基于靶序列循环及DNA长距自组装的电化学传感器用于乳腺癌相关序列c-erbB2的检测

Electrochemical Sensor for Detection of Sequence Related to Breast Cancer Based on Target Cycle and Long-range Self-assembled DNA Nanostructures

基于"核酸外切酶(ExoⅢ)辅助靶序列循环"和"DNA长距自组装"两种信号放大技术研制了一种DNA电化学生物传感器,并将其用于乳腺癌相关靶序列的高灵敏、高特异性检测。通过将发卡型探针固定在金电极表面,当靶序列存在时,在ExoⅢ的辅助下,发生杂交、酶降解、再杂交的第一重信号放大过程。接着在电极表面加入两条辅助探针,即可发生级联式杂交,形成长距超级"三明治"DNA结构。该结构可吸附大量的电活性分子六氨合钌配合物(RuHex),产生很强的电化学信号,从而实现信号的第二重放大。实验结果表明,在最佳条件下,该传感器的线性范围为10 amol/L^10 pmol/L,检出限达到8 amol/L,而且能较好地识别完全互补和错配序列,有望用于临床实际样本中超低含量靶序列的检测。

A high sensitive and specific electrochemical sensor based on Exo Ⅲ assisted target cycle and long-range self-assembled DNA nanostructures was developed for the detection of the sequence related to breast cancer. Firstly,a stem-loop hairpin probe was immobilized on the surface of a gold electrode（GE）. In the presence of target DNA,it could switch on a cycle including hybridization,digestion and rehybridization as the first signal amplification. Then the addition of two assisted probes could trigger the formation of super sandwich DNA nanostructures on the electrode surface by long-range self-assembly. The above prepared structure could absorb a large number of electrochemically active molecules RuHex on the surface of GE,resulting in an intense electrochemical response as the second signal amplification. Under the optimum conditions,the sensor showed a good linear relationship in the range of 10 amol / L- 10 pmol / L with a detection limit as low as 8 amol / L. Furthermore,the sensor exhibited an ultra-high discrimination ability even against single-base mismatch sequence. All above properties make it a promising candidate for the ultra-low detection of DNA in clinical real samples.