Rapid 16S rDNA electrochemical sensor for detection of bacteria based on the integration of target-triggered hairpin self-assembly and tripedal DNA walker amplification

Diseases caused by bacteria pose great challenges to human health. The key to reduce disease transmission and mortality is to develop accurate and rapid methods for the detection and identification of bacteria. Herein, a rapid bacteria 16S rDNA electrochemical sensor based on target-triggered hairpin self-assembly and tripedal DNA walker (TD walker) amplification strategy was constructed. Specific variable region of 16S rDNA fragment of bacteria was used as biomarker. The target-triggered hairpin self-assembly strategy was used to prepare a TD walker. The hairpin DNA probes labeled with ferrocene (Fc) were designed and modified on surface of electrode. The legs of TD walker hybridized with three hairpin probes and opened their hairpin structures. Exo III enzyme recognised hybrid duplexes and selectively digest hairpin probes. The legs of TD walker was released and hybridized with the other three hairpin probes. In this way, the enzyme drived the walkers to walk along electrode interface, until hairpin DNA probes were all removed from the electrode, the Fc was far away from electrode interface. A significantly current reduction signal was obtained and bacteria were detected by recording this response. This strategy was low-cost and scalable, it could continuously recycle low-concentration targets, thus enhanced the detection sensitivity. As the proof-of-concept work, the electrochemical sensor was utilized as detector. The limit of detection (LOD) of detecting Staphylococcus aureus (S. aureus) was 20 CFU mL(-1) and detection time was less than 3 h. It was expected to be widely used in clinical early diagnosis. (C) 2021 Elsevier B.V. All rights reserved.

Automated summary

Diseases caused by bacteria present significant challenges to human health. This study developed a rapid bacteria 16S rDNA electrochemical sensor using a target-triggered hairpin self-assembly and tripedal DNA walker amplification strategy. The sensor showed low-cost, scalable, and enhanced detection sensitivity by continuously recycling low-concentration targets. The sensor had a limit of detection of 20 CFU mL(-1) for detecting Staphylococcus aureus (S. aureus) and a detection time of less than 3 hours, making it potentially useful for clinical early diagnosis.