Detection Of Microquantity Protein And Fabrication Of Folic Acid Microarrays By Scanning Electrochemical Microscopy

Scanning electrochemical microscopy （SECM） was a new scanning probe technologydeveloped at the end of the1980s. Because of its high chemical sensitivity, well spatialresolution, and fast response speed, it had been applied to enzymes, antigens/antbodies, DNAand cell detection, and demonstrated a good prospect. At the same time, various properties andmaterials of ultramicroelectrodes were used as probe of SECM not only improved the detectionsensitivity and resolution of the image, expanded the field toward the application object, but alsoshowed a strong practicality on the surface modification due to the probe could move freelywithin a certain region. Therefore, using the advantages of the SECM in detection and surfacemodification to expand the field of application and solve the problems in the present researchcombined with other technologies was an important direction for future development of theSECM. Here we used the advantages of SECM in detection and surface modification to study thedetection of microquantity protein and fabrication of folic acid microarrays combined with sliverstaining and click chemistry. Some effective results were obtained to provide a foundation for theextending of SECM to the field of food safety.Use SECM as a tool of imaging to detect the protein bands of gel electrophoresis after silverstaining. At first, a SECM detection of microquantity protein method with standard BSA proteinwas established: SDS polyacrylamide gel electrophoresis and silver staining method were usedto separate and detect a series of concentration of BSA. SECM feedback mode principle wasused to image protein bands with different concentrations, especially for the invisiblemicroquantity protein. Then we applied this method to detect allergen protein in milk. Resultsshowed that SECM could detect the level of BSA protein of10^-11g and draw the morphology ofprotein bands by SECM feedback mode principle with a4.2μm radius Pt probe at8.4μm probeheight. This method could be used to detect low content allergen proteins in milk, and thesensitivity was higher than that of the silver staining method. The results suggested that SECMcould be used as a new and sensitive way for detecting microquantity protein.Use SECM as a tool of surface modification to fabricate folic acid microarray on the surfaceof quartz glass plate by catalyst produced by SECM probe and its effective move. Then capturingand fixing the leukemia cell K562with the functionalized surface of folic acid glass plate.Results showed that SECM probe could generate Cu（I） to catalyst the click reaction with thespecial property of Salen Cu（Ⅱ） and the electrochemical characteristic of SECM. Then severaltypes of folic acid microarray were formed on the azide terminated SAMs glass plate. Resultsobserved by optical microscpoe showed that K562could be effectively captured and fixed on thefolic acid functionalized glass plate as the shape of the folic acid microarrays. It suggested thatSECM could successfully be used to fabricate kinds of folic acid microarrays.