DNA nanostructure assembly via super-intercrossed hybridization chain reaction for ultrasensitive dual-mode biosensing

Hybridization chain reaction provides a useful approach to construct DNA nanostructures for electrochemical biosensing. However, most of them rely on various linear DNA assembly reactions. Herein, we design a novel super-intercrossed hybridization chain reaction (SC-HCR) for efficient assembly of a stable DNA nanostructure, thus developing an electrochemical/fluorescence dual-mode biosensing method for kanamycin (Kana) antibiotic detection. Under the exonuclease III-assisted signal amplification to SC-HCR, we demonstrated the ultrasensitive electrochemical detection of Kana in the linear range from 0.1 pg mL^–1 to 10 ng mL^–1 with a detection limit down to 15.1 fg mL^–1. Meanwhile, a "waste-to-signal" strategy was proposed to achieve the ultrasensitive fluorescence detection of Kana in the linear range from 1 pg mL^–1 to 100 ng mL^–1 with a detection limit of 0.194 pg mL^–1. As the whole assay was performed in homogeneous solutions, this method has simple operability and good repeatability. In addition, the dual-mode cross-validation to detection results decides the excellent accuracy and reliability of the method and its good value for practical application. This SC-HCR also provides a novel approach for efficient assembly of stable DNA nanostructures.