Ultrasensitive bacterial detection using colorimetric detector of DNA nanosheets with enzyme activity

Staphylococcus aureus is a common foodborne pathogen that poses a serious threat to public health, necessitating the development of simple, ultrasensitive, and highly selective detection methods. In this study, we designed a colorimetric sensor by incorporating SA 31 aptamers with DNA nanosheet-templated copper nanoclusters (DNS/CuNCs) for the precise detection of S. aureus. The DNS/CuNCs exhibit peroxidase-like activity, catalyzing the oxidation of TMB to ox-TMB, resulting in a color change directly correlated with the bacterial concentration. This bioassay demonstrated a broad detection range of 10-10⁷ CFU/mL and an impressive detection limit of 3 CFU/mL, surpassing most previous reports. In addition, DNS/CuNCs-SA 31 biosensor effectively detected S. aureus at low concentration as low as 58 CFU/mL in practical samples including drinking water, orange juice, and milk using a smartphone-based readout. The study introduces a novel approach for the sensitive and selective detection of S. aureus leveraging the enzyme-like activity of DNA nanostructures, offering a convenient and efficient solution of real-world pathogen monitoring.