Ultrasensitive electrochemiluminescence biosensor for determination of malathion based on a multiple signal amplification strategy

A novel electrochemiluminescence (ECL) biosensor for ultrasensitive detection of malathion was constructed by multiple signal amplification strategy. In this protocol, Ru(bpy)32+ (as luminophore) was firstly immobilized on hydroxyapatite (HAP) to produce a stable composite film on the electrode surface. ECL signal is amplified by the adsorption of more Ru(bpy)32+ onto HAP with high loading capacity. After Au@ZIF-7 nanocomposite (as co-reaction promoter) was modified to the electrode surface, the ECL signal was further increased. In addition, in order to enhance the selectivity of the sensor, the porosity of Au@ZIF-7 was used to load acetylcholinesterase (AChE). The ECL signal was significantly enhanced in the solution containing acetylthiocholine, possibly due to the promoting effect of the reaction products thiocholine of AChE and acetylthiocholine (ATCl). When the biosensor was incubated with malathion, ECL signal decreased gradually. Under optimal conditions, the linear range of malathion was wide in the range of 3.72 × 10−11 to 3.72 × 10−6 mol/L and the LOD of 1.32 × 10-11 mol/L. The method has the advantages of outstanding stability and good specificity. It had a potential application prospect in the detection of OPs.