An ultrasensitive aptasensor based on self-enhanced Au nanoclusters as highly efficient electrochemiluminescence indicator and multi-site landing DNA walker as signal amplification

Gold nanoclusters (Au NCs) have been shown to be prospective nanoscale electrochemiluminescence (ECL) materials that are being extensively explored in bioanalysis. However, the low ECL efficiency of Au NCs has been a bottleneck barrier for their better bioapplications. To overcome this disadvantage, a low oxidation potential co-reactant N,N-diisopropylethylenediamine (DPEA) was first used to prepare self-enhanced Au NCs (Au-DPEA NCs) for drastically enhancing the ECL efficiency of Au NCs in this study. In addition, an efficient multi-site landing DNA walker with multidirectional motion track and rapid payloads release compared to directional DNA walker was constructed for converting target mucin 1 (MUC1) to intermediate DNA and achieving significant signal amplification. On the basis of the Au-DPEA NCs as efficient ECL signal labels and multi-site landing DNA walker as signal amplification strategy, an ECL aptasensor was established for the ultrasensitive detection of MUC1 in the range from 1 fg mL^-1 to 1 ng mL^-1 with a limit of detection down to 0.54 fg mL^-1. The results demonstrated that the present study opened a new research direction for the development of high-efficiency Au NCs indicator as well as ultrasensitive ECL sensing platform for applications in clinical and bioanalysis.