Optical Trap Holds Viruses

A Spain-Canada research collaboration has developed a new method to gently trap, manipulate and study tiny, active objects as minuscule as viruses without inflicting any damage.

The partnership between Institute of Photonic Sciences (ICFO) group leader Dr. Romain Quidant and University of Victoria (UVic) engineering professor Dr. Reuven Gordon uses a new approach to establish optical trapping technology.

The team demonstrated that it is possible to use the force of light to hold and manipulate 50-nm particles – 2000 times smaller than the width of a human hair – something previously considered impossible. Since most viruses range from 10 to 300 nm in size, scientists hope that this new method of optical trapping will significantly expand viral research.

Artist’s illustration of a virus optically trapped by a nanohole in a metal film. (Image: ICFO)

“The usual approach to optical trapping does not work well at the nanometer scale,” said Gordon, who spent several months at the Barcelona-based ICFO working on this project. “If the particle is made twice as small, a 30 times more powerful laser is required to hold it, meaning that damaging powers are needed for small particles – especially if they are biological particles such as viruses. We have discovered a much gentler way to hold virus-size particles with a 100 times less power.”

The team, including UVic PhD students Yuanjie Pang and Fatima Eftekhari, conducted its research by directing the light source through a small hole in a metal film that is only a few times as large as the tiny particles being studied. When the particle gets close to the hole, it changes the flow of the light dramatically. This reaction has a favorable effect on trapping since it amplifies the light force but requires less light power.

“This means, for the first time, it may be possible to trap and study viruses, which is something we have started experimenting with,” Gordon said. “One interesting possibility would be to trap a virus and then bring it close to a living cell to see how they interact. Hopefully this will help us better understand the virus-cell interaction and help stop infection.”

The research received support from the Natural Sciences and Engineering Research Council of Canada and was reported this month in the online version of Nature Physics.

For more information, visit: www.icfo.es or www.uvic.ca