Methylene blue-functionalized ZIF-8/Au nanoparticle composites based ratiometric electrochemical sensor for reliable detection of methyl parathion in vegetables.

A novel ratiometric electrochemical sensor based on methylene blue-functionalized ZIF-8/Au nanoparticle composites (ZIF-8@MB/AuNPs) was constructed for reliable detection of methyl parathion (MP). The ZIF-8@MB/AuNPs composites were prepared by a simple and mild room-temperature method. Here, ZIF-8 was served as a support for loading functional nanomaterials, which helps to improve the adsorption and accumulation capacity for MP. The functional electroactive molecule methylene blue (MB) was adopted to produce a stable reference signal and form a ratiometric sensing strategy, offering more accurate and reliable detection results. The decoration of Au nanoparticles can effectively enhance the conductivity and catalytic activity of the composites. The obtained ZIF-8@MB/AuNPs composites exhibited a superior electrochemical catalytic performance toward MP. According to the ratiometric signal of I/I, the developed sensor offered a detection range of 0.05-30 μg mL and exhibited favorable selectivity, reproducibility and stability, and satisfactory applicability in vegetable samples.