Molecularly imprinted polymer-based sensor for the determination of 2,4-dinitrophenol in food supplements

The rising demand for weight-loss solutions, driven by obesity concerns and societal pressure, has led to an increasing growth in both the consumption and market of food supplements. However, several studies have identified food supplements as common targets of economically motivated adulteration by the addition of pharmaceutical drugs to enhance the product’s effects. Despite its toxicity and associated health risks, 2,4-dinitrophenol (2,4-DNP) is prone to be illegally added to weight-loss products due to its thermogenic effect, emphasizing the need for reliable detection methods. In this study, we report the first electrochemical sensor integrating a molecularly imprinted polymer (MIP) onto a paper-based platform for the selective detection of 2,4-DNP. This innovative approach combines the high selectivity of MIPs with the cost-effectiveness, portability, and disposability of paper-based devices, paving the way for practical, on-site monitoring of 2,4-DNP in food supplements. The sensor features a paper-based transducer with a gold and carbon ink working electrode that was modified with the MIP, which was synthesized through precipitation polymerization. The sensor's performance was thoroughly evaluated, demonstrating a linear range of 50 - 1000 µmol L -1 and a limit of detection of 16.3 µmol L -1 . The sensor was successfully applied to the analysis of various commercially available weight-loss food supplements (e.g., slimming activators, fat burners, thermoshape) in capsule form, yielding satisfactory recoveries ranging from 85 to 109%. These results highlight the potential of this MIP-based sensor for the rapid, sensitive, and selective determination of 2,4-DNP in food supplements, contributing to consumer safety and regulatory compliance.