Label-free homogeneous electrochemical detection of MicroRNA based on target-induced anti-shielding against the catalytic activity of two-dimension nanozyme

Abstract

In traditional homogeneous electrochemical sensing system, methylene blue was stricken with nonspecific intercalation and weak stability, inevitably distorting the diagnosis results. Given the unique catalytic activity of oxidase- and peroxidase-like nanozymes, it is interesting to develop a nanozyme-based homogeneous electrochemical biosensor. Whereas, the preparation of nanozymes with dual enzyme-like activities and two dimensional (2D) morphology is a great challenge. Herein, a soft template-directed wet chemical approach was proposed for preparation of 2D MnO2 nanoflakes, in which the morphology can be easily tuned by the template dosage. Interestingly, not only the oxidase-like activity was discovered, but 2D MnO2 nanoflakes also display a significant peroxidase-like activity. Noticeably, 2D MnO2 nanoflakes exhibit superior response to single stranded deoxyribonucleic acid (ssDNA) over double stranded DNA in the aspect of binding and catalytic activity, which triggers a highly sensitive homogeneous electrochemical detection of microRNA. This study about finding nanozymes with dual enzyme-like activities and ssDNA with inhibiting effect will set up a new avenue to extend the application range of nanozymes and throws a new light on the development of higher-performance electrochemical biosensors.