Preparation of carbon quantum dots from lycium chinensis and as a fluorescent probe for high sensitive detection of <italic>D</italic>-penicillamine

Abstract

A one-step hydrothermal method was developed for the preparation of carbon quantum dots (CQDs) with strong fluorescence by using lyciumchinensis as precursors, and a turn-on fluorescent probe based on Cu(II) forming radiation free complex to CQDs was developed for detection of D-Penicillamine ( D -PA) with high sensitivity and selectivety. After Cu(II) ions were added in CQDs solution, the fluorescence of CQDs was quenched, and the fluorescence signal of the system is in the “off” state. In the presence of D -PA, a more stable complex than the CQDs-Cu(II) complex was formed due to D -PA and Cu(II) have a stronger binding force, which result in the departure of Cu(II) from the surface of the CQDs, and the fluorescence signal of the system was “open”. The mechanism of fluorescence quenching of CQDs by Cu(II) was studied, and the reaction conditions were optimized. Under optimal conditions, the fluorescence recovery degree of the CQDs probe showed a good linear relationship with the concentration of D -PA from 0.5 to 80 μmol L−1. The limit of detection was estimated to be 0.15 μmol L−1. The present method was successfully applied for the detection of D -PA in human serum. Recoveries were found to be in the range of 96.7%‒105%, and the result of statistical calculation shows that relative standard deviations (RSDs) were lower than 3.1%. These results indicate that present method can be applied for the detection of D -AP in the human serum and pharmacokinetics investigation of D -AP.