Amperometric acetylcholine biosensor based on self-assembly of gold nanoparticles and acetylcholinesterase on the sol–gel/multi-walled carbon nanotubes/choline oxidase composite-modified platinum electrode

A novel acetylcholinesterase (AChE)/choline oxidase (ChOx) bienzyme amperometric acetylcholine biosensor based on gold nanoparticles (AuNPs) and multi-walled carbon nanotubes (MWCNTs) has been successfully developed by self-assembly process in combination of sol–gel technique. A thiolated aqueous silica sol containing MWCNTs and ChOx was first dropped on the surface of a cleaned Pt electrode, and then AuNPs were assembled with the thiolated sol–gel network. Finally, the alternate deposition of poly (diallyldimethylammonium chloride) (PDDA) and AChE was repeated to assemble different layers of PDDA-AChE on the electrode for optimizing AChE loading. Among the resulting biosensors, the biosensor based on two layers of PDDA-AChE multilayer films showed the best performance. It exhibited a wide linear range, high sensitivity and fast amperometric response, which were 0.005–0.4 mM, 3.395 μA/mM, and within 15 s, respectively. The biosensor showed long-term stability and acceptable reproducibility. More importantly, this study could provide a simple and effective multienzyme immobilization platform for meeting the demand of the effective immobilization enzyme on the electrode surface.