Mingyue Wang,Hao Guo,Rui Xue,Qixia Guan,Junye Zhang,Tingting Zhang,Lei Sun,Fan Yang,Wu Yang
Covalent organic frameworks (COFs) offer high surface area, ordered π conjugation system, tunable pore size and structure which are useful for developing electrochemical sensor. However, most COFs were poor conductivity and slow charge transfer rate which restrict their application in electrochemical sensor. Metal-covalent organic frameworks (MCOFs) possess the good electroconductivity and catalytic activity. In addition, the periodic arrays of π clouds of layered 2D structure facilitate charge transport. Here we propose a new strategy to construct a novel electrochemical sensor employing MCOFs (CuP-SQ COF). The fabricated sensor MWCNTs-COOH/CuP-SQ COF/Co NPs/GCE exhibits the excellent performance for the simultaneous determination of DNA base (guanine and adenine) with high sensitivity which can be attributed to the outstanding properties, unique structure and synergistic effect of composites. The wider concentration range of simultaneous quantitive analysis were 0.04 to 130 μM for guanine and 0.06 to 130 μM for adenine . The lower detection limits were 5.5 nM and 7.2 nM (S/N = 3), respectively. This work proves MCOFs can serve as a promising candidate as modified electrode material for developing electrochemical sensor.
Perfluorooctanoic acid (PFOA), a persistent environmental pollutant with severe health risks, demands ultrasensitive detection technologies. Herein, we report a novel label-free photoelectrochemical (PEC) sensor for PFOA based on a metal-bridged self-assembly strategy using nickel-coordinated covalent organic frameworks (Ni-TAPT-Bpy-COF). The Ni(II) centers serve as anchoring points to directionally immobilize perfluorodecanethiol (PFDT) via Ni S bonds, creating a hydrophobic recognition interface. Density functional theory (DFT) calculations reveal that PFDT selectively captures PFOA through fluorine‑fluorine interactions and hydrogen bonding, adopting a head-to-tail staggered conformation that exposes the carboxyl group towards the electrode surface. This orientation impedes electron donor (dopamine) diffusion, enabling PFOA quantification via photocurrent attenuation. To enhance photoelectric conversion, a staggered heterojunction is constructed by integrating nitrogen-doped graphdiyne (N-GDY) with metal-covalent organic frameworks (MCOF), significantly accelerating electron transfer and suppressing carrier recombination. The sensor achieves an ultralow detection limit of 0.031 nM, with high selectivity against structural analogs and inorganic ions. Successful application in tap/lake water samples validates its practicality for on-site monitoring of trace PFOA in complex matrices.
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