Copper nanocluster-Ru(dcbpy) as a cathodic ECL-RET probe combined with 3D bipedal DNA walker amplification for bioanalysis.

In this study, a cathodic intra-molecular electrochemiluminescence resonance energy transfer (ECL-RET) probe was exquisitely designed the integration of an ECL donor (Cu NCs) with an acceptor (Ru(dcbpy)), and further employed the 3D bipedal DNA walker amplification strategy to monitor the platelet-derived growth factor BB (PDGF-BB). Specifically, blue emission Cu NCs with low consumption, biocompatibility and numerous resources, act as well-overlapped donors and significantly improve the ECL efficiency of Ru(dcbpy). More impressively, the intra-molecular ECL-RET of Cu NC-Ru endowed a better and more stable ECL signal by reducing the electron-transfer distance and decreasing the energy loss. Furthermore, 3D bipedal DNA walker amplification was employed to efficiently convert the target PDGF-BB into numerous DNA strands, achieving sensitive target amplification. By virtue of such design, the constructed aptasensor exhibited a sensitive and selective assay for PDGF-BB with a detection range from 0.01 pM to 10 nM and a detection limit of 3.3 fM. The intramolecular ECL-RET and 3D bipedal DNA walker amplification strategy designed in this study will provide valuable insight into promising ultrasensitive ECL bioanalysis.