Fluorescence switching sensor for sensitive detection of sinapine using carbon quantum dots

A new fluorescence switching sensor for sensitive detection of sinapine (SP) was developed based on aggregation and disaggregation of carbon quantum dots (CDs) with the assistance of copper ions (Cu2+). In the detection, carboxyl group on the surface of CDs enables the aggregation triggered by Cu2+ due to the effective coordination, inducing obvious fluorescence quenching. Upon the addition of SP into the solution, higher affinity between SP and Cu2+ is found to from SP-Cu coordination complex, leading to re-dispersion and fluorescence recovery of CDs. The fluorescence switching sensor for SP detection has advantages of simplicity, rapidness, high sensitivity and selectivity. The quantitative range for SP detection is from 0.04 to 5 μg mL−1 with the detection limit of 0.02 μg mL−1. In practical samples, the recoveries of the samples ranged from 87.9% to 117.0%.