Scientists of the Biophysical Engineering Group of the University of Twente in The Netherlands have developed an ultrasensitive sensor that can be used in a handheld device to, within minutes, detect various viruses and measure their concentration. The sensor could be used to quickly screen people at hospitals, airports and emergency clinics to control outbreaks of diseases such as SARS and the bird flu. All it would take is a tiny sample of saliva, blood, or other body fluid.

In a new virus-detecting sensor, waveguides in a silicon substrate split light into four parallel beams. The beams then form an interference pattern that changes when viruses bind to the antibodies placed on one of the light channels. Researchers at the University of Twente, in the Netherlands, made the device, which can detect low virus concentrations in minutes.
Credit: Credit: Aurel Ymeti

Dr. Aurel Ymeti and others present their results in February’s issue of Nano Letters.

Currently available methods to detect viruses are also sensitive. But they require laborious preparation of the fluid sample and only give results after several days. Since viral diseases can spread rapidly, researchers are looking for easier, faster ways to directly detect viruses. “You want a tool on which you apply the [fluid] sample on-site and in a few minutes say whether or not the person has the SARS virus,” says Aurel Ymeti, a postdoctoral researcher in biophysical engineering and the sensor’s lead developer.

The essential innovation in the technique reported in this paper is the combining of an integrated optics interferometric sensor with antibody-antigen recognition approaches to yield a very sensitive, very rapid test for virus detection. The technology is amenable to miniaturization and mass-production, and thus has significant potential to be developed into a handheld, point-of-care device.

The attention this sensor is currently achieving in the international scientific and nanotechnology community can be understood in the light of recent serious virus outbreaks such as SARS and H5N1 bird flu virus. Future viral outbreaks are a major threat to the societal and economic development throughout the world. Therefore a rapid, sensitive, and easy-to-use test for viral infections is essential to prevent and to control such viral pandemics. Furthermore, a compact, portable device is potentially very useful in remote or developing regions without easy access to sophisticated laboratory facilities.

The technique is better than traditional methods such as PCR (polymerase chain reaction) because of its speed and ease of use without compromising sensitivity. In principle, with a device such as this, minimal pre-processing of samples is required, and one could imagine having several different, interchangeable, detection modules for rapid detection. It’s also possible to consider configuring the device to detect multiple analytes.

So far, the researchers have only tested the sensor for the herpes-simplex virus. On one of the four light-guiding channels, the researchers attach antibodies that bind to the virus. Then they slowly flow a saline solution of the virus along that channel. As the microbes attach to the antibodies, the interference pattern changes. The higher the concentration, the more the interference pattern shifts.

By measuring the change in the pattern for different virus concentrations, the researchers establish a fixed relationship between the two factors. Once this relationship is known, Ymeti says they can estimate the concentration of a new virus solution by analyzing the sensor’s response for a few minutes.

Read more about this story at MIT Technology Review

Souce: The article, entitled, ‘Fast, ultrasensitive virus detection using a young interferometer sensor’ by A. Ymeti, J. Greve, P.V. Lambeck, Th. Wink, S.W.F.M. van Höwell, T.A.M. Beumer, R.R. Wijn, R.G. Heideman, V. Subramaniam, and J.S. Kanger will be published in the February issue of Nano Letters and is already online for subscribers.