Engineering a high-efficient DNA amplifier for biosensing application based on perylene decorated Ag microflowers as novel electrochemiluminescence indicators.

DNA-based amplifiers with high programmability and accurate molecular recognition ability have become a versatile platform for target amplification. However, the random diffusion of capture probes (CPs) in most DNA amplifiers limits the target recognition efficiency, affecting the limit of detection. Herein, a high-efficient DNA amplifier was developed by localizing the CPs consisted of the unique palindromic tails and target recognition sequences on Au nanoparticle modified magnetic beads (Au@MBs). In the presence of target K-ras gene, the CPs with high local concentration and orientation could capture the target efficiently to expose their palindromic tails, which could act as primers to trigger the polymerization for target recycling. More importantly, the polymerization products could involve in the next recycle and produce abundant mimic targets (MTs) continuously, thereby achieving the detection of trace K-ras gene. Meanwhile, a novel electrochemiluminescence (ECL) indicator of a thin-layer of perylene (Pe) molecules decorated Ag microflowers (Pe@Ag MFs) was obtained based on the reaction between the perylene cation radical (Pe) and Ag atoms. The obtained Pe@Ag MFs exhibited desirable ECL performance because (i) a thin-layer of Pe molecules could reduce the inner filter effect and inactive emitters, (ii) the Ag MFs as coreaction accelerator could react with SO to produce more SO and shorten the distance between Pe and SO to significantly enhance the ECL intensity of Pe with less energy loss. This work paves the way for the development of efficient amplification strategy and offers a paradigm for the preparation of high-efficiency ECL indicators.