A novel fluorescent biomimetic sensor based on cerium, nitrogen co-doped carbon quantum dots embedded in cobalt-based metal organic framework@molecularly imprinted polymer for selective and sensitive detection of oxytetracycline

Since oxytetracycline (OTC) residues in foodstuff are very harmful to human health, it is urgent to develop an effective assay to monitor OTC. Herein, an innovative fluorescent biomimetic sensor (Ce, N-CDs@ZIF-67@MIP) based on cerium, nitrogen co-doped carbon quantum dots (Ce, N-CDs) embedded in cobalt-based metal organic framework (ZIF-67) combining with molecularly imprinted polymer (MIP) was triumphantly fabricated by a simple one-pot strategy and subsequently applied for the selective and sensitive detection of OTC. In this strategy, the modification of the surface imprint layer enabled the sensor to possess favorable anti-interference ability and specific recognition performance for OTC. The introduction of ZIF-67 with large specific surface area functioning as supporter significantly increased the mass transfer rate and shortened the response time, which improved the adsorption performance and detection sensitivity of Ce, N-CDs@ZIF-67@MIP. Meanwhile, the Ce, N-CDs featured with bright blue fluorescence (FL) and high fluorescence quantum yield (FLQY, 33.69%) were incorporated as a signal label to make the sensor generate measurable FL response signal according to the inner filter effect (IFE), achieving signal amplification. Thanks to the integrated merits of MIP, ZIF-67 and Ce, N-CDs, the constructed Ce, N-CDs@ZIF-67@MIP sensor not only displayed a favorable linear range (0.05–20 μg mL−1) with a low detection limit (0.015 μg mL−1), but also showed good precision and reproducibility (RSD). More importantly, the designed sensor was successfully used to quantitatively analyze OTC in milk samples, and the corresponding results were in accordance with those obtained by HPLC method. Therefore, the proposed Ce, N-CDs@ZIF-67@MIP sensor is expected to provide an efficient and sensitive FL detection platform for OTC evaluation in dairy products.