Application Of Luminol-K₂S₂O₈ Chemiluminescence System In Detection Of Uric Acid And Alkaline Phosphatase

chemiluminescence（CL）is the phenomenon that produced in the process of chemical reaction.Because of the superiorities of simple miniaturized apparatus,no excitation light source and high sensitivity,CL analysis has applied in many fields,such as food analysis,pharmaceutical analysis,molecular biology and clinical diagnosis.At present,luminol,acridine esters and peroxalate esters are commonly used CL reagents.Due to its hydrophilia and high quantum yield,luminol has become the most typical CL reagent.However,luminol involved CL systems has a slow reaction rate and low CL signal,which can not meet the requirements of detection.Hence,it is necessary to add some catalysts to improve the CL emission of the luminol systems.Up to now,the catalysts have gradually changed from metal ions and enzymes to new metal composite materials,metal-organic polymers and nanomaterials.But the synthesis process of these materials always require complicated steps,stringent conditions and longer time.Therefore,simplify the preperation process of catalysts or establish a CL system without catalyst is necessary.In this paper,based on the CL property of the luminol,two simple and efficient CL systems have been established,and the detailed results are summarized as follows:（1）Ag-luminol MOG-K₂S₂O₈ CL system was used to detection of uric acid.Ag-luminol MOG consisting of Ag⁺as ion central and luminol as the ligand was synthesized at room temperature.The morphology and structure of this Ag-luminol MOG was characterized by scanning electron microscopy（SEM）,Fourier transform infrared spectroscopy（FT-IR）,X-ray photoelectron spectroscopy（XPS）and X-ray diffraction pattern（XRD）.The synthesized MOG has a fibrous structure,and the possible aggregation model was proposed.Based on the dual functions of catalyst and luminant of Ag-luminol MOG,a self-enhanced CL system was constructed,in which the interaction between Ag-luminol MOG and K₂S₂O₈ in alkaline condition can emit high-intensity CL signal.The effects of the molar ratio of metal:ligand,p H,concentrations of K₂S₂O₈ and Ag-luminol MOG on the CL intensity of this system were investigated.Meanwhile,the CL mechanism of this Ag-luminol MOG-K₂S₂O₈ system was studied by the results of CL spectra,fluorescence spectra,radical inhibitor experiments and Electron spin resonance（ESR）spectra.Firstly,K₂S₂O₈ can react with H₂O to produce H₂O₂in alkaline condition.Then,as a catalyst,Ag-luminol MOG can catalyze H₂O₂ and K₂S₂O₈ to produce radical oxygen species（ROS）and SO₄^·-,respectively.And most of SO₄^·-can convert to OH^·and further form to ¹O₂ and O₂^·-.Finally,as the luminant,Ag-luminol MOG can be oxidized by ROS to emit strong CL signal.Based on the quenching effect of uric acid（UA）to this CL system,a CL method for UA detection was established with a good linearity over the range from 0.05 to 10μmol·L^-1,and the limit of detection（LOD）was 1.8 nmol·L^-1.In this work,the Ag-luminol MOG was prepared using luminol as ligand,which the preparation process is facile.This Ag-luminol MOG has both catalytic and CL property,which provides a new direction for synthesis of the CL materials with catalytic function.（2）luminol-K₂S₂O₈-H₂O₂ CL system was used to detection of ALP.By mixing luminol,H₂O₂ and K₂S₂O₈ under alkaline condition,a visible blue light can be observed,which lasted for more than 6 hours.The influences of p H and concentrations of luminol,K₂S₂O₈ and H₂O₂ on this CL system were investigated.A possible mechanism of persistent and intensive emission in this CL system was discussed in the context of CL spectra,cyclic voltammetry curve（CV）,ESR spectra,fluorescence and the effects of radical scavengers on luminol-H₂O₂-K₂S₂O₈ system.K₂S₂O₈ and H₂O₂as the co-reactants can promote each other to continuously generate SO₄^·-and ROS(OH^·,¹O₂,O₂^·-),respectively,which can promote to improve the CL emission of luminol.The reaction between K₂S₂O₈ and H₂O can produce H₂O₂,which continuously supplided ROS to this CL system and resulted persistent CL emission.ROS reacted with luminol to generate producing an excited state 3-aminophthalate anions（3-APA*）,producing the intensive and long-lasting CL emission.The signal of this CL system can be quenched via ascorbic acid（AA）,which can be generated through hydrolysis reaction of L-ascorbic acid 2-phosphate trisodium salt（AAP）and alkaline phosphatase（ALP）.Next,a CL-based method was established for the detection of ALP with good linearity from 0.08 U·L^-1 to5 U·L^-1 and the limit of detection was 0.049 U·L^-1.This work provides a new idea for the establishment of long time chemiluminescence system.This thesis focused on the luminol-K₂S₂O₈ systems and designed two CL systems,which required no additional catalysts.The CL mechanism of the Ag-luminol MOG-K₂S₂O₈ system and lumnol-K₂S₂O₈-H₂O₂ system were discussed in detail,and then they were used for the sensitive detection of uric acid and alkaline phosphatase,respectively.This work not only provide a new direction for the development of simple and efficient luminol CL systems,but also give a new idea for the study of long-lasting CL system.