Glucose sensors based on a responsive gel incorporated as a Fabry-Perot cavity on a fiber-optic readout platform

An optical sensor for detection of glucose is implemented by incorporating a carbohydrate sensitive hydrogel as a Fabry-Perot cavity at the end of optical fiber for high sensitivity readout of the gel length. The glucose sensing functionality was achieved by incorporating boronic acid moieties into an acrylamide-based hydrogel. The interaction between glucose and boronic acid changes the driving forces for gel swelling thus inducing a glucose sensitive hydrogel swelling. The effects on the carbohydrate swelling response, with respect to sensitivity and selectivity, by incorporation of a cationic monomer, dimethyl-aminopropyl acrylamide, into the boronic acid functionalized responsive gels were determined. The linear gel swelling response in aqueous solutions at aqueous 2.5 mM carbohydrates were determined to -1760 nm/mM for glucose whereas mannose, sucrose, fructose and galactose displayed a response of about 10% of the glucose response for the hydrogels containing 10 mol% dimethylaminopropyl acrylamide. This gel composition with 10 mol% climethylaminopropyl acrylamide is the most promising for detection of glucose at physiological pH and ionic strength. A mechanism where carbohydrate specific stabilisation of the boronic acid group and possible carbohydrate mediated additional crosslinking of the elastically active polymer chains is suggested. (C) 2008 Elsevier B.V. All rights reserved.