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 coreaction 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 x 10-11 to 3.72 x 10-6 mol/L and the LOD of 1.32 x 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.

Automated summary

A novel electrochemiluminescence (ECL) biosensor with multiple signal amplification strategy was constructed for ultrasensitive detection of malathion. The ECL signal was amplified by immobilizing Ru(bpy)32+ (as luminophore) on hydroxyapatite (HAP) and further increased by modifying Au@ZIF-7 nanocomposite (as coreaction promoter) to the electrode surface. Acetylcholinesterase (AChE) was loaded on the porous Au@ZIF-7 to enhance the selectivity of the sensor. The method showed wide linear range and high sensitivity in detecting malathion, with potential application prospect in OPs detection.