APE1-responsive electrochemiluminescence sensing platform using polymerase/nicking amplification and MXene-assisted signal transduction

A label-free, isothermal, surface-confined electrochemiluminescence assay for apurinic/apyrimidinic endonuclease-1 (APE1) is presented, in which target-triggered isothermal amplification is coupled to a bipedal DNA walker on a PEI-Ru(dcbpy)₃ 2+ /AuNPs@Ti₃C₂ (MXene) transducer to provide high signal with low background. Under optimized conditions, a log-linear range of 1.0 × 10 −3 –1.0 × 10 5  U·L −1 and a limit of detection of 5.62 × 10 −3  U·L −1 were obtained. Applicability in complex media was demonstrated in diluted human serum, yielding recoveries of 96.56–104.51 % with RSD <5 %. Selectivity controls against common nucleases and proteins showed minimal interference, and stepwise electrochemical characterization supported successful interface construction. Feasibility of the nucleic-acid modules and pathway was verified by native and denaturing PAGE, and material identity/localization was corroborated by updated EDS mapping with enhanced Ru/C clarity. By integrating dual amplification on a conductive MXene/Ru interface in a compact, label-free format, this platform enables activity-unit quantitation of APE1 in biologically relevant samples and can be adapted to other DNA-repair enzymes by reprogramming recognition sequences.