A new cosensitization photoelectrochemical (PEC) strategy was established by using a donor–acceptor-type photoactive material, poly{4,8-bis[5-(2-ethylhexyl)thiophen-2-yl]benzo[1,2-
b:4,5-
b′]dithiophene-2,6-diyl-
alt-3-fluoro-2-[(2-ethylhexyl)carbonyl]thieno[3,4-
b]thiophene-4,6-diyl} (PTB7-Th), as a signal indicator, which was cosensitized with bis(4,4′dicarboxyl-2,2′-bipyridyl)(4,5,9,14-tetraazabenzo[
b]triphenylene)ruthenium(II) ([Ru(dcbpy)
2dppz]
2+) embedded in the grooves of the DNA duplex and fullerene (nano-C
60) immobilized on the surface of DNA nanoflowers for microRNA assay. [Ru(dcbpy)
2dppz]
2+ and nano-C
60 could effectively enhance the photoelectric conversion efficiency (PCE) of PTB7-Th as a result of well-matched energy levels among nano-C
60, [Ru(dcbpy)
2dppz]
2+ and PTB7-Th, leading to a clearly enhanced photocurrent signal. Meanwhile, a target recycling magnification technique based on duplex-specific nuclease was applied in this work to obtain higher detection sensitivity. The proposed biosensor demonstrated excellent analytical properties within a linear detection range of 2.5 fm to 2.5 nm and a limit of detection down to 0.83 fm . Impressively, this cosensitization PEC strategy offers an effective and convenient avenue to significantly improve the PCE of a photoactive material, resulting in a remarkably improved photocurrent signal for ultrasensitive and highly accurate detection of various targets.
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