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

Guiyun Xu a, Kui Jiaoa,*, Jinshi Fanb, Wei Suna


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

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 5.0×10-91.2×10-7 mol/L.

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