Construction of carbon quantum dots/riboflavin fluorescent probe and its application in the detection of ciprofloxacin

Abstract This paper synthesized blue-fluorescent carbon quantum dots (b-CQDs) using a hydrothermal method, in which passionfruit shells is used as the carbon source and diethylenetriamine is used as the nitrogen source. The average particle size of the b-CQDs is 3.29 nm, and the quantum yield is 19.6%. Riboflavin was added to the CQDs to form a fluorescent probe with double emission peaks at 445 and 510 nm, belonging to b-CQDs and riboflavin, respectively. Their physical structure and optical properties were investigated by a series of characterizations. The results show that b-CQDs have good fluorescence stability. An experimental analysis showed that the addition of ciprofloxacin (CIP) to the fluorescent probe can significantly enhance the emission peak at 445 nm, whereas the emission peak at 510 nm remains unchanged. Accordingly, we constructed a ratio fluorescence method using b-CQDs/riboflavin as the fluorescent probe to detect CIP. In the water system, the I 445 nm /I 510 nm ratio of the fluorescent probe has an obvious linear relationship with CIP at a concentration of 0–250 µmol·L − 1 . The linear equation obtained by fitting is I 445 nm /I 510 nm = 0.0028C CIP + 1.1510, where the correlation coefficient R 2 is 0.9961 and the detection limit is 0.86 µmol·L − 1 .