Preparation And Application Of Low-potential Electrochemiluminescence Immunosensor Based On Tris(2,2’-bipyridine)ruthenium(Ⅱ)

Clinical studies have shown that early diagnosis of cancer is of great significance for reducing the mortality of cancer patients and improving the prognosis.At present,the de-tection of tumor markers has shown broad application prospects in the early diagnosis of cancer.Electrochemiluminescence immunoassay technology is the combination of elec-trochemiluminescence and immunoassay.It has the characteristics of strong specificity,good repeatability,and easy automation.It is one of the most advanced labeled immunoas-say techniques and is suitable for the detection of tumor markers.Among many luminous materials,tris（2,2’-bipyridine）ruthenium（Ⅱ）(Ru（bpy）₃²⁺)has at-tracted wide attention due to its good water solubility,high luminous efficiency and elec-trochemical regeneration.However,Ru（bpy）₃²⁺needs to emit light at a high positive or negative potential,which will cause a series of unnecessary side reactions,such as the hy-drogen evolution/oxygen evolution reaction of water and electrochemical damage to the modified electrode and biomolecules.Based on the electrocatalytic activity of gra-phene-ionic liquid-platinum nanocomposite（GN-IL/Pt）,this study developed the lumines-cence of Ru（bpy）₃²⁺at a lower potential and prepared an electrochemiluminescence im-munosensor for the detection of carcinoembryonic antigen（CEA）.The main contents are as follows:1.Construction of carcinoembryonic antigen immunosensor based on low-potential electrochemiluminescence of tris（2,2’-bipyridine）ruthenium（Ⅱ）The experimental results showed that Ru（bpy）₃²⁺can produce strong electrochemilumi-nescence（ECL）on GN-IL/Pt in the potential range of-0.2～0.3 V with sodium oxalate as the co-reactant.The lower luminescence potential is beneficial to the detection of biomol-ecules.Thus,a label-free immunosensor was constructed for CEA detection.In the pres-ence of CEA,the formed immune complex has poor conductivity,which reduces the ECL signal and realizes the sensitive detection of CEA.In the range of 0.1 pg m L^-1～100 ng m L^-1,the ECL intensity of the immunosensor has a linear regression equation is I_ECL=-695.25logc _CEA+12088.79,with the correlation coefficient（R）of 0.9986,the detection limit is 0.01 pg m L^-1（S/N=3）.In addition,the sensor has good specificity,stability and repeatability,with satisfactory results for the detection of actual samples.This work pro-vides a new perspective for the development of a new low-potential excitation ECL system,confirming that the sensing strategy has potential clinical application value.2.Construction of a signal quenching type tris（2,2’-bipyridine）ruthenium（Ⅱ）low-potential electrochemiluminescence immunosensor based on MoS₂ nanoflowersThis experimental results showed that Ru（bpy）₃²⁺can produce stronger ECL on gra-phene-ionic liquid-platinum-palladium nanocomposite（GN-IL/Pt Pd）compared with GN-IL/Pt.This is due to the synergistic effect between Pt and Pd,which enhances the elec-trochemical performance of GN-IL/Pt Pd.At the same time,MoS₂ nanoflowers（MoS₂ NF）were synthesized by hydrothermal synthesis,and it was found that it has a quenching effect on the ECL of Ru（bpy）₃²⁺.Based on this,an immunosensor with a"sandwich"structure was constructed for the sensitive detection of CEA.In the range of 1 fg m L^-1～1 ng m L^-1,the ECL intensity of the immunosensor has a linear relationship with the logarithm of CEA concentration.The linear regression equation is I_ECL=-989.50logc _CEA+10409.93,with the correlation coefficient（R）of 0.9993,The detection limit reached 0.33 fg m L^-1（S/N=3）.The sensor has excellent selectivity,stability and reproducibility,with satisfactory results in the detection of actual sample,and is expected to be used in the clinical detection of CEA.