A novel glucose biosensor based on the nanoscaled cobalt phthalocyanine-glucose oxidase biocomposite

We report on the utilization of a novel nanoscaled cobalt phthalocyanine (NanoCoPc)-glucose oxidase (GOD) biocomposite colloid to create a highly responsive glucose biosensor. The biocomposite colloid is constructed under enzyme-friendly conditions by adsorbing GOD molecules on CoPc nanoparticles via electrostatic interactions. The glucose biosensor can be easily achieved by casting the biocomposite colloid on a pyrolytic graphite electrode (PGE) without any auxiliary matter. It has been found that GOD can be firmly immobilized on PGE surface and maintain its bioactivity after conjugating with NanoCoPc. NanoCoPc displays intrinsic electrocatalytic ability to the oxidation of the product of enzymatic reaction H2O2 and shows a higher catalytic activity than that of bulk CoPc. Under optimal conditions, the biosensor shows a wide linear response to glucose in the range of 0.02-18 mM, with a fast response (5 s), high sensitivity (7.71 μA cm−2 mM−1), as well as good thermostability and long-term life. The detection limit was 5 μM at 3σ. The general interferences coexisted in blood except ascorbic acid and l-cysteine do not affect glucose determination, and further coating Nafion film on the surface of the biosensor can effectively eliminate the interference from ascorbic acid and l-cysteine. The biosensor with Nafion film has been used for the determination of glucose in serum with an acceptable accuracy.