Enzyme-free electrochemical glucose sensing

Schematic diagram of the electro-deposition processes of CS-RGO–NiNPs on SPE surface and its Glc detection mechanism. (a) polypropylene, (b) carbonelectrical contacts, (c) conductivepaths, (d) Insulting dielectric, (e) carbon counter electrode, (f) carbon working electrode, (g) Ag/AgCl pellet reference electrode. Synthesis (upper part of the figure): the synthesis reaction begins with the formation of nanocomposite precursors by electrostatic and hydrophobic interactions between negatively charged GO and positively charged Ni2+ and CS chains. With cathodic potential applied, protons in the acid solution around the electrode surface are consumed, causing relatively high localized pH. As a result, CS chains in the nanocomposite precursors near the electrode become insoluble and deposited from bulk solution together with GO and Ni2+. On the electrode surface, GO and Ni2+ are in situ reduced into RGO and NiNPs and deposited simultaneously with the deposition of CS. Detection (lower part of the figure): the detection reaction under applied anodic constant potentials starts with oxidation of Ni(0) into Ni(II) species such as Ni(OH)2 and NiO. These Ni(II) species are then further oxidized into strongly oxidizing Ni(III) species as NiO(OH) which electrochemically catalyzes the oxidation of glucose into gluconolactone liberating two hydrogen atoms. Meanwhile, NiO(OH) itself is reduced back into Ni(II) species.

http://www.sciencedirect.com/science/article/pii/S0956566313002212