Abstract
A silver nanoparticle (AgNP)-based fluorescence-quenching lateral flow immunoassay with competitive format (cLFIA) was developed for sensitive detection of ochratoxin A (OTA) in grape juice and wine samples in the present study. The Ru(phen)-doped silica nanoparticles (RuNPs) were sprayed on the test and control line zones as background fluorescence signals. The AgNPs were designed as the fluorescence quenchers of RuNPs because they can block the exciting light transferring to the RuNP molecules. The proposed method exhibited high sensitivity for OTA detection, with a detection limit of 0.06 µg/L under optimized conditions. The method also exhibited a good linear range for OTA quantitative analysis from 0.08 µg/L to 5.0 µg/L. The reliability of the fluorescence-quenching cLFIA method was evaluated through analysis of the OTA-spiked red grape wine and juice samples. The average recoveries ranged from 88.0% to 110.0% in red grape wine and from 92.0% to 110.0% in grape juice. Meanwhile, less than a 10% coefficient variation indicated an acceptable precision of the cLFIA method. In summary, the new AgNP-based fluorescence-quenching cLFIA is a simple, rapid, sensitive, and accurate method for quantitative detection of OTA in grape juice and wine or other foodstuffs.
Highlights
The lateral flow immunoassay (LFIA) is a very useful on-site screening method in clinical diagnosis, antiterrorism detection, and environmental and food safety monitoring because it is a low-cost technique for naked-eye detection and it exhibits rapid and simple operation in resource-constrained countries [1,2,3,4,5]
We proposed the use of Ru(phen)23+ -doped silica nanoparticles (RuNPs) as fluorescent donors in the present study
The AgNP probe will migrate on the NC membrane and will be captured by the bovine serum albumin (BSA)–ochratoxin A (OTA) antigen on the T line when an OTA-free sample is applied to the sample well
Summary
The lateral flow immunoassay (LFIA) is a very useful on-site screening method in clinical diagnosis, antiterrorism detection, and environmental and food safety monitoring because it is a low-cost technique for naked-eye detection and it exhibits rapid and simple operation in resource-constrained countries [1,2,3,4,5]. The phenomenon of the inner-filter effect (IFE) will occur when the absorption spectrum of metal nanoparticles overlaps with the fluorescence excitation or emission spectra of fluorescent material [13]. To prove this concept, we proposed the use of Ru(phen)23+ -doped silica nanoparticles (RuNPs) as fluorescent donors in the present study. The 63.6 nm AgNPs were used as the quenchers of the fluorescence of RuNPs. The performance of the AgNP–RuNP–cLFIA sensor was evaluated in terms of specificity, detection limit, linear range, accuracy, and precision for OTA quantitative detection in grape juice and wine samples
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