Immobilization and hybridization of DNA based on magnesium ion modified 2,6-pyridinedicarboxylic acid polymer and its application for label-free PAT gene fragment detection by electrochemical impedance spectroscopy  

作　　者：JIAO Kui YANG Tao YANG Jie FENG YuanYuan 

机构地区：[1]College of Chemistry and Molecular Engineering,Qingdao University of Science and Technology,Qingdao 266042,China

出　　处：《Science China Chemistry》2007年第4期538-546,共9页中国科学（化学英文版）

基　　金：Supported by the National Natural Science Foundation of China (Grant Nos. 20635020 and 20375020);Doctoral Foundation of the Ministry of Education of China (Grant No. 20060426001);the Natural Science Foundation of Qingdao City (Grant No. 04-2-JZP-8)

摘　　要：A new approach for a simple electrochemical detection of PAT gene fragment is described. Poly(2,6-pyridinedicarboxylic acid) (PDC) modified glassy carbon electrode (GCE) was prepared by potential scan electropolymerization in an aqueous solution. Mg2+ ions were incorporated by immer-sion of the modified electrode in 0.5 mol/L aqueous solution of MgCl2 to complete the preparation of a generic "activated" electrode ready for binding the probe DNA. The ssDNA was linked to the conduct-ing polymer by forming a bidentate complex between the carboxyl groups on the polymer and the phosphate groups of DNA via Mg2+. DNA immobilization and hybridization were characterized with dif-ferential pulse voltammetry (DPV) by using methylene blue (MB) as indicator and electrochemical im-pedance spectroscopy (EIS). The EIS was of higher sensitivity for DNA detection as compared with voltammetric methods in our strategy. The electron transfer resistance (Ret) of the electrode surface in EIS in [Fe(CN)6]3-/4- solution increased after the immobilization of the DNA probe on the Mg/PDC/GCE electrode. The hybridization of the DNA probe with complementary DNA (cDNA) made Ret increase further. The difference between the Ret at ssDNA/Mg/PDC/GCE and that at hybridization DNA modified electrode (dsDNA/Mg/PDC/GCE) was applied to determine the specific sequence related to the target PAT gene with the dynamic range comprised between 1.0 × 10-9 and 1.0 × 10_5 mol/L. A detection limit of 3.4 × 10-10 mol/L of oligonucleotides can be estimated.A new approach for a simple electrochemical detection of PAT gene fragment is described. Poly(2,6-pyridinedicarboxylic acid) (PDC) modified glassy carbon electrode (GCE) was prepared by potential scan electropolymerization in an aqueous solution. Mg2+ ions were incorporated by immersion of the modified electrode in 0.5 mol/L aqueous solution of MgCl2 to complete the preparation of a generic “activated” electrode ready for binding the probe DNA. The ssDNA was linked to the conducting polymer by forming a bidentate complex between the carboxyl groups on the polymer and the phosphate groups of DNA via Mg2+. DNA immobilization and hybridization were characterized with differential pulse voltammetry (DPV) by using methylene blue (MB) as indicator and electrochemical impedance spectroscopy (EIS). The EIS was of higher sensitivity for DNA detection as compared with voltammetric methods in our strategy. The electron transfer resistance (R et) of the electrode surface in EIS in [Fe(CN)6]3?/4? solution increased after the immobilization of the DNA probe on the Mg/PDC/GCE electrode. The hybridization of the DNA probe with complementary DNA (cDNA) made R et increase further. The difference between the R et at ssDNA/Mg/PDC/GCE and that at hybridization DNA modified electrode (dsDNA/Mg/PDC/GCE) was applied to determine the specific sequence related to the target PAT gene with the dynamic range comprised between 1.0 × 10?9 and 1.0 × 10?5 mol/L. A detection limit of 3.4 × 10?10 mol/L of oligonucleotides can be estimated.

关 键 词：2 6-Pyridinedicarboxylic acid DNA differential pulse VOLTAMMETRY electrochemical impedance spectroscopy PAT gene 

分 类 号：Q78[生物学—分子生物学]