Detection of Staphylococcus aureus using acridine orange-doped silica nanoparticles as a fluorescent labelElectronic supplementary information (ESI) available. See DOI: 10.1039/c5ra05599g

• Main Authors: Jiang, Yan, Xu, Yi, Wang, Renjie, Zhao, Bin, Zhang, XiaoDan, Zhao, Huazhou
• Format: Article
• Language: English
• ISSN: 2046-2069
• DOI: 10.1039/c5ra05599g

In this paper, a new type of core-shell fluorescent silica nanoparticles (NPs) carrying amino groups on the surface was designed and prepared by an inverse-microemulsion method using acridine orange (AO) as the dopant fluorophore. These NPs are monodisperse and possess a uniform diameter of ∼80 nm. The introduction of amino groups on the nanoparticles surfaces was proven by IR spectroscopy. Fluorescence studies indicate that the photostability of the NPs was improved compared to that of AO. A highly sensitive, simple and rapid counting approach for Staphylococcus aureus ( S. aureus ) was established by using the NPs as a fluorescent label. Fluorescence intensity and the total number of S. aureus are linearly correlated within the range of 10 3 to 10 7 cfu mL −1 , and the limit of detection is 500 cfu mL −1 . The recovery rate for a spiked sample ranged from 96.5% to 102.7%, and the RSD was lower than 7% (for n = 7). We presume that this method has a large potential for further applications to rapid analysis of pathogens. A rapid, simple, and efficient fluorescence measurement method for S. aureus detection was developed by using a novel AO@SiO 2 -NH 2 fluorescent nanoparticles.