Dual-catalytic colorimetric biosensor based on double-active Fe@Co-N stellate porous carbon and DNAzyme for simultaneous detection of tetracycline antibiotics

Colorimetry can identify the detection results visually by a naked eye, but the disadvantages such as low sensitivity and high background signal seriously limit its application prospects. In this paper, we prepared [email protected] stellate porous carbon nanoenzyme with a large specific surface area containing Fe-N and cobalt double peroxide active sites. A dual catalytic system of the nanoenzyme and G-quadruplex/Hemin DNAzyme was constructed, which maintained independent catalytic spaces. And a colorimetric biosensor with a low background signal and ultra-sensitive detection of tetracyclines based on a shared structure was developed. Tetracyclines could adsorb hemin from nearby G-quadruplexes to form multimers that were detached from the system by cyclic shearing of exonuclease I, achieving highly sensitive detection of low concentrations of antibiotics. The limit of detection (LOD) of 0.333 ng/mL (S/N = 3) was much lower than those of most detection methods, indicating the promising strategy could be applied for the simultaneous detection of multiple tetracyclines.