| Alzheimer's disease is a chronic neurodegenerative disease characterized by problems such as memory loss,decreased speech and direction ability,emotional changes,loss of mobility,and thinking and behavior disorders.In recent years?-amyloid is recognized as a marker of Alzheimer's disease,and the binding of?-amyloid to metal ions such as Cu and Fe has been verified to produce oxidative ROS,produces oxidative damage,which causes great distress to patients.With the development of sensor research,a variety of sensors have been applied to the detection of?-amyloid.In this paper,electrochemiluminescence technology is used as the test method.Using different luminescent substrates,three type sensors are established for?-amyloid detection based on the specificity of aptamers and proteins.This paper mainly consists of the following issues:1)A label-free and signal-on electrochemiluminescence strategy for sensitive amyloid-beta assayA simple,label-free and signal-on ECL aptasensor for specific detection of A?peptide using luminol as ECL emitter and in-situ generated ROS as coreactant via catalytic reaction between Cu2+-A?and the dissolved O2 in the presence of AA.In particular,the aptamer,which was covalently immobilized on gold electrode via the Au–S bond,was used as the probe DNA to bind target A?peptide.Target A?peptide was coordinated with Cu2+to form Cu2+-A?complexes and then the complexes could be recognized by the aptamers immobilized on the electrode.Luminol could generate a strong ECL signal with the assistance of ROS,which was generated in situ via a catalytic reaction between Cu2+-A?-aptamers and the dissolved O2 in the presence of AA.There was an excellent linear relationship between the ECL intensity and the A?monomers concentrations from 1.0×10-13 mol/L to 1.0×10-8 mol/L and the limit of detection was as low as 3.5×10-14 mol/L.This sensor has the characteristics of high sensitivity,good specificity and strong stability.2)Autocatalytic assembly electrochemical luminescence based on g-C3N4-Heme binding to amyloid protein for sensitive detection of?-amyloid protein.The g-C3N4-Heme composite was prepared by hydrothermal synthesis,and the composite was used as the ECL luminescent material.A?and the composite were captured on the electrode through the specific binding of the aptamer to the target and the combination of A?and Heme.Utilizing the light-emitting properties of g-C3N4-Heme and the reaction between g-C3N4-Heme and dissolved oxygen,the formation of a second co-reactant was promoted,and specific detection of A?was finally achieved.In general,the?-amyloid aptamer is immobilized on the surface of the gold electrode through the Au-S bond,and captured on the electrode surface through the specific binding of the aptamer to the target.Heme binds g-C3N4-Heme to the electrode surface.When the sensor combination is completed,the light-emitting and catalytic properties of g-C3N4-Heme are used to detect the A?monomer.In the range of 1.0×10-14mol/L to 1.0×10-7 mol/L,the ECL intensity has a good linear relationship with the logarithm of A?concentration,and the detection limit is as low as 3.2×10-15 mol/L.The sensor has high sensitivity and better specificity.3)Multi-mechanism-driven principle of electrochemiluminescence for highly sensitive detection of?-amyloidA competitively driven electrochemiluminescence sensor was present based on C3N4 as an ECL luminescent substrate.Through the specific binding of an aptamer to a target,the use of A?-Heme-Cu2+will generate H2O2 and steric hindrance to achieve A?monomerspecific detection.Specifically,C3N4 and Au nanoparticles were sequentially assembled on the electrode surface,and the?-amyloid aptamer was immobilized on the surface of the gold electrode through the Au-S bond,and A?-Heme-Cu2+was anchored on the electrode by the specificity of the aptamer and the target assembled on the electrode.When a small amount of A?exists,A?-Heme-Cu2+will produce a small amount of H2O2 to promote the ECL signal of C3N4,the presence of A?-Heme-Cu2+will produce extra steric hindrance to the electrode,resulting in a decrease in the ECL signal.The present sensor has a good linear relationship from1.0×10-13 mol/L to 1.0×10-11 mol/L,and the detection limit is 4.8×10-14mol/L.This method has good sensitivity and selectivity. |
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