Low-cost technique to detect rotavirus

Researchers at the Universidad Politécnica de Madrid (UPM) have found a new, low-cost way to enhance detection capacity of small concentrations of rotavirus - a sphere-shaped virus up to 75 nm in diameter that has the appearance of a wheel, seen from an electron microscope.

Rotavirus is the most common cause of severe diarrhoea in infants and children worldwide, commonly called gastroenteritis. The treatment for gastroenteritis is simply to stay hydrated until the body’s defences overcome the disease, but nearly half a million children die every year due to dehydration caused by diarrhoea and vomiting - mainly in developing countries.

The diagnosis of rotavirus is usually made through an enzyme-linked immunosorbent assay, which must be made by qualified staff in labs and require a supply of host enzymes. Dr Miguel Holgado Bolaños and his team from UPM sought to develop label-free optical biosensors that do not require the presence of enzymes that fix either the substance to be detected or the marker responsible for any detectable physical phenomenon.

The biosensors consist of smooth or micro-nano textured surfaces made with a polymer whose surface has been chemically treated to be similar to a bioreceptor. Once the surface is coated by the bioreceptor, the biosensor is sensitive and selective towards a determined type of biomolecule. When the substance to detect is recognised by a bioreceptor, this substance produces a change in its optical response (transduction). This change is usually the movement of the maximum or minimum position of the interferometric pattern.

The researchers proposed an easy interferometric system based on two Fabry Perot interferometers - one used as a reference, and the other to capture the substance or virus. The system is easy to install in compact devices and can be used by non-expert users. The researchers were able to use it to detect both the presence of the virus and its antibody - the former in its source (eg, water) and the latter in blood plasma.

According to the researchers, the low-cost technique will allow developing countries to reduce the high infant mortality rates caused by the rotavirus.

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