基于纳米金和核酸外切酶双重信号放大技术的非标型电化学DNA传感器

his work reports the development of a label-free electrochemical DNA biosensor based on gold nanoparticle and enzymatic dual signal amplifications. In the design, take advantage of the improved mismatch distinguishing ability of MB, the hairpin probe first hybridizes with target DNA to trigger the enzymatic recycling reaction in the presence of exonuclease III, which could avoid the low enzymatic reaction efficiency, effectively. Then, the cleaved sequences hybridize with the hairpin capture probe, which can further improve the mismatch distinguishing ability of the sensing system. Finally, the gold nanoparticles functionalized reporter DNA hybridized with the opened capture probe to amplify the electrochemical signal. Methylene blue was selected as electrically active substances, and the results demonstrated that the presented dual signal amplification strategy was highly sensitive and specific with a detection limit of 0.6 pM for target DNA. The proposed method has many salient advantages, including a simple-to-implement procedure, high sensitivity and specificity, an easy regeneration process and can be used repeatedly with sufficient stability.