Multiplexed microfluidic fluorescence immunoassay with photodiode array signal acquisition for sub-minute and point-of-need detection of mycotoxins†
Portable, rapid, cost effective and simple analytical tools are in increasing demand to facilitate the routine monitoring of target chemical/biological compounds at the point-of-need. Such devices are highly relevant within the context of food safety, particularly concerning the screening of highly toxic and strictly regulated mycotoxins. To achieve ultrarapid detection of mycotoxins, namely aflatoxin B1, ochratoxin A and deoxynivalenol, at the point-of-need, a novel multiplexed bead-based microfluidic competitive immunosensor, coupled with an array of a-Si:H thin-film photodiodes for integrated fluorescence signal acquisition, is reported. Simultaneously measuring the initial binding rate for each analyte of the sample under analysis against an internal reference, this device provided limits of detection below 1 ng mL−1 for all mycotoxins in a single-step assay and within 1 minute after mixing the sample under analysis with a fluorescent conjugate. The compatibility of the device with the analysis of mycotoxins spiked in corn samples was further demonstrated after performing a sample preparation procedure based on aqueous two-phase extraction. The short times of analysis and sensitivities in the low ng mL−1 range make these devices potentially competitive with the lateral flow devices that are currently the standard for this application. Furthermore, this device architecture and concept is amenable of being expanded to other analytes in food safety, biomedical and other applications.