MultifunctionalDNA Nanonets for a Novel Self-PoweredBiosensor

Multifunctional DNA nanonets were used to design an ultrasensitive self-powered biosensor for tobramycin (TOB) detection based on a bimetallic metal–organic framework, i.e., Fe/Co-MIL-88(NH₂). In the bioanode, Fe/Co-MIL-88(NH₂) shows peroxidase-like activity toward H₂O₂ catalysis and cascades with glucose oxidase to catalyze glucose oxidation. In the biocathode, carbon nanotubes decorated with gold nanoparticles (CNTs@AuNPs) are used to improve the conductivity. When TOB is present, DNA nanonets form double-stranded structures to adsorb [Ru(NH₃)₆]³⁺, amplifying the signal and generating a high open-circuit voltage (<i>E</i>^OCV). Moreover, a capacitor is used to amplify the instantaneous current by storing charges from enzyme biofuel cells. A smartphone allows real-time readout of the test's instantaneous current via Bluetooth technology. The self-powered biosensor exhibits ultrasensitive TOB detection with a limit of detection of 0.41 fM in the range of 1.0–10⁷ fM and possesses excellent selectivity, good stability, high reproducibility, and outstanding applicability to monitor TOB in actual samples.