Amperometric enzymatic sensing of glucose using porous carbon nanotube films soaked with glucose oxidase.

Glucose oxidase was soaked into a porous carbon nanotube film coating on a platinum disk electrode, then trapped beneath a topcoat of electrodeposition paint. The resulting sensors, operated at a potential of +0.6 V (vs. Ag/AgCl), produced a glucose signal that was linear up to 40 mM, with a 50 μM detection limit. Signal stability over >100 h of continuous operation in a flow cell showed the remarkable functional durability of the biosensor, and confirmed that the electropaint coating effectively prevented loss of the enzyme. This performance is deemed to derive from the minimalistic immobilization layer design and the prevention of protein leakage. The immobilization method has a potentially wide scope, in that it may also be applicable in other types of enzymatic biosensor. Graphical abstract Illustration of an enzyme biosensor design that uses glucose oxidase in bare carbon nanotube electrode modifications with electropaint topcoat for amperometric glucose quantification. Immobilization matrix supplementation with extra functional (nano-) materials was unnecessary for high-quality and stable analysis performance.