Novel potentiometric approach in glucose biosensor using silver nanoparticles as redox marker

A new approach in glucose biosensor based on polymeric membrane Ag-ISE fabricated from benzothiazole calix[4]arene was investigated. Silver nanoparticles (AgNPs) were synthesized and demonstrated for the first time to be used as a potentionmetic redox marker in a glucose biosensor. The linear relationship between logarithmic of H2O2 concentration and activity of free Ag releasing from silver nanoparticles was observed by direct potentiometry. Basically, the enzyme-substrate reaction between beta-D-glucose and glucose oxidase (GOx) produced H2O2 as a product. The generated H2O2 was able to oxidize AgNPs to free Ag+ ions. The amount of Ag+ ions corresponded to the concentration of glucose could be directly monitored using the Ag-ISE. The working linear range was 0.1-3 mM in 10 mM magnesium acetate buffer pH 6.0. Parameters affected the reaction rate such as pH and the amount of GOx and AgNPs were explored. The lower detection limit was 1.0 x 10(-5) M. The sensors exhibited very good repeatability with %R.S.D. < 7 and high sensor-to-sensor reproducibility. The proposed sensor provided a double selective function and could be used to determine glucose in beverages with good accuracy and precision. (C) 2008 Elsevier B.V. All rights reserved.