Luminol-reduced Au nanoparticles-based dual-signal immunochromatographic test strip for pesticide residues

Abstract

Luminol-reduced Au nanoparticles (AuNPs) were prepared by using a facile one-step method. Luminol-reduced AuNPs were utilized as a novel dual-readout probe to develop a qualitative/quantitative immunochromatographic test strip (ITS) for detecting pesticide residues, by adopting fenvalerate as a model analyte. Fenvalerate in sample solution could compete with its corresponding immobilized coating antigen in test line of ITS to bind the AuNPs-tagged fenvalerate monoclonal antibody. After the complete immunoreaction, the AuNPs-tagged antibody in test line was the dual-readout probe. Superior to signal readout-based ITSs, especially traditional Au nanoparticles-based ITSs, luminol-reduced AuNPs-based dual-readout ITSs could simultaneously meet the demand of qualitative analysis and quantitative detection. Colorimetric signal from luminol-reduced AuNPs could be adopted as a qualitative readout, which could increase analysis efficiency in field analysis and rapid testing. In the proposed analytical platform, fenvalerate could be semi-quantitated within 15 min. Furthermore, as for affirmed contaminated sample through colorimetric analysis, chemiluminescent (CL) signal originating from luminophor-modified AuNPs as a quantitative readout aided to improve analytical sensitivity after triggering luminol-H2O2 CL reaction. Under the optimal conditions, the detection limit for fenvalerate were 0.067 ng/mL (S/N = 3). The reliability of dual-readout ITSs was demonstrated through the successful practical application on traditional Chinese medicines. Owing to high analysis efficiency, low cost, high facility and improved accuracy, the dual-readout ITSs by using only one probe showed great potential in field analysis and rapid testing for drug safety, environmental sanitation and clinical diagnosis.