An "On-Off" self-powered biosensor via GOD activated signal transduction for ultrasensitive detection of multiple biomarkers

A "on-off" self-powered biosensor was developed based on enzymatic biofuel cells (EBFCs) for sequential detection of microRNA-21 (miRNA-21) and miRNA-155 by capture and release of a single-bioanode enzyme, i.e., glucose oxidase. When miRNA-21 is present, it hybridizes with DNA1 and the glucose oxidase (GOD)-modified DNA2, i.e., DNA2-GOD. Then, GOD oxidizes glucose to produce a large number of electrons, and a significantly increased open-circuit voltage (E1OCV) is observed, corresponding to the "on" state. If miRNA-155 is present, it hybridizes with DNA1 and DNA3-functionalized SiO2 nanosphere@gold nanoparticles, i.e., SiO2@AuNPs-DNA3, and replaces miRNA-21 to release GOD at the bioanode, thus leading to decreased E2OCV, corresponding to the "off" state. The "on-off" self-powered biosensor shows ultra-sensitive detection of miRNA-21 and miRNA-155 with detection limits of 0.17 fM and 0.37 fM, respectively. It is believed that this study provides a feasible model for designing self-powered biosensors for multi-targets detection.