Inertial microfluidic-assisted rapid detection of chemical contaminant in foods using quantum dots-based molecularly imprinted sensor

Integration of sample pretreatment, separation and detection in simple steps for food chemical contaminant analysis is challenging due to the complexity of food matrices. A novel analytical approach of using quantum dots-based molecular imprinting fluorescence sensor (QDs@MIPs) combined with inertial separation microfluidic device for separation and detection of enrofloxacin is presented in this study. The microfluidic device was designed based on laminar flow principle combined with Dean-coupled inertial migration of particles in spiral microchannels. Micron-sized QDs@MIPs sensing particles were synthesized for selective separation and sensitive detection of enrofloxacin. Separation of QDs@MIPs was achieved via parallel migration from the original suspension solution to another buffer solution in the same spiral microchannel with a high separation efficiency of 97.7 ± 1.6%. Fluorescence intensity of QDs@MIPs was quenched in the presence of enrofloxacin and showed a linearity in the range of 0.1–50 µg/mL with limit of detection of 0.059 µg/mL. On-chip analyses were performed to detect enrofloxacin in both standard samples and contaminated swine muscle. This microfluidic-assisted fluorescence sensing system provides a solution to integrate sample pretreatment, separation and detection together to realize rapid analysis of food contaminants with high selectivity and sensitivity.