基于碳纳米管修饰的DNA电化学传感器用于大肠杆菌基因片段检测

Determination of E.coli DNA gene fragment by DNA electrochemical aptasensor based on MWCNTs

利用全氟代磺酸脂(Nafion)的成膜效应将多壁碳纳米管(MWCNTs)固定在玻碳电极(GCE)上,制得MWCNTs/Nafion/GCE修饰电极。利用MWCNTs上的羧基和大肠杆菌DNA探针上修饰的氨基之间的酰化反应将探针固定在电极上,大肠杆菌目标DNA与固定于电极表面的DNA探针杂交后,电极表面的电子传递电阻变大,从而实现大肠杆菌目标DNA基因片段的测定。通过电化学循环伏安法(CV)和交流阻抗法(EIS)对所制备的传感器的灵敏度和选择性进行表征,在优化条件下,检测大肠杆菌基因片段的线性范围为10 pmol/L~1.0μmol/L,检出限为6.3 pmol/L,相关系数R2=0.9965。

A sensitive electrochemical impedance spectroscopy(EIS)biosensor was designed for the detection of the target E.coli DNA gene fragment based on the aptamer and carboxylated multi-walled carbon nanotubes(MWCNTs).The adaptor was fixed on the electrode surface according to the acylation reaction with MWCNTs and finally blocking the remaining sites of the modified electrode surface with polyethylene glycol(PEG).In the presence of E.coli DNA,the peak current was decreased and the resistence was increased.Under the optimal conditions,the biosensor had a good response to various concentrations of E.coli gene fragment,and the charge transfer resistance of the sensor was linearly related to the logarithm of adenosine concentrations starting from10 pmol/L to 1.0μmol/L with a detection limit of 6.3 pmol/L.