Development And Application Of Electrochemical Sensor Based On Nano-material And Enzymatic Signal Transduction Amplification

Electrochemical biosensors have attracted more attentions because of its high sensitivity,easy operation and good selectivity,which have been applied widely especially for the disease markers detection.In the clinical diagnosis,the traditional electrochemical detection methods can’t meet requirement of the detection because the content of the target is very low.Therefore,the development of new electrochemical signal amplification technology is of great important.Recently,nanomaterials is widely used in electrochemical sensors due to its large surface area,rich surface active center and good biocompatibility.The application of nanomaterials can effectively improve the performance of electrochemical sensors,which as a result improve the sensitivity of the electrochemical sensing.Several electrochemical biosensors based on nanomaterials and enzymatic signal amplification have been proposed for desease biomarkers detection.The detail contents are as follows:1.An electrochemical sensor based on signal conversion amplification strategy was fabricated and applied to the detection of ascorbic acid(AA).The Au-nanoparticles(AuNPs),multi-walled carbon nanotubes(MWCNTs)and polyethyleneimine(PEI)modified glassy carbon electrode(AuNPs/MWNTs/PEI/GCE)was prepared and used as the working electrode which could amplify the electrochemical signal dramatically.The strategy was designed based on the integration of the target triggered silver deposition,the high sensitive metal stripping voltammetric detection and AuNPs induced silver deposition.The presence of AA in detection solution could lead to a rapid silver deposition process on the surface of the AuNPs/MWNTs/PEI/GCE in the presence of Ag+,which could dramatically amplify the electrochemical signal and enhance the detection sensitivity.The present work not only provides a simple platform for ultrasensitive AA detection,but also presents a new signal amplification strategy for electrochemical sensor.2.A highly sensitive electrochemical sensor for ALP detection was designed based on enzyme-induced metallization conversion amplification by combining enzymatic metallization with gold nanoparticle-induced silver deposition.The method used AuNPs/MWNTs/PEI/GCE as working electrode,ALP catalyzed the hydrolysis of L-ascorbic acid 2-phosphate salt(AA-P)to produce a ascorbic acid(AA),AA can reduce Ag+ on the work electrode.As a result the electrochemical signal of ALP could be accumulated on the surface of the working electrode,which amplified the electrochemical signal dramatically.This method combines the specificity of the enzyme catalyzed reaction and the high sensitivity of the electrochemical stripping voltammetry,which effectively the sensitive of ALP detection,which have important significance in cancer diagnosis.3.The electrochemical immunosensor was successfully constructed based on the immunonagnetic separation and multiplex nanogold amplification for sensitive detection of carcinoembryonic antigen(CEA)in this work.Horseradish peroxidase and CEA antibody-labeled bifunctional AuNPs were prepared and used as signal tags.Immunomagnetic beads were used as the carrier of immune reaction to capture CEA,and then formed sanwich typed immunocomplex with bifunctional AuNP probe.The immunocomplex-coated magnetic beads could be captured by magneto electrode to obtain the electrochemical signals.The fouling and passivation of the working electrode by complex samples could be avioded,as a result CEA could be detected with high sensitivity.This method combines the high-efficiency immunomagnetic separation and enrichment,nano-gold multi-labeled amplification,and enzyme catalytic amplification,which amplified the electrochemical signal dramatically.