Construction of sandwiched self-powered biosensor based on smart nanostructure and capacitor: Toward multiple signal amplification for thrombin detection

A self-powered electrochemical sensing platform is fabricated to sensitively detect protein based on capacitor signal amplification and one-compartment glucose/O-2 enzymatic biofuel cells (EBFCs). SnS2 nanoflowers/Au nanoparticles (AuNPs) and DNA-carbon nanotubes bioconjugate/AuNPs are prepared and modified on carbon paper as electrode substrates. The sandwiched structure to craft bioanodes is elaborately designed to dramatically enhance the open circuit voltage of the device, triggered by protein coupled with the DNA bioconjugate containing glucose oxidase and aptamer. The EBFCs-based aptasensor will subsequently catalyze glucose oxidation in the presence of the target thrombin (TB). More importantly, a commercial capacitor is also introduced into EBFCs to accumulate charge for a higher instantaneous current. This will result in a significantly amplified readout signal, which can be efficiently captured by digital multimeter. The open circuit voltage can be tuned with target TB concentration ranging from 0.02 to 5 ng/mL with a low detection limit of 7.90 pg/mL. Once the capacitor is charged by EBFCs, a sensitivity of 42.4 mu A/(ng/mL) can be discharged with an increase of 18.4 times than that of pure EBFCs. Furthermore, this capacitor/EBFC hybrid device can be extended as a common platform for the quantitative determination of other proteins and has a great clinical analysis potential.