Incorporating quaternary mesoporous nanospheres and DNA stochastic nanowalkers into a signal amplified switch: A highly sensitive electrochemical assay for APE1

In this work, we engineered a quaternary mesoporous nanosphere by boron- and phosphorus-codoped Pd-Pt alloy (Pd@BP@Pt) to prepare a DNA stochastic nanowalker for catalysis efficiency and local concentration enhancement, which can be applied as an excellent signal amplified switch to electrochemically detect apurinic endonuclease 1 (APE1) with the assist of a highly efficient proximity ligation assay (PLA)-based protein conversion strategy. Specifically, the synthetic Pd@BP@Pt nanomaterial showed excellent catalytic performance for electroactive substances (ferrocene) due to the desirable pore confinement effect and abundant active sites. Moreover, it can be employed to program a DNA stochastic nanowalker to significantly improve the detection sensitivity and response time. In addition, by designing a highly efficient PLA-based protein converting strategy, the target APE1 can be efficiently recognized to concurrently convert APE1 to enormous DNA outputs, which promoted the detection selectivity and sensitivity for APE1 in the range of 1 fg/mL to 1 pg/mL with a detection limit of 0.45 fg/mL. Although the Pd@BP@Pt-based DNA stochastic nanowalker driven by the biological enzyme whose activity may be affected by the environment, the as-prepared electrochemical biosensor based on the Pd@BP@Pt-based DNA stochastic nanowalker has still achieved good detection performance, and possesses enormous potential for the applications of new-type DNA nanomachines in biosensing, bioimaging and clinical diagnosis.