Selective paper-enhanced infrared spectroscopy for molecular detection of deoxynivalenol in wheat

Mycotoxins are regulated food contaminants, whose occurrence is causing economic and health concerns. To ensure food safety, the monitoring of mycotoxins is of critical importance. Several methods enable rapid screening of mycotoxins on-site; however, they often prevent identifying and quantifying the molecular features of the target analyte. Within these approaches, infrared spectroscopy (IR) is increasingly used to assess the quality and safety of food crops; however, it has not yet shown the sensitivity and selectivity to detect directly mycotoxins in food at relevant legal limits. To overcome this challenge, we here demonstrate an innovative Selective Paper-Enhanced InfraRed Spectroscopy (S-PEIRS) approach to enhance the sensitivity and selectivity of IR spectroscopy and allow molecular recognition of mycotoxins in food. Our methodology leverages immunochemistry and paper microfluidics to selectively hyper-concentrate the mycotoxin molecules on a paper-tip. For the first time, we demonstrate by IR analysis the direct molecular detection of the mycotoxin deoxynivalenol (DON) in naturally contaminated wheat; improving the detection limit of state-of-art IR analysis by a factor 100, from 100 μg∙mL^-1 to 1 μg∙mL^-1. Thus, achieving semi-quantitative analysis in the range of the EU legal limit (1 mg∙kg^-1). Our novel approach demonstrates the potential of paper-based spectroscopic analysis as a general label-free and sensitive tool for the direct molecular identification of contaminants and toxins in food safety.