Gold nanoparticles diagnose flu in minutes

Ashley N. Paddock, ashley.paddock@photonics.com

Physicians and public health officials may no longer have to choose between flu tests that are accurate yet time-consuming or rapid but error-prone, thanks to a new detection method that can identify influenza in minutes at only a fraction of a penny per exam.

A new test from the University of Georgia now offers the best of both worlds. By coating gold nanoparticles with antibodies that bind to specific strains of the flu virus and measuring how the particles scatter laser light, the technology can detect influenza at the point of patient care.

“We routinely survey the influenza landscape and work toward an improved understanding of influenza infection, replication and disease pathogenesis so we can develop enhanced disease intervention strategies,” said Ralph Tripp, Georgia Research Alliance Eminent Scholar in Vaccine Development at the university’s College of Veterinary Medicine and associate director of the Influenza Pathogenesis and Immunology Research Center. “The recent pandemic H1N1 outbreak highlighted the need for rapid, specific and sensitive detection of influenza.”

Ralph Tripp and colleagues at the University of Georgia College of Veterinary Medicine have developed a quick and inexpensive flu test that can be given on the spot. Courtesy of UGA Photography Service.

Working in the university’s Nanoscale Science and Engineering Center, Tripp and colleague Jeremy Driskell linked antibodies with gold nanoparticles – the complex then will aggregate with any virus present in a sample. Although gold nanoparticles are very efficient at scattering light, the researchers found that biological molecules such as viruses are intrinsically weak light scatterers. The clustering of the virus with gold nanoparticles causes the scattered light to fluctuate in a predictable and measurable pattern.

Gold is a costly metal, but the new diagnostic test uses such a small amount, it would cost only one-hundredth of a cent per test.

The implications of the new test are wide-ranging. Although it works for influenza, Tripp said it could be altered to detect any number of infectious agents by exchanging the anti-influenza antibody with an antibody for another pathogen.

“We have developed an assay that allows for rapid and specific detection of influenza in a format similar to a pregnancy test – that is, detection can be done by a lay person detecting a color change indicative of a positive result,” Tripp said. “We anticipate this will, at minimum, complement existing antibody-based assays, but more likely advance surveillance and advance our ability to detect specific influenza virus infection, allowing for more personal-care medicine.”

The researchers’ findings appeared online June 13 in Analyst (doi: 10.1039/C1AN15303J).