfonate groups in each dye molecules so that the dye molecules can serve as additional crosslinkers and shrink down the size of microgels. The dye molecules assemble together and form stable structure domains in the microgel networks. The glucose-induced swelling of the polymer network can stretch the dye molecules and shift the π–π stacking in the dye assemblies, thus modulate the fluorescence intensity of the dye assemblies embedded in the microgels, enabling to convert chemical changes into optical signals. The resulted p(NIPAM-AAm-PBA)-Bordeaux R composite microgels demonstrated good reproducibility in fluorescent detection of glucose. The potential interferences from lactate and human serum albumin on the glucose sensor are not significant in the physiologically important glucose concentration range. The simple dye-microgel complexation method presented here opens a new door in the fabrication of miniature fluorescent glucose sensor for continuous monitoring of glucose.