One-pot target-triggered catalytic DNA assembly for PEC nucleic acid assay based on GDY/CuSe modified electrode

Here, we designed a catalytic DNA assembly (CDA) amplification strategy to construct a photoelectrochemical (PEC) assay to detect the specific target F3L-gene of Monkeypox Virus (MPXV). Graphdiyne (GDY) and CuSe were synthesized by a surface-assisted deprotection/polymerization method and hydrothermal method, respectively. Then AuNPs and GDY/CuSe nanocomposites were modified on the surface of gold electrode (GE). The hairpin DNA4 (H4) was incubated onto the surface of the electrode by Au-S bond. When the target was present, the CDA was occurred by hairpin DNA1 (H1) and hairpin DNA2 (H2). Then, DNA3 (H3) hybridized with the single stranded region of H1-H2 complex, formed a site that can be hydrolyzed by exonuclease III, led to exonuclease III hydrolysis of DNA and to release the H3 primer (H3P). H3 further opened H4 and triggered a subsequent CDA reaction, ultimately formed a Y-shaped DNA structure on the electrode surface with the help of DNA5 (H5) and DNA6 (H6). The two end sequences of H4 and H6, which constituted the Y-shaped structure, were designed as split H3P fragments. They can be used as primers to trigger CDA reactions for more efficient and characteristic autocatalytic signal amplification. The Y-shaped structure carried H5-ALP, and catalyzed phosphonoxyphenol (o-PP) to generate benzene-1,2-diol (CA), which could enhance the PEC signal. The linear range is 0.1 fM-10.0 pM with the detection limit of 0.05 fM (3S/N) for MPXV.