MONOALKYLFERROCENE-MEDIATED AMPEROMETRIC ENZYME ELECTRODES FOR GLUCOSE DETERMINATION

Amperometric biosensors for the determination of beta-D-glucose are de scribed. Glucose-sensitive graphite electrodes are prepared by adsorpt ive immobilization of n-butylferrocene (n-BFc), tert-butylferrocene (t -BFc), or ethylferrocene (EFc). Glucose oxidase from Aspergillus niger is immobilized on the monoalkylferrocene-modified surfaces of the gra phite electrodes by covalent attachment. The biosensors based on n-BFc , t-BFc, and EFc could be used at potentials of 0.3, 0.325, and 0.275 V, respectively (vs. SCE reference electrode). A linear steady-state c urrent response, proportional to the glucose concentration in a range of 1-20 mM, is observed for the t-BFc- and EFc-mediated enzyme electro des. Data are presented on the influence of potential, oxygen, pH, and temperature upon the electrodes. Results are discussed on the basis o f the structural features of the mediators.