A microfluidic colorimetric immunoassay for sensitive detection of altenariol monomethyl ether by UV spectroscopy and smart phone imaging.

A novel microfluidic colorimetric immunoassay was developed using gold nanoparticles (GNPs) for indicating different concentrations of altenariol monomethyl ether (AME), and UV spectroscopy and smart phone imaging for monitoring color change of the GNPs. Norland Optical Adhesive 81 (NOA 81) was used for simple and rapid fabrication of the microfluidic chip. AME-BSA modified magnetic nanoparticles (MNPs-BSA-AME) were used as capture probe and the self-magnetism for rapid separation and purification. AME monoclonal antibodies modified gold nanoparticles (GNP-mAbs) which dried on conjugate pad were used as detection probe and the self-catalyst for signal amplification. Under the optimal conditions, the proposed microfluidic colorimetric immunoassay was able to detect AME as low as 12.5 pg/mL for UV spectroscopy (574 nm), and 200 pg/mL for smart phone imaging. The total analysis time is less than 15 min. The immunoassay also has a lower cross-reactivity to AME analogues. It was also evaluated by analyzing fruit samples spiked with AME. The recoveries ranged from 91.19% to 94.15% for UV spectroscopy, and from 90.63% to 93.9% for smart phone imaging. This method can be used for rapid, sensitive, low-cost and portable point-of care testing (POCT) of other mycotoxins or haptens in food samples.