Gold nanoparticle probes for the detection of Salmonella spp. in biological samples

Salmonella is an important pathogen to the food industry and has been frequently identified as the etiological agent of foodborne outbreaks [1]. Salmonella is responsible for more than 1 million outbreaks, resulting in 500+ deaths every year in the United States, and is the leading causative agent among nine foodborne bacterial pathogens resulting in 39% of 15,600 laboratory-diagnosed infections in 2003. A majority of cases of humansalmonellosis are due to the consumption of contaminated egg, poultry, pork, beef, and milk products. Conventional culture methods used for the detection of Salmonella include non-selective preenrichment, followed by enrichment and plating on selective and differential agars. Suspect colonies are confirmed biochemically and serologically, possibly taking up to 7 days to complete the entire procedure [2]. More recently, a number of rapid methods for detection of Salmonella in foods have been developed. Goldnanoparticles have been used in biotechnology over the last 4 decades as immunocytochemical probes as well as biological tags [3]. During the last decade, however, there has been an increasing interest in using nanoparticles in DNA detection [4]. Recent advances in functionalizing particles with oligonucleotides and tailoring their surface properties have paved the way for the development of a series of new and practical biodetection systems [5].This paper reports a new ultra-sensitive nanosensor based on color shift, where selective recognition isaccomplished using gold nanoparticles functionalized with ssDNA probes that recognize and bind to target complementary DNA of Salmonella inv A gene