Electrochemical Detection of Specific Gene Related to CaMV35S Using Methylene Blue and Ethylenediamine–modified Glassy Carbon Electrode

^a College of Chemistry and Molecular Engineering, Qingdao University of Science and Technology, 266042 Qingdao, China
^b College of Chemistry and Chemical Engineering, University of Science and Technology, 266042 Qingdao, China

Absrtract
Ethylenediamine (En) was introduced onto an electrochemical oxidized glassy carbon electrode using water-soluble 1-ethyl-3-(3-dimethyl-aminopropyl) carbodiimide hydrochloride (EDC) and N-hydroxysuccinimide (NHS). DNA was then covalently immobilized onto the En modified GCE with surface-bound primary amino group in the presence of EDC. Cyclic voltammetry and differential pulse voltammetry were used to characterize the DNA modified electrodes using methylene blue (MB) as electro-active indicator. The results showed that ssDNA immobilized using ethylenediamine as connector (ssDNA/En/GCE) could hybridize with target ssDNA more effectively than that immobilized directly on the bare GCE (ssDNA/GCE). The ssDNA/En/GCE was successfully employed for the selective detection of CaMV35S gene (presented in almost all the genetically modified plants) in a fragment of 20-base oligodeoxynucleotides sample. The electro-reduction signal of MB was related to the CaMV35S gene concentration over the range of 5.0×10^-9～1.2×10^-7 mol/L.

Keywords: DNA immobilization, ethylenediamine, methylene blue, CaMV35S gene