A label-free strategy for direct detection of Staphylococcus aureus in complex matrixes based on RCA and aptamer

Given the significant threat to human health posed by Staphylococcus aureus , rapid and accurate quantification of S. aureus is essential to prevent and diagnose foodborne diseases and to ensure the safety of food consumption. Here, we developed a novel, simple，and label-free biosensor for quantitatively detecting S . aureus by integrating an allosteric aptamer probe and a rolling circle amplification technique. Pathogen S . aureus-specific binding could induce the structural change of the allosteric aptamer beacon to expose the primer for the padlock probe. Then, the primer could trigger the RCA reaction to produce a long-chain singles-tranded DNA harboring repeating Thioflavin T (ThT) aptamer, leading to powerful fluorescence signals. The assay demonstrates sensitivity, specificity, and accuracy, showing its potential as an alternative tool for pathogen detection in different fields, such as food safety monitoring.