电化学DNA生物传感器定量检测根癌农杆菌终止子基因片段

Electrochemical Deoxyribonucleic Acid Biosensor for Quantitative Detection of NOS Gene Sequence

通过自组装法及共价法固定单链脱氧核糖核酸(ssDNA),制备了电化学DNA生物传感器。将巯基丙酸(MPA)自组装于金电极表面形成单分子膜,再利用1-(3-二甲氨基丙基)-3-乙基碳二亚胺盐酸盐(EDC)和N-羟基琥珀酰亚胺(NHS)的活化作用将ssDNA探针序列固定于金电极表面。将ssDNA修饰的电极与待测溶液中人工合成的转基因食品中常有的根癌农杆菌终止子(NOS)基因片段进行杂交,在[Fe(CN)6]3-/4-溶液中进行循环伏安和电化学阻抗谱扫描,表征ssDNA固定及杂交过程。优化了ssDNA固定条件。待测溶液中DNA浓度在1.0×10-7～1.0×10-10mol/L范围时,其浓度的对数值和ssDNA/Au电极与dsDNA/Au电极峰电流差值的变化值呈线性相关关系,相关系数为0.9822,检出限为8.1×10-11mol/L。

An inexpensive electrochemical DNA biosensor for detection of NOS-terminator Gene Sequence was described. First, a monolayer of 3-Mercaptopropionic acid （MPA） was self-assembled on the gold electrode. Then the single-stranded DNA （ssDNA） was immobilized on gold electrode with the activation of 1-ethyl- 3 （3-dimethyl-aminopropyl） -carbodiimide （EDC） and N-hydroxysulfosuccinimide （NHS）. The ssDNA modified electrode could hybridize with the NOS-terminator Gene Sequence. Electrochemical characterization of the immobilization and hybridization between the probe and target DNA were carried out using cyclic vohammetry （CV） and electrochemical impedance spectroscopy （EIS）. The conditions of ssDNA immobilization were optimized. Under the optimum conditions, the decrease of peak currents for [ Fe （CN）6]^3-/4- redox couple in cyclic vohammetry was correlated to the logarithmic value of target DNA concentration between 1.0 × 10^-7 and 1.0×10^-10 mol/L, the correlation coefficient was 0.9822, and the detection limit was 8.1× 10^-11 mol/L.