Ultrasensitive photoelectrochemical detection of microcystin-LR based on hybridization chain reaction assisted exciton-plasmon interaction and enzymatic biocatalytic precipitation

Abstract

A competitive photoelectrochemical (PEC) immunosensor for microcystin-LR (MC-LR) detection was developed based on hybridization chain reaction (HCR), exciton-plasmon interactions (EPI) and enzymatic biocatalytic precipitation (BCP) multiple cascade amplification strategy. Firstly, The CdS/Fe2O3 co-sensitized TiO2 nanorod arrays were directly grown on the FTO electrode to immobilize antigens, while Au@polyaniline nanocomposites were used to immobilize secondary antibody as the recognition of MC-LR antibody and a DNA primer as the initiator. Secondly, by using HCR, the DNA chain was associated with streptavidin-labeled alkaline phosphatase decorated gold nanoparticles, which can induce silver metallization on the gold nanoparticles and insoluble biocatalytic precipitation, thus the photocurrent can be changed by energy transfer and the inhibition of electron conduction. Taking the advantage of multiple amplification strategy, the immunosensor showed a linear range from 0.5 ng/L to 100 μg/L with a detection limit of 0.3 ng/L. Moreover, it possessed satisfactory performance of stability, selectivity and reproducibility, thus this PEC immunosensor might be attractive in the field of environmental detection.