Abstract
In this study, a fluorometric and colorimetric dual-readout lateral flow immunoassay (LFIA) using antibody functionalized polydopamine-coated gold nanoparticles (Au@PDAs) as a probe was developed for the detection of carbendazim (CBD). Colloidal gold nanoparticles (AuNPs) were coated with polydopamines (PDA) by the oxidation of dopamine to synthesize Au@PDA nanoparticles. The Au@PDA nanoparticles mediated ZnCdSe/ZnS quantum dots (QDs) fluorescence quenching and recovery, resulting in a reverse fluorescence enhancement detection format of CBD. The CBD detection was obtained by the competition between the CBD and the immobilized antigen for Au@PDAs labelled antibody binding, resulting in a significant fluorescence increase and colorimetry decrease corresponded to the concentration of CBD. Dual readout modes were incorporated into the LFIA using the colorimetry signal under natural light and the fluorescence signal under UV light. The cut-off value in the mode of the colorimetric signal and fluorometric signal for CBD detection was 0.5 μg/mL and 0.0156 μg/mL, respectively. The sensitivity of LFIA of the fluorescence mode was 32 times higher than that of the colorimetry mode. There was negligible cross reactivity obtained by using LFIA for the determination of thiabendazole, benomyl, thiophanate-methyl, and thiophanate-ethyl. Consistent and satisfactory results have been achieved by comparing the results of Au@PDAs-QDs-LFIA and liquid chromatography-tandem mass spectrometry (LC—MS/MS) testing spiked cucumber and strawberry samples, indicating good reliability of the Au@PDAs-QDs-LFIA.
Highlights
Carbendazim (CBD) is a widely used fungicide
A highly sensitive antibody functionalized polydopamine-coated gold nanoparticles (Au@PDAs)-quantum dots (QDs)-lateral flow immunoassay (LFIA) was developed based on Au@PDAs
The LFIA was able to rapidly and accurately detect CBD residues in cucumber and strawberry samples, the results of which were verified with liquid chromatography (LC)—mass spectrometry (MS)/MS to prove the reliability
Summary
Carbendazim (CBD) is a widely used fungicide. It is very difficult to degrade naturally due to its stable chemical structure, which leads to a large amount of harmful residues in the environment. The commonly used techniques for the detection of CBD residues mainly include high performance liquid chromatography (HPLC), liquid chromatography-tandem mass spectrometry (LC— MS/MS), liquid chromatography (LC), mass spectrometry (MS), and gas chromatography (GC) [3,4]. Though these instrumental methods provide high accuracy and sensitivity, they require costly equipment, complex sample preparation, long detection time, and skilled operators, which makes them difficult to be used in situ. Lateral flow immunoassays (LFIAs), for instance, are known for their ease-of-use, quick results, and low cost, and have been widely developed for applications in food safety, environment control, and in vitro diagnostics [7–10]. The signal output is one of the key factors that influences the functionality and sensitivity of the rapid immunoassays [20–23]
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