Aptamer-immobilized Gold Nanoparticles Enable Facile and On-site Detection of Staphylococcus aureus

Staphylococcus aureus causes numerous illnesses and national loss in many countries. Therefore, to prevent food poisoning outbreaks, a rapid and straightforward on-site detection method is required without special skills or equipment. Here, we used aptamer-immobilized gold nanoparticles (aiGNPs) for the on-site colorimetric S. aureus detection. For the rapid and facile detection of S. aureus , the SA61 aptamer hybridized with thiol-modified adaptors conjugated onto the GNP surface of approximately 13 nm diameter. The synthesis of GNPs was confirmed using a transmission electron microscopy and energy dispersive spectroscopy. Images using a scanning electron microscope showed attachment of aiGNPs to S. aureus . After 30-min incubation and 20-min centrifugation, the red pellet was specifically observed with the sensitivity of OD 600 0.050 equivalent to 7.5 × 10 6 cells/mL. Besides, aiGNPs could accurately detect S. aureus with a detection limit of OD 600 0.10 equivalent to 1.5 × 10 7 cells/mL even in the mixed sample with Escherichia coli . Quantitative analysis was performed between relative area and cell concentration. Because this method enables fast and specific S. aureus detection without special skills or expensive equipment, aiGNPs could enable a rapid and effective on-site detection of S. aureus to prevent pathogenic outbreaks.