An optical glucose biosensor based on entrapped-glucose oxidase in silicate xerogel hybridised with hydroxyethyl carboxymethyl cellulose

An optical glucose biosensor was fabricated by entrapping glucose oxidase (GOx) within the xerogel that was derived from tetraethylorthosilicate and hybridised with hydroxyethyl carboxymethyl cellulose polymer. The entrapped-GOx was mainly characterised with its long-lasting apparent biocatalytic activity as compared to that being entrapped in only sol–gel matrix. The biocatalytic activity of the entrapped-enzyme has extended its shelf lifetime up to 3 years. This long-term stability was closely correlated with the reduction in the shrinkage process of the hybrid gel being used. In conjunction with an optical oxygen transducer, the entrapped-GOx was assembled as an optical glucose biosensor comprised a sample flow system with which the dissolved oxygen in the sample could be precisely controlled and varied. The analytical working range was tuneable within 9.0 (mu)M–100 mM range depending on the dissolved oxygen concentration in the test solution. The time taken to reach a 95% steady signal was 6–9 min at flow rate of 1.0 mL min^-1. The glucose biosensor has been satisfactorily applied to the determination of glucose contents of urine samples.