Construction And Application Of New Method For Electrochemical Signal Amplification

Electrochemical biosensors have the advantages of strong specificity,high sensitivity,economical and portable methods,which have been extensively studied in analytical chemistry and biomolecular fields.With the development of technology,the electrochemical biosensor sensitivity and material detection limit has a higher demand,which leads to the generation of electrochemical signal amplification techniques.This paper mainly studies the application of nano-materials and nucleic acid amplification technology in electrochemical signal amplification technology,which are summarized as follows:In the first section,the basic principle and classification of electrochemical biosensors were briefly introduced,and the application of several nanomaterials and nucleic acid amplification technology in electrochemical signal amplification technology were reviewed.In the second section,high-quality three-dimensional nanocomposites(Pt nanoparticles anchored on carbon nanocages,Pt/CNCs)were synthesized by a simple chemical approach.PtNPs/CNCs efficiently catalyzed the oxidation of glucose in 0.1 M phosphate buffer solution,and exhibited a rapid response time,a broad linear range,low detection limit,good stability and sensitivity.The electrochemical experiments were performed at a relatively low detection potential,under which the impact from the oxidation of common interfering species could be effectively limited.The superior catalytic activity and selectivity make PtNPs/CNCs nanomaterials promising for direct detection of glucose.In the third section,a new homogeneous electrochemical immunoassay strategy based on combining target-induced proximity hybridization with the rolling circle amplification(RCA)was developed for ultrasensitive detection of carcino-embryonic antigen(CEA).The immobilization-free detection of CEA was realized by use of neutrally charged peptide nucleic acids(PNAs)probe labeled with ferrocene(Fc)as the electroactive indicator on negatively charged indium tin oxide(ITO)electrode surface.The assay showed good selectivity,high sensitivity,acceptable accuracy and satisfactory versatility of analytes,and might be applied to the detection of other biomarkers.In the fourth section,novel hybridization proximity-regulated catalytic DNA hairpin assembly strategy has been proposed for electrochemical immunoassay based on in situ DNA template-synthesized Pd nanoparticles as signal label.Through introducing a supersandwich reaction to increase the DNA length,the electrochemical signal was further amplified and it rendered satisfactory analytical performance for the determination of CEA in serum samples.Furthermore,it exhibited good reproducibility and stability;meanwhile,it also showed excellent specificity due to the specific recognition of antigen by antibody.Therefore,the DNA template synthesized Pd nanoparticles based signal amplification approach has great potential in clinical applications and is also suitable for quantification of biomarkers at ultralow level.