Flow-Through Aptamer-SERS Microfluidic Platform for Aflatoxin B1 Detection in Food Crops

Mycotoxins are secondary metabolites produced by fungal species. Due to its high toxicity, Aflatoxin B1 (AFB1) is one of the most hazardous mycotoxins found in various food crops. The ability to detect such a toxin is therefore important for the safe consumption and handling of large quantities of crops. For this, surface-enhanced spectroscopy provides the sensitivity to detect low concentrations of analytes but is limited in terms of specificity toward a given analyte. This work explores how to enhance the selectivity of a SERS active platform by conjugating it with aptamers designed to specifically recognize AFB1 target molecules. A robust flow-through lab-on-a-chip platform with an integrated SERS gold nanohole array functionalized with an aptamer (apta-SERS) was developed and tested on real samples, demonstrating rapid, high-affinity toxin detection. The sensitivity of the nanoholes was evaluated in the range of 10-700 ppb, and in the presence of a complex matrix such as food crop extracts, a limit of detection of 10 ppb was reached. Such a platform enables in situ AFB1 detection through SERS-enhanced aptamer recognition that forms a hairpin loop secondary structure around AFB1. The developed microfluidic platform minimizes direct contact with contaminated samples, and results are highly selective and reproducible, making it promising for other portable toxin-detection applications.