Construction And Application Of Label-free Electrochemiluminescence Biosensor Based On Nanomaterials

In recent years,Electrochemiluminescence（ECL）has been widely used in the field of biological analysis due to its high sensitivity and low detection limit.Nanomaterials have good biocompatibility,excellent electrochemical and catalytic performance.The use of nanomaterials as an ECL sensor platform can not only immobilize a large number of biomolecules,but also improve the performance of sensors and achieve ultra-sensitive detection of biomolecules.In this paper,Au-Co/GO,Au-Ag/g-C₃N₄ and CdS QDs@MOF nanocomposites were successfully synthesized and label-free ECL biosensors were used to detect glucose and carcinoembryonic antigen（CEA）based on these nanocomposites as sensing platforms.The main research contents are deseribed as follows:（1）A novel ECL glucose oxidase（GOD）sensor was constructed based on Au-Co/GO nanocomposites and used to detect glucose.The Au-Co/GO nanocomposites were synthesized by one-step in-situ chemical reduction method for the first time and the materials were characterized by different technique.The results showed that the synthesized Au-Co nanoparticles were bimetallic alloys with a particle size of about 4 nm and uniformly dispersed on the GO nanosheets.ECL results indicated that GO nanosheets and Au-Co alloy nanoparticles had synergistic effect on enhancing the ECL of Luminol-H₂O₂ system.Further,the GOD was immobilized on the electrode to achieve sensitive detection of glucose.The detection range of glucose was from 1μM to 100μM and the limit of detection was 0.18μM,Moreover,this proposed sensor exhibited good stability,selectivity and was successfully used for the detection of glucose in human serum.（2）A novel label-free ECL sensor was constructed based on a resonance energy transfer system between CdS QDs@MOF nanocomposites and Ru（bpy）₃²⁺for the detection of CEA.CdS QDs@MOF acted as a donor and Ru（bpy）₃²⁺acted as an acceptor.In addition,CdS QDs@MOF was also employed as a co-reactant for Ru（bpy）₃²⁺to enhance the ECL signal of the system.Further modified TEOA@Au nanoparticles for immobilization of CEA aptamers,and triethanolamine（TEOA）as a co-reactant of Ru（bpy）₃²⁺can amplify the ECL signal of the system to improve sensitivity and linear range of CEA.The linear range of the sensor for CEA detection was from 100 fg·mL^-1 to 10 ng·mL^-1,and the detection limit was 85 fg·mL^-1.Satisfactory results had been obtained in experiments for detecting CEA in human serum.（3）A label-free ECL aptamer sensor was successfully constructed using the synthesized Au-Ag/g-C₃N₄ nanocomposites as a sensing platform for detecting CEA.On the one hand,Au-Ag/g-C₃N₄ nanocomposites had good biocompatibility,a large number of CEA aptamers can be immobilized by Au-S or Ag-S bonds.On the other hand,Au-Ag/g-C₃N₄ had excellent catalytic performance and can efficiently catalyze the reduction of dissolved oxygen to produce reactive oxygen species,thereby enhanced the ECL strength of Luminol-H₂O₂ system and improved the performance of the sensor.Under the optimal experiment conditions,the detection range of CEA was from 1 fg·mL^-1 to 1 ng·mL^-1,and the detection limit was 0.89 fg·mL^-1.In addition,the strategy had good stability,selectivity,and satisfactory results had been obtained in the test of CEA in human serum.