In Situ Reduction of Gold Nanoparticle-Decorated Ti₃C₂ MXene for Ultrasensitive Electrochemical Detection of MicroRNA-21 with a Cascaded Signal Amplification Strategy

Sensitive detection of miRNA-21 provides remarkable results for the diagnosis early breast cancer. Here, we fabricated a novel electrochemical biosensor ultrasensitive via in situ reduction gold nanoparticles (AuNPs)-decorated Ti 3 C 2 MXene, combined with cascaded signal amplification strategy, that is, strand displacement DNA walker-induced multi-DNA (product DNA) release and cyclic enzymatic amplification. First, AuNPs on MXene layer was not only used as carrier capture (C-DNA) way to make hybridization accessible but also provide predominant (111) facet high electrocatalytic activity significantly ameliorated signal, which acted both reductant stabilizer. In addition, presence miRNA-21, fragments (p-DNA) were produced by walker could be captured C-DNA trigger Exo III digestion further signals. By amplification, changes peak currents (Δ I ) using differential pulse voltammetry amplified. Under optimal conditions, achieved limit 50 aM (S/N = 3) linear range from 100 1.0 nM. With its excellent analytical performance, this may have potential biomedical applications.