Ultrasensitive electrochemiluminescence biosensor for organophosphate pesticides detection based on carboxylated graphitic carbon nitride-poly(ethylenimine) and acetylcholinesterase

[Display omitted] •The C-g-C3N4 possesses the better conductivity and solubility and was more favorable for chemical modification due to the existence of carboxyl group.•The novel nanocomposite (C-g-C3N4-PEI) possessed excellent luminous efficiency and stability in S2O82− solution.•Based on the C-g-C3N4-PEI-S2O82− ECL system and enzyme inhibition, the fabricated biosensor was developed for ultrasensitive detection of OPs. A signal on electrochemiluminescence (ECL) biosensor was designed for sensitive organophosphate pesticides (OPs) detection based on a novel composite of carboxylated graphitic carbon nitride-poly(ethylenimine) (C-g-C3N4-PEI) and acetylcholinesterase (AChE). The C-g-C3N4-PEI nanocomposite which was prepared through covalent bonding between the COOH of C-g-C3N4 and the NH2 of PEI exhibited significantly enhanced ECL efficiency and stability. K2S2O8 as the coreactant of C-g-C3N4-PEI could be consumed by thiocholine, produced by the hydrolysis of acetylthiocholine (ATCl) in the presence of AChE. Since OPs are one of AChE inhibiter, the consumption of coreactant K2S2O8 decreased with the increasing concentration of OPs, thus enhancing ECL signal. Under the optimum conditions, the proposed biosensor for OPs detection (using ethyl paraoxon as a model OPs) exhibited a wide linear ranging from 1.0 pM to 5.0μM with a low detection limit of 0.3 pM. The novel strategy has the advantages of fine practicality, good stability and reproducibility, which might provide a new promise for OPs detection in real-life samples.