Rational Engineering of the DNA Walker Amplification Strategy by Using a Au@Ti₃C₂@PEI-Ru(dcbpy)₃²⁺ Nanocomposite Biosensor for Detection of the SARS-CoV-2 RdRp Gene

The detection of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is crucial for preventing and controlling infectious diseases and disease treatment. In this work, a Au@Ti3C2@PEI-Ru(dcbpy)32+ nanocomposite-based electrochemiluminescence (ECL) biosensor was rationally designed, which realized sensitive detection of the RNA-dependent RNA polymerase (RdRp) gene of SARS-CoV-2. In addition, a DNA walker was also used to excise the hairpin DNAs under the action of Nb.BbvCI endonuclease. Furthermore, model DNA–Ag nanoclusters (model DNA–AgNCs) were used to quench the initial ECL signal. As a result, the ECL biosensor was used to sensitively detect the SARS-CoV-2 RdRp gene with a detection range of 1 fM to 100 pM and a limit of detection of 0.21 fM. It was indicated that the ECL biosensor had a great application potential for clinical medical detection. Furthermore, the DNA walker amplification also played a reliable candidate strategy for other detection methods.