A novel electrochemiluminescence choline biosensor based on biofunctional AMs-ChO biocomposite

• A novel biofunctional AMs-ChO biocomposite was synthesized to construct an ECL choline biosensor.
• The excellent electrocatalytic activity of GR, Fe3O4 and TiO2 towards H2O2 could enhance the luminol ECL.
• With the prominent electroactivity of AuNPs to the oxidization of luminol, amplified ECL signal could be obtained.
• The detection limit is lower than that of the regularly reported biosensors.
• The choline biosensor exhibits high sensitivity, satisfying selectivity, good repeatability and stability.

In this work, a novel electrochemiluminescence (ECL) biosensing system for the sensitive and selective detection of choline was creatively designed based on the smart integration of multifunctional nanocomposites and a certain enzymatic reaction. Firstly, graphene-Au-chitosan (GR-Au-CS) nanocomposite, which possesses the property of intensification effect on luminol ECL, was electrochemically deposited on the bare GCE. Then, a biofunctional Fe3O4-TiO2-ChO biocomposite was unprecedentedly synthesized with combining the mimic peroxidase activity of Fe3O4 and the intensification effect of TiO2 on the luminol ECL. Thus, on the basis of smart integration of the above nanocomposites and the detection of H2O2 generated by ChO enzymatic reactions under the optimal conditions, the obtained ECL biosensor for choline showed wide linear range from 3 nM to 1.12 mM with detection limit (signal-to-noise ratio of 3) of 1 nM. The excellent performance of the biosensor shows that this method opens up a new avenue in the practical application.