A highly sensitive dual-signaling assay via inner filter effect between g-C3N4 and gold nanoparticles for organophosphorus pesticides

With graphitic carbon nitride (g-C3N4) as fluorescent probe, gold nanoparticles (AuNPs) as colorimetric probe, a simple, green, sensitive dual-signaling (fluorometric and colorimetric) detection method for organophosphorus pesticides (OPs) was first constructed. In this method, AuNPs were not only as the colorimetric probes but also as the fluorescent absorbers. The fluorescence of g-C3N4 can be effectively quenched by AuNPs through the inner filter effect. Acetylcholinesterase (AChE) can catalyze acetylcholine (ACh) to product thiocholine, which can result in the aggregation of AuNPs and fluorescent recovery, simultaneously accompanied by a color change from claret-red to blue. When the OPs were introduced, they can irreversibly inhibit the activity of AChE, thus preventing the aggregation of AuNPs and fluorescent recovery. As the typical example of OPs, chlorpyrifos was chosen as the target analyte to demonstrate the possibility of the proposed sensing system. Under the optimal conditions, the linear range of chlorpyrifos was 2.0 x 10(-11) similar to 6.0 x 10(-9) M. Especially, this dual-readout assay was also successfully used for detection of OPs in real samples. (C) 2017 Published by Elsevier B.V.