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 potentiometric 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 β-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 × 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.