Amperometric micro-biosensor array for choline and acetylcholine based on a glassy carbon electrode modified by platinum-black particles and a co-crosslinked enzyme system

A glassy carbon electrode was first modified by electro-depositing sub-micrometer platinum black particles on the surface. An acetylcholine micro-biosensor array and a choline micro-biosensor array were fabricated based on immobilization of acetylcholineasterase-choline oxidase or choline oxidase by cross-linking with glutaraldehyde on the Pt-black/GCE. Significant enhancement in performances of these biosensors was achieved. The chronoamperometric response of the acetylcholine micro-biosensor array gave a linear relation in the range of 29 to 1200 mu mol/L and a detection limit of 8.7 mu mol/L acetylcholine. The amperometric response of the choline micro-biosensor array gave a linear relation in the range of 24 to 1000 mu mol/L and a detection limit of 7.4 mu mol/L choline. They also possessed very good stability and reproducibility for long-term use.