Glucose biosensors based on electrodes modified with ferrocene derivatives intercalated into Mg/Al layered double hydroxides

Two amperometric biosensors based on glassy carbon electrodes (GC) modified with Mg/Al layered double hydroxides (LDHs) containing ferrocene-carboxyl ate (Fc-CO2H) or ferrocene-sulfonate (Fc-SO3H), as interlayer anions, and glucose oxidase (GOx) are presented. Amperometric detection of glucose involves the electrochemical oxidation of H2O2 mediated by the ferrocene derivative. Optimization of the biosensors construction and of the operative conditions was investigated and is discussed herein. The performances of the two biosensors were evaluated by chronoamperometry, working at low anodic potentials (+0.400 V for Fc-CO2H and +0.500 V for Fc-SO3H vs. SCE). The linearity extended up to 1.5 mM and 10.0 mM in batch and in flow conditions, respectively, for both biosensors, whereas the sensitivity was higher for the one based on Fc-CO2H (4.8 +/- 0.3 versus 2.0 +/- 0.3 mu A mM(-1)cm(-2) in batch mode, and 63.9 +/- 0.4 versus 25.8 +/- 0.4 mu A mM(-1)cm(-2) in flow mode). The biosensors display rapid response time (less than 20 s), good reproducibility, as well as good operational stability. Glucose can be accurately determined in the presence of the most common interferences that coexist in blood serum if an oxidative membrane containing nanoparticles of MnO2 is applied on the biosensors' surface.