Research Highlights

doi:10.1038/nindia.2015.94 Published online 16 July 2015

Glowing strip detects pathogen in milk

Researchers have developed a fluorescent strip that can detect traces of the disease-causing bacterium Brucella abortus in milk samples, making it potentially useful for monitoring milk samples1.

The bacterium causes brucellosis, an infectious disease that is transmitted to humans via the consumption of unpasteurized milk products and direct contact with infected animals. Existing techniques for detecting the bacterium in milk samples are complex and tedious.

To devise a rapid detection technique, the researchers attached a fluorescent dye to synthesized silica nanoparticles coated with lipopolysaccharides isolated from the outer membrane of the bacterium. These lipopolysaccharides acted as bacterial antigens and bound to antibodies generated against the bacterial antigens in contaminated milk samples.

The scientists transferred the antigen-coated nanoparticles to a strip based on a nitrocellulose membrane that was deposited on a polyester film coated with an adhesive. Besides detecting bacteria-containing milk samples, the strip also had a separate section that glowed when exposed to bacteria-free milk samples.

When the researchers added a few microlitres of contaminated milk samples to the strip under ultraviolet light, two apple-green fluorescent spots appeared. In contrast, when bacteria-free milk samples were added, only one apple-green spot appeared on the strip. The test could be performed in 15 minutes.

The researchers add that this strip could be used to rapidly detect other disease biomarkers in animals, alleviating the need to invasively draw blood.


References

1. Vyas, S. S. et al. Development of immunochromatographic strip test using fluorescent, micellar silica nanosensors for rapid detection of B. abortus antibodies in milk samples. Biosens. Bioelectron. 70, 254–260 (2015)