An optical glucose biosensor with eggshell membrane as an enzyme immobilisation platform

An optical glucose biosensor using an enzyme-immobilised eggshell membrane and oxygen-sensitive optode membrane for glucose determination has been developed. Glucose oxidase was covalently immobilised on an eggshell membrane with subsequent covering of the surface with an oxygen-sensitive optode membrane. The oxygen-sensitive membrane was constructed from tris(4,7-diphenyl-1,10-phenanthroline)ruthenium(II) ditetrakis(4-chlorophenyl) borate adsorbed on silica gel particles and dispersed in a silicone rubber film. The glucose biosensor was built by positioning both enzyme-immobilised eggshell and oxygen-sensitive optode membranes in a laboratory-made flow cell. The detection scheme was based on the depletion of dissolved oxygen content upon exposure to glucose solution and the rate change in fluorescence intensity of the oxygen-sensitive membrane was monitored and related to the glucose concentration. The effect of dissolved oxygen content, pH, temperature, phosphate buffer concentration and potential interferents has been studied in detail. The glucose biosensor demonstrated a long shelf-life compared with an enzyme-immobilised cellulose membrane. It has been successfully applied to the determination of glucose content in a beverage sample.