Photoactive conjugated microporous polymer@C60 with quencher on tailed Y-triangular DNA structure for high-performance signal-off photoelectrochemical biosensing.

Herein, we synthesized a conjugated microporous polymer (CMP) decorated C60 (CMP@C60) with high photoelectric conversion efficiency, in which continuously repeated donor-acceptor (D-A) π electron unit within one molecule of CMP on C60 could not only effectively increase the mobility of photogenerated carriers with improved electron transmission, but also constitute the cascade energy band matching with reduced electron-hole recombination. Based on the high-performance of CMP@C60 for producing exciting initial photoelectrochemical (PEC) signal, a sensitive signal-off sensing platform was designed for lead ion (Pb2+) assay by coupling with quencher methylene blue (MB) interacting on efficient long tailed Y-triangular DNA structure (LYTD). The proposed LYTD with a tripod structure could generate six long tails in situ on its side at the same time via a simple hybridization chain reaction (HCR), providing notably grooves on electrode to accommodate quencher MB to significantly depress the signal for sensitive detection of Pb2+. As a result, the proposed PEC biosensor revealed excellent analysis capability with a low detection limit of 0.3 fM (S/N = 3). Additionally, it also showed satisfactory stability in the detection of tap water samples, lake water samples and clinical serum samples, manifesting great application prospect in the areas of environmental pollutant detection.