Fast and selective whole cell detection of Staphylococcus aureus bacteria in food samples by paper based colorimetric nanobiosensor using peroxidase-like catalytic activity of DNA-Au/Pt bimetallic nanoclusters

Rapid, easy and highly sensitive detection of S. aureus is very important for human health and food safety. In this study, ultra-small nanoclusters (NC) were prepared using DNA as a template in a one-pot chemical process and set as a bio-receptor conjugation for the detection of whole cell bacteria. Changes in the catalytic activity of this colorimetric probe was seen in the presence of S. aureus bacteria. A paper-based portable device was fabricated for the purpose of detecting bacterial cells. The linear dynamic range of the colorimetric Au/Pt NC based optical sensor covered a large variation of S. aureus concentrations from 108 – 102 CFU/mL and a detection limit of 80 CFU/mL was obtained. Moreover, this microfluidic paper was able to detect whole cells of bacteria very fast in five minutes, with high sensitivity in real samples and revealed to have remarkable potential applications.