A novel sensitive amperometric choline biosensor based on multiwalled carbon nanotubes and gold nanoparticles.

A novel amperometric biosensor for choline determination has been developed, exploiting the electrocatalytic properties of multiwalled carbon nanotubes (MWCNT) and gold nanoparticles (GNP). Chitosan (Chit), a natural biocompatible polymer, was used to disperse CNT, then Chit-MWCNT was dropped on the surface of a glassy carbon electrode (GCE), followed by GNP; finally, choline oxidase (ChOx) was immobilized by glutaraldehyde crosslinking. The ChOx/(GNP)4/MWCNT/GCE exhibited linear response to choline from 3 to 120µM, the sensitivity was 204µAcm-2mM-1 and the detection limit was 0.6μM. The biosensor exhibited good intra and inter-electrode precision, and excellent selectivity and stability. Electrochemical impedance spectroscopy (EIS) was also used to measure choline at 0.0V and this is the first report on choline determination by EIS. Successful measurement in milk samples was performed.