At the American Chemical Society’s 243rd National Meeting & Exposition, a research team led by Paresh C. Ray from the Jackson State University in Mississippi has delivered a presentation on a gold nanoparticle-based method to rapidly detect the presence of Salmonella bacteria, particularly the multiple-drug resistant (MDR) strains in lettuce.
Ray explained that the test can be done with a microscopic specimen of lettuce leaf. Salmonella’s presence can be confirmed when the color of the sample changes from pink to blue. The technique is ideal for farm fields and remote regions of the growing nations, and can prevent the supply of contaminated foods by offering on-site pathogen detection.
To rapidly detect the bacteria, the research team has used popcorn-shaped gold nanoparticles that are bonded with antibodies, which are analogous to the molecules that assist the immune system to detect and destroy Salmonella infections. When the antibodies come cross Salmonella bacteria, these molecules carrying the popcorn-shaped gold nanoparticles attach to the bacteria’s outer surface. Since Salmonella bacterium is larger than the nanoparticle-antibody package, multiple packages get attached with every bacterium. The color changing to blue indicates the formation of gold nanoparticle-antibody-Salmonella aggregates.
Ray informed that the method can also be used to destroy the MDR Salmonella by passing light of a specific wavelength into the contaminated water. The light is absorbed by the gold nanoparticles, causing the particles to heat up and burn away the Salmonella bacteria’s outer membrane and destroys the bacteria.
The research team originally synthesized the popcorn-shaped nanoparticles to detect and treat cancer. This popcorn shape has the ability to augment the signal for detection utilizing Raman spectroscopy, which observes the light emitted after the absorption of energy by molecules or atoms. The team has also tested the nanoparticles to find other microorganisms such as E. coli. Ray commented that the patent-pending method can be commercialized. The team is studying the toxicity of gold nanoparticles. Until now, the researchers have not detected any short-term toxicity and will explore possible long-term toxicity.
Source: http://www.acs.org/