Microscopes make new resolution for living cells

By seeing exactly how viruses and other pathogens hijack cells, it may be possible to exploit weak links in their lifecycles and develop targeted treatments.

The method uses microspheres in the sample preparation to resolve to around 50 nanometres — surpassing what was assumed to be a theoretical limit of 200nm, which corresponds to the smallest wavelength of visible light.

The micro-particles form a layer acting like a second lens — exploiting the unusual behaviour of light at boundaries and a phenomenon called internally reflecting evanescent waves.

While not quite achieving the resolving power of electron microscopy, the technique has some distinct advantages in practice, as Prof Lin of Manchester University’s School of Mechanical, Aerospace and Civil Engineering explained.

‘With electron microscopy the cells have to be killed before they can be observed and you can only see the surface. Preparation is very difficult, you have to dehydrate and treat them and it requires a vacuum chamber, which is very expensive. A standard electron microscope costs around half a million pounds whereas a standard optical microscope is around £20,000,’ he said.