Impedimetric and amperometric bifunctional glucose biosensor based on hybrid organic-inorganic thin films

A novel glucose biosensor with an immobilized mediator was studied using electrochemical impedance spectroscopy (EIS) and amperometry measurements. The biosensor has a characteristic ultrathin form and is composed of a self-assembled monolayer anchoring glucose oxidase (GOx) covered with Langmuir-Blodgett (LB) films of Prussian blue (PB). The immobilized PB in the LB films acts as a mediator and enables the biosensor to work under a low potential (0.0 V vs. Ag/AgCI). In the EIS measurements, a dramatic decrease in charge transfer resistance (R-ct) was observed with sequential addition of glucose, which can be attributed to enzymatic activity. The linearity of the biosensor response was observed by the variation of the sensor response (1/R-ct) as a function of glucose concentration in the range 0 to 25 mM. The sensor also showed linear amperometric response below 130 mM glucose. The organic-inorganic system of GOx and PB nanodusters demonstrated bifunctional sensing action, both amperometry and EIS modes, as well as long sensing stability for 4 days. (C) 2014 Elsevier B.V. All rights reserved.