Selective detection of melamine using molecularly imprinted plasmonic sensor

Given the severe health risks, including fatalities, associated with the illegal adulteration of food with melamine, it is imperative to develop effective methods for its detection. In this study, a surface plasmon resonance (SPR)-based sensor that more specifically and sensitively determines melamine levels in a single step was fabricated. Melamine-imprinted, and non-imprinted SPR sensors produced using the molecular imprinting technique were characterized by atomic force microscopy, contact angle, and ellipsometry analyses. The melamine-imprinted SPR sensor showed linearity in detecting melamine for the concentration ranges of 0.1–1 ppm (R²: 0.9744) and 2.5–10 ppm (R²: 0.9742) with 0.0031 ppm detection limit. The selectivity of the melamine-imprinted sensor was determined to be 3.19 times higher than that of cyromazine and 5.45 times higher than that of cyanuric acid, both are chosen competitor molecules. Imprinting efficiency was estimated by comparing the melamine-imprinted and non-imprinted SPR sensors, and the imprinting factor value was determined to be 7.04. In the repeatability studies, the melamine-imprinted SPR sensor could detect melamine for five consecutive applications without any deterioration of detection performance (RSD < 1.5). In the repeatability studies, the melamine-imprinted SPR sensor could detect melamine for five consecutive applications without any deterioration of detection performance (RSD < 1.5). Melamine detection sensitivity of the MEL-MIP SPR sensor in milk selected as real samples was tested and verified by HPLC analyses.