An ultrasensitive electrochemical biosensor with amplification of highly efficient triple catalytic hairpin assembly and tetris hybridization chain reaction

In this work, a novel electrochemical biosensor with amplification of highly efficient triple-recycle catalytic hairpin assembly (CHA) and tetris hybridization chain reaction (THCR) was designed for ultrasensitive detection of target ATP. The target-induced triple-recycle could accomplish the highly efficient conversion of limited ATP into plentiful output dsDNA H1-H2 complex owing to the avoiding of waste DNA generation during the whole reaction process. Ingeniously, the THCR triggered by H1-H2 complex produced the tetris and compact DNA nanostructure, thereby providing more binding sites for loading substantial mimicking enzyme manganese porphyrin (MnPP) compared with that of traditional linear structure. Since the MnPP could mimic the catalytic activity of horseradish peroxidase (HRP), a mass of insoluble precipitate benzo-4-chlorohexadienone (4-CD) could thus be in-situ obtained on electrode to hamper electron transfer in the assistant of 4-chloro-1-naphthol (4-CN) and H2O2. As a result, the proposed biosensor showed a linear range from 100 fM to 100 nM and a detection limit down to 30 fM, which provided a new approach for achieving the highly sensitive and selective analysis by using simple and effective amplifying strategy.