Sensitive detection of Salmonella with fluorescent bioconjugated nanoparticles probe

A sensitive and specific method for detecting foodborne pathogen, with Salmonella as model analyte, has been developed basing upon DNA hybridization and fluorescent bioconjugated nanoparticles probe. The indicator probe was designed through bioconjugating the Salmonella   sequence-specific oligonucleotide with the fluorescent Ru(bpy)32+-doped silica nanoparticles that were prepared by a microemulsion method. Through a sandwich-type DNA hybridization procedure, the target Salmonella DNA was captured and the indicator probe was assembled onto solid matrix so that the Salmonella DNA can be measured by the fluorescent signals of assembled indicator probes. Under optimal conditions, the calibration graph for detection of target Salmonella DNA is linear over the range of 10–10,000 fmol/L with a detection limit of 3 fmol/L. The proposed method was also applied to detect Salmonella in mixed bacteria sample. It gives the detection limit of 30 cfu/mL. The method offers a potential resolution for simple, rapid and sensitive detection of foodborne pathogens in food, clinical and environmental samples.