Detection of penicillin G residues in milk based on dual-emission carbon dots and molecularly imprinted polymers

Instant detection of antibiotic residues in dairy products has been remained a challenge. Current methods require careful samples storage and handling, skilled personnel, and expensive instrumentations. Herein, we report the preparation of a ratiometric fluorescent sensor that contains different colored Carbon dots (CDs) as dual fluorophores, and a mesoporous structured molecularly imprinted polymer as a receptor (B/YCDs@mMIP) for penicillin-G (PNG) detection in milk. Upon PNG addition, only the fluorescence of yellow emissive CDs was quenched due to analyte blockage, while that of the blue emissive CDs stayed almost constant, which led to an obvious change in the fluorescence color from the yellow to blue. A linear response in the range of 1-32 nM with a detection limit of 0.34 nM and excellent recognition specificity for PNG over its analogs were also observed. Comparing our sensor with its counterparts, it exhibited a promising potential in the in-situ PNG detection in milk.