[Study of the Detection of Histidine Based on “On-Off” Fluorescence Probe of Carbon Dots]

An new type of switch “On-Off” fluorescence probe was constructed based on fluorescence carbon dots as a novel strategy to analyze trace histidine(His) which was proposed for the first time. In water solution with pH 7.6, the fluorescence of CDs was quenched with Ru3+ due to the formation of ground state compound through electrostatic attraction, and the system was thus “turned-off”. The fluorescence intensity of CDs was “turned-on” due to the competition between His and Ru towards the surface of CDs. The effect of critical parameters including pH, buffer solutions, reaction temperature and time needed to grow the fluorescence intensity of CDs was studied. Results show thatin water solution with pH 7.6, and when the temperature was between 20~25 ℃, the fluorescence intensity of the released CDs displayed a linear relationship in the range of (6.5~219.3)×10-6 mol·L-1 of captopril. Lower limit of detection for His, at the signal-to-noise ratio of 3/(3δ), was 2.15×10-6 mol·L-1. The methodology was successfully applied for the determination of His in Compound Amino Acid Injections, with the RSD≤2.07%, and the recovery rate was between 95.7%～102.4%. The result of the experiment was satisfactory. On the one hand, the excellent optical character CDs was acted as “On-Off” fluorescence probe, which could be extent the application of CDs, on the other hand, the excellent performance of the proposed fluorescence probe shows that this method possesses the potential for practical application.