An reagentless glucose biosensor based on direct electrochemistry of glucose oxidase immobilized on poly(methylene blue) doped silica nanocomposites

Conducting polymer nanocomposites have attracted a wide attention in material chemistry and analytical chemistry. In this work, poly(methylene blue) doped silica nanocomposites (PMB@SiO2(nano)) on glassy carbon electrode (GCE) were synthesized based on a two-step electropolymerization. Compared with poly(methylene blue) film, PMB@SiO2(nano) had more advantages in facilitating electron transfer between glucose oxidase (GOx) and the electrode surface. GOx immobilized on PMB@SiO2(nano) underwent a direct and reversible electrochemical reaction involving two-electron and two-proton exchange. A reagentless glucose biosensor using the nanocomposite modified electrode was developed. The calibration curve was linear over a glucose concentration range of 0.01–1.11 mM with a correlation coefficient of 0.998 and a detection limit (3σ) of 3 μM. The apparent Michalis–Menten constant, Km, for the enzymatic reaction was 0.50 mM. The developed biosensor presented good accuracy, repeatability, reproducibility and stability as well as an excellent ability to resist interference from ascorbic acid and uric acid species. The investigation indicates that PMB@SiO2(nano) has a good potential for application in construction of the third-generation enzyme biosensor as a conducting matrix material.