Signal-on electrochemiluminescence of biofunctional CdTe quantum dots for biosensing of organophosphate pesticides.

A new, highly sensitive and selective ECL assay biosensor based on target induced signal on has been developed for the detection of organophosphate pesticides (OPs), whereby the smart integration of graphene nanosheets (GNs), CdTe quantum dots (CdTe QDs), and acetylcholinesterase (AChE) enzymatic reaction yields a biofunctional AChE-GNs-QDs hybrid as cathodic ECL emitters for OPs sensing. The electrochemically synthesized GNs were selected as a supporting material to anchor CdTe QDs, exhibiting a significantly amplified ECL signal of QDs. On the basis of the effect of OPs on the ECL signal of AChE-QDs-GNs modified glassy carbon electrode (GCE), a highly sensitive GNs-anchored-QDs-based signal-on ECL biosensor was developed for sensing OPs, combined with the enzymatic reactions and the dissolved oxygen as coreactant. The conditions for OPs detection were optimized by using methyl parathion (MP) as a model OP compound. Under the optimized experimental conditions, such a newly designed system shows remarkably improved sensitivity and selectivity for the sensing of OPs. The detection limit was found to be as low as about 0.06 ng mL(-1) (S/N=3). Toward the goal for practical applications, the resulting sensor was further evaluated by monitoring MP in spiked vegetable samples, showing fine applicability for the detection of MP in real samples.