Simple and rapid preparation of red fluorescence and red color S. aureus derived nanobioparticles for pathogen detection.

　　Hu W, Zhang Y, Yang H, Yu J, Wei H. 

　　J Microbiol Methods. 2015 May 21;115:47-53. doi: 10.1016/j.mimet.2015.04.018.

　　Abstract 

　　In this study, a simple and rapid method was developed to transform protein A producing Staphylococcus aureus cells into red color and red fluorescent nanobioparticles, which were homogeneous, dispersive and relatively stable with a uniform size of 800nm. The method consists of reaction with a monotetrazolium redox dye at 25°C for 15min and heat inactivation at 65°C for 30min. This method provided the first S. aureus nanobioparticles with the dual property of red color and red fluorescence. Attributed to the IgG binding site known as protein A on their surface, the nanobioparticles could be used as vectors for immunoassays of many bacteria and viruses. Coagglutination test of Escherichia coli O157:H7 observed by naked eyes showed that the detection limitation of the nanobioprobes was 1？106CFU/ml, which was about 100 times more sensitive than the natural uncolored S. aureus bioprobes. Red fluorescence detection and analysis of the coagglutination product by a microplate reader lowered the detection limit to 2.5？104CFU/ml. 

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