A novel electrochemical sensor based on MWCNTs-COOH/metal-covalent organic frameworks (MCOFs)/Co NPs for highly sensitive determination of DNA base.

• The work employing MWCNTs-COOH, MCOFs and CoNPs to build a sensor was first reported. • The sensor displayed high sensitivity and wide linear range for the simultaneous determination of guanine and adenine. • MCOFs can serve as a promising candidate as modified electrode material. 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. [ABSTRACT FROM AUTHOR]