A novel self-powered aptasensor for digoxin monitoring based on the dual-photoelectrode membrane/mediator-free photofuel cell.

Self-powered sensor is considered as a promising, rapid, portable and miniaturized detection device that can work without external power input. In this work, a novel dual-photoelectrode self-powered aptasensor for digoxin detection was designed on the basis of a photofuel cell (PFC) composed of a black TiO ₂ (B-TiO ₂ ) photoanode and a CuBr photocathode in a single-chamber cell. The sensing platform avoided the use of membrane, free mediator, bioactive components and costly metal Pt electrodes. The large inherent bias between the Fermi energy level of B-TiO ₂ and that of CuBr improved the electricity output of PFC that the open circuit potential (OCP) and the maximum power density (P _max ) reached 0.58 V and 6.78 μW cm ^-2 respectively. Based on the excellent output of PFC, digoxin aptamer was immobilized on photoanode as the recognition element to capture digoxin molecules, which realized the high sensitive and selective detection of digoxin. The self-powered aptasensor displayed a broad linear in the range from 10 ^-12  M to 10 ^-5  M with a detection limit (3 S/N) of 0.33 pM. This work paved a luciferous way for further rapid, portable, miniaturized and on-site self-powered sensors.
Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
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