Amperometric glucose biosensor based on screen-printed carbon electrodes mediated with hexacyanoferrate-chitosan oligomers mixture

A glucose oxidase (GOD) biosensor has been described based on screen-printed carbon electrodes (SPCEs) with hexacyanoferrate(III) (i.e. ferricyanide, FerTi) used as an electron transfer mediator. Mixing with chitosan oligomers (COs), a Ferri-COs mixture was drop-coated onto the surface of SPCEs, and GOD was then layered on, forming a GOD/Ferri-COs glucose biosensor. Thus, a disposable and low-cost biosensor can be fabricated easily, simply and rapidly. The characteristics of the sensor were studied by cyclic voltammetry, chronopotentiometry and amperometry. Sensors without GOD layering-on showed a quasi-reversible reaction of the redox couple (Ferri/ferrocyanide), and a significant enhancement of the sensor response signal could be obtained in the presence of COs. In addition, effects of GOD loading, COs concentration, solution pH and applied potential on the response of the glucose biosensor were also investigated. At an applied potential of 0.3 V, the biosensor exhibited a relatively fast response (response time was less than 20 s), low detection limit (ca. 1.38 mM), good reproducibility and high sensitivity (ca. 0.677 mu A mM(-1)) with a wide linear range up to 33.3 mM of glucose. (c) 2005 Elsevier B.V. All rights reserved.