RESUMO
In this paper, the aluminium-doped carbon dots (Al-CDs) were developed for simultaneous selective detection of five tetracycline antibiotics (TCs), including minocycline (MC), tetracycline (TC), oxytetracycline (OTC), doxycycline (DOC) and chlortetracycline (CTC). With the bright blue fluorescence, Al-CDs displayed excellent stability and showed no obvious fluorescence intensity changes under different ionic strength, acidic or alkaline environment, continuous ultraviolet light illumination, and even longtime storage at room temperature. As adding different antibiotics, the fluorescence of Al-CDs was strongly quenched by five TCs and showed no distinguished changes with the addition of other kinds of antibiotics. The presence of interferential metal ions, anions and small organic molecules imposed no effect on the simultaneous selective detection of five TCs. A good linear relationship was achieved for five TCs in the range of 0-100 µM, and the limit of detection for MC, TC, OTC, DOC, and CTC were 13.91 (0-100 µM), 15.54 (0-100 µM), 14.26 (0-100 µM), 13.48 (0-100 µM) and 13.88 nM (0-100 µM), respectively. Moreover, Al-CDs was successfully used to the detection of five TCs in real samples with recovery ranging from 92.47% to 122.05%, confirming a bright future for the practical applications in the assays of foods, medicines, and environments.
RESUMO
In this paper, a simple and effective fluorescence turn-on approach for highly sensitive and selective monitoring Hg2+ ions was designed by using carbon dots (CDs) and silver nanoparticles (AgNPs). It reveals that the fluorescence of CDs solution can be quenched in the presence of AgNPs through inner filter effect (IFE) and the quenched CDs-AgNPs system is turned on after addition of Hg2+ ions, which is due to higher affinity of Hg2+ and AgNPs than that of CDs and AgNPs, thus resulting the disappearance of AgNPs from the CDs-AgNPs composites and leading to the fluorescence turn-on of CDs. The developed fluorescence turn-on approach exhibited high selectivity and sensitivity for detection of Hg2+. Under the optimum experimental conditions, good linearity was achieved over the range of 100-160 µM and the limit of detection (LOD) was estimated to be 2.22×10-8 M for Hg2+. The recoveries of Hg2+ spiked in real samples ranged from 98.4% to 101.6%. Results of this study suggest that the fluorescence turn-on approach can be used to the detection of Hg2+ in real water samples.