A new device detects small amounts of norovirus in water. Source: American Chemical SocietyResearchers from the University of Arizona have devised a method to detect low-level concentrations of norovirus, which causes food poisoning.

Because just 18 virions of norovirus can result in illnesses, a team of researchers developed a simple, inexpensive and portable method for detecting norovirus in low levels using a smartphone and paper microfluidic chips.

Researchers added potentially contaminated water to one end of a paper microfluidic chip. At the other end of the chip, tiny fluorescent polystyrene beads were added, each of which is attached to a norovirus antibody. In the presence of norovirus, the antibodies will attach to each virus particle, creating a clump of fluorescent beads.

Those clumps are detectable and photographable using a smartphone microscope. Likewise, an accompanying smartphone app enables the researchers to count the illuminated pixels in the image to identify the number of beads and, ultimately, the number of norovirus particles present in the sample.

"Norovirus particles are too small to be imaged by a smartphone microscope, and so are antibodies," said Jeong-Yeol Yoon, a researcher in the department of biomedical engineering. "But when you have two or three or more of these beads joined together, that indicates that the norovirus is there, causing the beads to aggregate."

Taking expensive diagnostics out of the lab, the team devised a low-cost, water quality device to detect norovirus in the field, for instance in settings like cruise ships where outbreaks of the norovirus have a high rate of incidence. Eventually, the team intends to create a method for early detection of norovirus infections in patients and to possibly detect other hazards, like the presence of potential cancer-causing chemicals.

The team published their findings in ACS Omega, the journal of the American Chemical Society, and Yoon will present the research at the ACS Fall 2019 National Meeting & Exposition in San Diego held Aug. 25 through Aug. 29.