Multi-target photothermal immunochromatography for simultaneous detection of three mycotoxins in foods

Mycotoxin contaminated food poses a threat to human health. On-site detection of mycotoxin contamination is of significance to reduce the agricultural and food industries loss. Lateral flow immunochromatography (LFIC) as on-site detection method for mycotoxins has the advantages of low cost, easy to operate and short time-consuming. Of the various types of LFIC, photothermal LFIC possesses better sensitivity and stronger quantitative capability, but is unable to conduct synchronous multi-target analysis because that the laser can only activate one test area at a time. It was clear that a synchronous multi-target photothermal LFIC method was needed.

In this study, a photothermal LFIC method for the simultaneous detection of three mycotoxins, deoxynivalenol (DON), aflatoxin B₁ (AFB₁) and zearalenone (ZEN), was developed. We broadened the laser source with a beam expander and realized the irradiation and activation of three test zones simultaneously. In addition, the competitive photothermal LFIC was constructed by using Cu_2-xSe-Au nanocomposites with excellent photothermal properties (η = 87.47%) as photothermal signal probes and thermal imager as photothermal signal collector. Under optimized experimental conditions, the limits of detection (LOD) were 73 ng L^-1, 45 ng L^-1 and 43 ng L^-1 for DON, AFB₁ and ZEN, respectively. The method had good linearity in three orders of magnitude and good specificity. The recoveries of the three mycotoxins in oat, cornmeal and millet samples ranged from 78.6% to 112.4%.

Compared with previous studies, this method improved the sensitivity, broadened the linear range of detection without large equipment and realized synchronous multi-target analysis for DON, AFB₁ and ZEN. We addressed a key limitation of photothermal LFIC by a simple way, facilitating the application of this technique in multi-target on-site detection in wider fields.