A portable integrated magnetic solid-phase extraction device combined with an enzyme-catalyzed colorimetric lateral flow aptasensor for on-site detection of ochratoxin A.

Ochratoxin A (OTA) poses significant health risks and is prevalent in various plant-based foods, necessitating rapid and reliable on-site detection methods. In this study, a lateral flow aptasensor integrating magnetic solid-phase extraction (MSPE) with enzyme-catalyzed colorimetric signal transduction was developed for the rapid determination of OTA. To facilitate field deployment, a portable integrated MSPE device featuring adjustable rotation speed and duration, as well as automated magnetic separation, was designed to enable efficient sample pretreatment under on-site conditions. Polydopamine-coated magnetic beads were employed for MSPE due to their suitability for batch sample processing. Moreover, enzyme-catalyzed colorimetry was introduced as an alternative signal transduction strategy in lateral flow assays. The proposed aptasensor exhibited good specificity and satisfactory sensitivity, with a limit of detection of 0.30 ng/mL. Acceptable accuracy and precision were achieved, with recoveries of 91.1-97.2% and relative standard deviations below 15%. The method was further validated by analyzing commercially available food samples, with results showing good agreement with the standard HPLC method. This integrated strategy enables reliable on-site detection of OTA in complex food matrices by combining efficient magnetic sample pretreatment with enhanced enzyme-catalyzed colorimetric signal transduction.