Fluorescent nanoparticles for multiplexed bacteria monitoring.

Rapid, sensitive, and selective detection of pathogenic bacteria is extremely important for proper containment, diagnosis, and treatment of diseases like foodborne illness, sepsis, and bioterrorism. Most current bacterial detection methods are time-consuming and laborious and can detect only one bacterial pathogen at a time. We have developed a method for sensitive, multiplexed monitoring of bacterial pathogens within 30 min using multicolored FRET (fluorescence resonance energy transfer) silica NPs (nanoparticles). By varying the ratio of three tandem dyes coencapsulated into the NPs, we have synthesized NPs that emit unique colors upon excitation with a single wavelength. When these NPs were conjugated to monoclonal antibodies specific for the pathogenic bacteria species Escherichia coli, Salmonella typhimurium, and Staphylococcus aureus, and then incubated with small concentrations of the bacteria, simultaneous and sensitive detection of the multiple bacterial targets was achieved.