Novel biosensor for acetylcholine based on acetylcholinesterase/poly (neutral red) - Deep eutectic solvent/Fe2O3 nanoparticle modified electrode

( )A highly sensitive acetylcholinesterase electrochemical biosensor for the determination of acetylcholine (Ach), a neurotransmitter essential for processing memory and learning, the lack of which is associated with Alzheimer's disease, has been developed. AChE was immobilized on a poly(neutral red) film formed by potential cycling electropolymerisation on Fe2O3 magnetic nanoparticle modified electrodes in acid-doped ethaline deep eutectic solvent. The influence of different acid dopants with anions NO3-, SO42-, Cl-,ClO4 on the rate of growth and electrochemical properties of the polymer films was studied and compared with PNR growth in aqueous solution. Modified electrode characterisation was carried out by voltammetry, electrochemical impedance spectroscopy, and scanning electron microscopy. Acetylcholinesterase enzyme was immobilized, using glutaraldehyde cross-linking, on the best polymer film Fe2O3 nanoparticle support, polymer formed in nitric acid-doped ethaline. The novel biosensor exhibited a limit of detection of 1.04 mu M for Ach, lower than reported in the literature, and had excellent reproducibility and long-term stability. It was successfully applied to the determination of ACh in synthetic urine, with excellent recoveries, which makes it a promising biosensor for clinical diagnosis of Alzheimer's disease.