Chemiluminescence Of Nitrogen Silver Doped Carbon Dots And Its Application

Chemiluminescence（CL）has become one of the important methods in trace analysis because of its simple instrument,no interference of background light source,wide linear range and sensitivity.It is widely used in food safety,bioscience and other fields.The traditional CL system often have weak stability and poor selectivity in practical application,which limits its further use.Obtaining high CL intensity is the key for CL sensitive analysis.However,some CL reactions emit low light intensity,and can not meet the sensitivity requirements of CL method.In order to further broaden the analytical application of CL method,it is urgent to find suitable nano materials to maximize CL intensity.Carbon dots（CDs）have attracted extensive research interest because of their low toxicity,excellent optical properties and good biocompatibility.In CL analysis,CDs can participate in CL system as illuminant,energy receptor or catalyst,which greatly improves the sensitivity of CL reaction and widens the application range of CL analysis.In this paper,nitrogen and silver doped carbon dots（N,Ag-CDs）were synthesized by one-step hydrothermal method and applied to different CL systems.The main research results are as follows:1.Studies have shown that under alkaline conditions,N,Ag-CDs would produce a higher CL intensity in the K₃Fe（CN）₆-H₂O₂ system,which may be due to the role of N,Ag-CDs as energy acceptors and emitters in the system.The addition of Cu²⁺would significantly reduce the CL intensity of the N,Ag-CDs-K₃Fe（CN）₆-H₂O₂ system,which may be because Cu²⁺would react with N,Ag-CDs,and other metal ions at the same concentration had no obvious effect with N,Ag-CDs.With the increase of Cu²⁺concentration,the CL intensity decreased.Based on this phenomenon,a method for the determination of Cu²⁺in plasma,tea and water samples was established.Under the optimum conditions,the linear range of Cu²⁺determined by N,Ag-CDs-K₃Fe（CN）₆-H₂O₂ system was 0.04-8.0μM,and the detection limit was 31.0nM.2.A simple,rapid and environment-friendly method for the detection of Co²⁺was established by using N,Ag-CDs-H₂O₂ system.The CL intensity increased linearly with the increase of Co²⁺concentration.The N,Ag-CDs-H₂O₂ system could detect Co²⁺in the linear range of 0.4-40.0μM with a detection limit of 69.0 nM.The system could be used to detect Co²⁺in vitamin B12 tablets and egg yolk.Hydroquinone（HQ）could react with H₂O₂ to reduce N,Ag-CDs-H₂O₂-Co²⁺system CL intensity,and a new CL sensor was established to effectively detect the content of HQ in water samples.The linear range of HQ detection was0.2-20.0μM.The detection limit was 42.0 nM.The method is simple,sensitive and selective and is an important tool in analysis.3.The reaction between N,Ag-CDs and KMnO₄ could generate CL,and the addition of HCHO accelerated the redox reaction rate of N,Ag-CDs-KMnO₄ and enhanced the CL intensity.Based on this,the N,Ag-CDs-KMnO₄-HCHO system was constructed.Studies have shown that tannins（TA）could inhibit the CL intensity of N,Ag-CDs-KMnO₄-HCHO system.Under the optimal experimental parameters,a working curve of TA in the concentration range of 0.4-10.0μM was established with a detection limit of 43.0 nM.The method was successfully applied to the determination of TA content in red wine and tea,and the recovery rate was 98.6%-104.9%,the results were satisfactory.In addition,the possible mechanism of the CL reaction was discussed according to the CL spectrum and UV-vis spectrum.