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Salmonella typhimurium and Listeria monocytogenes are relevant foodborne bacterial pathogens which may cause serious intoxications and infectious diseases in humans. In this study, a sensitive immunochromatographic analysis (ICA) for the simultaneous detection of these two pathogens was developed. For this, test strips containing two test zones with specific monoclonal antibodies (MAb) against lipopolysaccharides of S. typhimurium and L. monocytogenes and one control zone with secondary antibodies were designed, and the double-assay conditions were optimized to ensure high analytical parameters. Prussian blue nanoparticles (PBNPs) were used as nanozyme labels and were conjugated with specific MAbs to perform a sandwich format of the ICA. Peroxidase-mimic properties of PBNPs allowed for the catalytic amplification of the colorimetric signal on test strips, enhancing the assay sensitivity. The limits of detection (LODs) of Salmonella and Listeria cells were 2 × 102 and 7 × 103 cells/mL, respectively. LODs were 100-fold less than those achieved due to the ICA based on the traditional gold label. The developed double ICA was approbated for the detection of bacteria in cow milk samples, which were processed by simple dilution by buffer before the assay. For S. typhimurium and L. monocytogenes, the recoveries from milk were 86.3 ± 9.8 and 118.2 ± 10.5% and correlated well with those estimated by the enzyme-linked immunosorbent assay as a reference method. The proposed approach was characterized by high specificity: no cross-reactivity with other bacteria strains was observed. The assay satisfies the requirements for rapid tests: a full cycle from sample acquisition to result assessment in less than half an hour. The developed ICA has a high application potential for the multiplex detection of other foodborne pathogens. [ABSTRACT FROM AUTHOR]

Salmonella typhimurium and Listeria monocytogenes are relevant foodborne bacterial pathogens which may cause serious intoxications and infectious diseases in humans. In this study, a sensitive immunochromatographic analysis (ICA) for the simultaneous detection of these two pathogens was developed. For this, test strips containing two test zones with specific monoclonal antibodies (MAb) against lipopolysaccharides of S. typhimurium and L. monocytogenes and one control zone with secondary antibodies were designed, and the double-assay conditions were optimized to ensure high analytical parameters. Prussian blue nanoparticles (PBNPs) were used as nanozyme labels and were conjugated with specific MAbs to perform a sandwich format of the ICA. Peroxidase-mimic properties of PBNPs allowed for the catalytic amplification of the colorimetric signal on test strips, enhancing the assay sensitivity. The limits of detection (LODs) of Salmonella and Listeria cells were 2 × 102 and 7 × 103 cells/mL, respectively. LODs were 100-fold less than those achieved due to the ICA based on the traditional gold label. The developed double ICA was approbated for the detection of bacteria in cow milk samples, which were processed by simple dilution by buffer before the assay. For S. typhimurium and L. monocytogenes, the recoveries from milk were 86.3 ± 9.8 and 118.2 ± 10.5% and correlated well with those estimated by the enzyme-linked immunosorbent assay as a reference method. The proposed approach was characterized by high specificity: no cross-reactivity with other bacteria strains was observed. The assay satisfies the requirements for rapid tests: a full cycle from sample acquisition to result assessment in less than half an hour. The developed ICA has a high application potential for the multiplex detection of other foodborne pathogens.

Aquatic toxins are a group of toxic compounds produced by several types of freshwater and marine algae and cyanobacteria and transported through the food chains of water bodies. Potential contamination of aquaculture products (raw and processed fish and seafood) with aquatic toxins requires the use of efficient screening methods for their control. In this study, a multiplex immunochromatographic test system for the simultaneous detection of three aquatic toxins—phycotoxins domoic acid (DA) and okadaic acid (OA), and cyanotoxin microcystin-LR (MC-LR)—is for the first time developed. For this, a competitive indirect immunochromatographic analysis (ICA) based on gold-labeled secondary antibodies was carried out. The LODs/cutoffs/working ranges of the ICA were 0.05/0.3/0.07–0.29, 1.3/100/3.2–58.2, and 0.1/2.0/0.2–1.1 ng/mL for MC-LR, DA, and OA, respectively. The assay duration was 18 min. The developed test system was used to analyze water samples from natural sources (salt and fresh water) and fish samples. For sample preparation of water, simple dilution with a buffer was proposed; for fish samples, methanol–water extraction was utilized. It was demonstrated that the triple LFIA specifically detected target aquatic toxins with recoveries of 85.0–121.5%. The developed multiplex LFIA can be considered a promising analytical solution for the rapid, easy, and sensitive control of water and food safety. [ABSTRACT FROM AUTHOR]