An Electrochemiluminescence Biosensor for Detection of Methyl Parathion With a Novel Probe Ru-MIL-100 via the Acetylcholinesterase Inhibition Coupled With the Reaction Between HAc and Triethylamine

It is of great significance to develop sensors for trace pesticide residues detection in food. Herein, an electrochemiluminescence (ECL) sensor with high sensitivity for the detection of methyl parathion (MP) was constructed by combining of the acetylcholinesterase (AChE) enzyme-inhibited reaction with tris-2,2'-bipyridyl ruthenium Ru(bpy)₃ ²⁺-triethylamine (TEA) system for the first time. A new ECL probe of MIL-100 loaded with Ru(bpy)₃ ²⁺(Ru-MIL-100) was synthesized, and then Ru-MIL-100 and AChE were immobilized on the electrode with Nafion. Triethylamine was used as a coreactant to form a Ru-MIL-100-TEA luminescence system. The hydrolysis of iodinated acetylthiocholine by AChE to generate acetic acid that consumes TEA, leading to the quenching of ECL of the Ru-MIL-100-TEA system. But MP can inhibit the activity of AChE, which leads to the decrease of the generated acetic acid and the enhancement of ECL. With the increase of the MP concentration, the ECL intensity increases. Due to the high catalytic activity of the AChE and the excellent ECL luminescence performance of the Ru-MIL-100 probe, the sensor is highly sensitive. The detection concentration range of MP was 1.0 × 10^-12-1.0 × 10^-9 mol/L, and the detection limit was 2.07 × 10^-13 mol/L. The biosensor was applied to the determination of MP in vegetable samples.