In-situ nitrogen-doped carbon dots for fluorescence sensing of tetracycline antibiotic

Tetracycline (TET) is one of the common antibiotics used in animal husbandry. However, the long-term consumption of TET may increase the risks for human health, especial in dairy products. Moreover, after entering the human body, TET is difficult to be absorbed by the intestines and stomach, and will be discharged into the sewage in the form of the parent compound, which will cause irreversible damage to the natural environment. Novel nitrogen-doped carbon dots (N-CDs) nanoparticles were successfully fabricated using in situ hydrothermal reaction on the inner surface of the aminated central radial silica spheres (CRSSs-NH2), called CRSSs-NH2@N-CDs. The aminated central radial carrier played a role in protecting and stabilizing N-CDs, thus enhancing it fluorescence and realizing solid-state light emission. The results shown that the optimal excitation wavelength of CRSSs-NH2@N-CDs was about 365 nm, and the emission wavelength was about 446 nm. The CRSSs-NH2@N-CDs was then used as a fluorescent probe for rapidly detecting TET. With optimized experimental conditions, the fluorescence quenching intensity of CRSSs-NH2@N-CDs had a good linear relationship with the concentration of TET. The linear detection range was 0.5–60 μM, and the limit of detection is 0.39 μM. Furthermore, the TET-sensing application in milk has been carried out, and the average recovery range is 91.90%–104.70%.