Construction of linear causal-regulated and autocatalysis-driven DNA circuits for highly sensitive and specific detection of Salmonella Typhimurium

Abstract

The detection of pathogenic bacteria plays a crucial role in ensuring food safety and public health. The integration of isothermal amplification technology with the clustered regularly interspaced short palindromic repeats (CRISPR) and CRISPR-associated proteins (Cas) system offers a versatile approach for detecting foodborne pathogens. However, this method is often constrained by the incompatibility of the reaction systems and the lack of control over CRISPR/Cas activity. Here, we demonstrated a fluorescence biosensing strategy based on linear causal-regulated and autocatalysis-driven DNA circuits (termed LC@ADC) for highly sensitive and specific detection of Salmonella Typhimurium (S. Typhimurium). The approach of combining hybridization chain reaction (HCR) with DNAzyme-driven CRISPR/Cas12a activation was proposed for the first time, enabling not only one-step cascade signal amplification but also controllable DNA circuits. The LC@ADC strategy is capable of quantifying concentrations of S. Typhimurium ranging from 10 to 1 × 10⁵ CFU/mL, with a detection limit as low as 6.53 CFU/mL. Furthermore, the LC@ADC strategy has been successfully employed for the detection of S. Typhimurium in samples of orange juice, chicken, and lake water. Therefore, this strategy provides a novel approach for the high-performance detection of pathogenic bacteria.