“关-开”型碳量子点荧光探针测定左旋多巴的研究

A Carbon Quantum Dots-Based "OFF-ON" Fluorescent Sensor for Sensitive Determination of Levodopa

以淀粉为碳源,通过一步水热法合成了发光性能良好的水溶性碳量子点(CQDs),其荧光量子产率为10%。研究发现,在HCl介质中,将KMnO4加入该CQDs溶液后,CQDs的荧光发生猝灭,体系的荧光信号'关闭';再加入左旋多巴,CQDs的荧光得到恢复,体系的荧光信号呈'打开'状态。据此提出了'关-开'型荧光探针高灵敏检测左旋多巴的新方法。对反应的机理进行初步探讨,考察了各种反应条件,在优化的实验条件下,该CQDs探针的荧光恢复信号值与浓度为1.0×10-7~1.5×10-5 mol/L的左旋多巴呈良好的线性关系,检出限为4.5×10-8 mol/L。该探针用于样品中左旋多巴含量的测定,结果较好。

A new type of water-soluble carbon quantum dots(CQDs)with good luminescence properties has been synthesized by using starch as a carbon source for the detection of levodopa.It was found that in HCl medium,the fluorescence intensity of CQDs was significantly quenched in the prescence of KMnO4,and the fluorescence signal of the system was'closed'.In the prescence of levodopa,the fluorescence of CQDs was recovered,and the fluorescence signal of the system was'opened'.The degree of the recovery of the CQDs fluorescence intensity was proportional to the levodopa concentration.Based on this,a new method for the sensitive detection of levodopa by the'off-on'type fluorescent probe was proposed.The mechanism of the reaction was preliminarily investigated,and various reaction conditions were investigated.Under the optimized experimental conditions,the recovered fluorescence intensity was linearly related with the levodopa concentration in the range of 1.0×10-7 mol/L to 1.5×10-5 mol/L,with a detection limit of 4.5×10-8 mol/L.The method has been successfully applied for the detection of levodopa in samples.