Researchers at the University of Arizona have developed a simple and inexpensive method that can be used to detect tiny traces of norovirus in water samples. The technique involves a smartphone camera and a paper microfluidics device, and could help to identify sources of norovirus before it can cause illness.
In the US, norovirus causes approximately 20 million cases of food poisoning annually. However, the virus isn’t just responsible for temporary illness; it can sometimes lead to death, and is estimated to cause 200,000 deaths globally every year.
The virus often blazes through confined areas, such as cruise ships or hospitals, but can also infect water supplies of entire communities, resulting in widespread illness. As few as 10 viral particles can be enough to make someone ill. Consequently, the virus can create health issues at very low concentrations in drinking water.
Detecting such low concentrations is possible, but typically requires a variety of expensive laboratory equipment, meaning that assessing water samples in the field is not usually practical. These researchers at the University of Arizona have devised an inexpensive, portable and convenient alternative.
The technique involves a paper microfluidic chip. “Paper substrate is very cheap and easy to store, and we can fabricate these chips easily,” said Soo Chung, a researcher involved in the study. “The fibrous structure of paper also allows liquid to flow spontaneously without using the pumping systems other chips, such as silicon chips, usually require.”
A user can add a water sample to one end of the paper chip, and small fluorescent polystyrene beads that are studded with antibodies against norovirus to the other. The antibodies bind to any norovirus particles in the sample, causing the beads to clump together.
These clumps can then be visualized using a smartphone attached to a small and inexpensive microscope that has an app that can count the fluorescent clumps to provide an indication of the number of norovirus particles in the sample. “You don’t have to be a scientist or an engineer to run the device,” said Yoon said. “Analysis will be done automatically by the smartphone app, so all you have to worry about is loading a sample of water onto the chip.”
Here’s a video from the American Chemical Socity about the new norovirus detector: