An enhanced immunochromatography assay based on gold growth on the surface of E. coli carrier for the simultaneous detection of mycotoxins

Abstract

It is desired and urgently needed to improve the sensitivity of immunochromatography assay (ICA) for hazardous chemicals. In this work, an enhanced ICA strip was established and evaluated for simultaneous, semi-quantitative and quantitative detection of ochratoxin A (OTA) and aflatoxin B₁ (AFB₁). The signal strategy based on gold growth on the surface of the E. coli K12 carrier was recommended, which was successfully self-assembled on the enhanced ICA with a double test line pattern. When used as a novel carrier, the E. coli K12 could provide a larger surface area, better biocompatibility and high loading capacity, which was of great help to improve the performance of the ICA. By the naked eye, the semi-quantitative limit of detection (semi-Q-LOD) reached 0.03 ng/mL for both OTA and AFB₁ (17-fold and 33-fold lower than the conventional ICA strip). By the digitized strip reader, the quantitative LODs (Q-LODs) were all identified as 0.01 ng/mL for two mycotoxins (10-fold improvement), with detection ranges of 0.01-0.5 ng/mL for OTA and 0.01-0.2 ng/mL for AFB₁. Furthermore, the high reliability and applicability of the ICA were confirmed by its good correlation with liquid chromatography-tandem mass spectrometry (LC-MS/MS). The advantages of the improved sensitivity, high efficiency and cost savings had been reflected for the ICA. This study could provide an important reference method for the sensitive, simultaneous, rapid and on-site monitoring of multicomponent contaminants.

Keywords: E. coli carrier; Enhanced immunochromatography assay; Gold growth; Mycotoxins; Simultaneous detection.