Schematic diagram of an amplification-free electrochemical biosensor for detecting F. nucleatum (fadA) based on the CRISPR/Cas system and tetrahedral DNA nanostructures (TDNs). (IMAGE)
Caption
Coralliform gold (CFAu) nanostructures are modifed on the electrode surface by electrochemical deposition followed by immobilizing TDN-ssDNA through sulfur–gold bonding. 3-Mertopropionic acid (MPA) self-assembled monolayer (SAM) is then formed on the electrode surface and the luminescent reagent ruthenium tris(bipyridine) [Ru(bpy)32+] is soft-landed. In addition, ferrocene carboxylic acid (Fc-COOH) is immobilized at the TDN-ssDNA end by amide reaction for quenching Ru(bpy)32+. In the presence of fadA, the trans-cleavage activity of AsCas12a is activated and cleaved fluorescent and tetrahedral probes, resulting in intense electrochemiluminescence (ECL). However, in the absence of fadA, the ECL intensity is very weak. Thus, the specific detection of fadA and F. nucleatum is achieved.
Credit
Jieling Qin, School of Chemistry and Chemical Engineering, Beijing Institute of Technology Zhengzhou Academy of Intelligent Technology, Beijing Institute of Technology
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