Cascade-Enhanced Lateral Flow Immunoassay for Sensitive Detection of Okadaic Acid in Seawater, Fish, and Seafood

Abstract

In this investigation, a new approach for developing a sensitive lateral flow immunoassay (LFIA) was proposed for the detection of the hazardous marine toxin okadaic acid (OA). It is based on the indirect format with anti-species antibodies labeled by gold nanoparticles (AuNPs) and cascade signal amplification. The latter is performed by first passing a mixture of anti-OA antibodies and a tested sample along the immunochromatographic test strip and then performing several cycles of the interaction of anti-species antibodies conjugated with AuNPs with free antibodies, which bind to anti-species antibodies but are not specific to the target analyte. As a result, branched aggregates are formed, due to which the colorimetric signal intensification occurs. The developed test system enabled the detection of OA with an instrumental detection limit of 30 pg/mL and a cutoff of 1 ng/mL, which exceeds these characteristics in the LFIA without amplification by 7 and 2 times, respectively. The OA recoveries from seawater, fish, and seafood varied from 76.9% to 126%. The test system may be required for point-of-care monitoring of samples for phycotoxin contamination; the developed principle of signal amplification can be used in cases where highly sensitive detection of trace amounts of a contaminant is required.

A Sensitive Fluorescence Polarization Immunoassay for the Rapid Detection of Okadaic Acid in Environmental Waters

“…In general, LODs of OA are lower in ELISAs, approximately reaching picogram values [ 38 , 39 , 40 , 41 , 42 , 43 , 44 , 45 , 46 , 47 ]. In ICAs [ 44 , 45 , 46 , 47 , 48 , 49 ], including multiparametric ones [ 18 , 20 , 50 ], the sensitivity of the determination is somewhat worse (up to the nanogram concentration range), and improvements in this method were achieved with amplification approaches aimed at increasing analytical signal [ 19 , 51 ]. The duration of the analysis in the case of ICA is 10–40 min.…”

Application of Au@Pt Nanozyme as Enhancing Label for the Sensitive Lateral Flow Immunoassay of Okadaic Acid

“…The developed enhanced LFIA was tested for the determination of OA in real samples, which included seawater, river water, and fish (trout) samples. The sample preparation was developed in our previous studies [ 19 , 20 , 21 ]. The absence of OA in the tested samples (before spiking) was confirmed by the ELISA using OA ELISA kits (EuroProxima, Arnhem, The Netherlands).…”

“…Our previous investigations in this field were aimed at multiplex determination of OA, domoic acid, and microcystin-LR as representatives of DSP, amnestic shellfish poisoning toxins, and hepatotoxins, respectively [ 19 , 20 ]. Besides, the enhanced LFIA of OA with cascade signal amplification was implemented [ 21 ].…”

Visual Detection of Chicken Adulteration Based on a Lateral Flow Strip-PCR Strategy

“…The colloidal gold solution remains red when the protein labeling amount is 20 µg and 25 µg ( Figure 4 A). Insufficient amounts of protein will lead to colloidal gold particle surface instability to cause aggregation, which can be seen as colloidal gold solution from red to blue [ 35 ]. Therefore, 20 µg of streptavidin is sufficient to stabilize 1 mL of colloidal gold solution, which can be appropriately increased by 10% as the optimum protein labeling amount in practice.…”