'Limitless' microscope to aid virus research

An optical microscope that uses light and is so powerful that it can capture living viruses and be used to view the working biological machinery that keeps human cells alive has been invented by British scientists.

The microscope exploits a new method of manipulating light so that there is, theoretically, no limit on the size of a living feature that can be seen by the human eye, the Manchester University researchers said.

Unlike the most powerful electron microscopes – which can see down to the scale of individual molecules – or fluorescent-based microscopes – which rely on the use of coloured dyes – the new light microscope does not need to interfere in any way with the living material it is used to study.

"Seeing inside a cell directly without [using dyes] and seeing living viruses directly could revolutionise the way cells are studied and allow us to examine closely viruses and biomedicine for the first time," Professor Lin Li, of Manchester University, said.

"This is a world record in terms of how small an optical microscope can go by direct imaging under a light source covering the whole range of optical spectrum."

The device overcomes a physical limitation on the use of light for microscopy and, in doing so, can capture details that are 20 times smaller than the tiniest objects seen by conventional light microscopes, which are limited by the physical wave length of light in the optical spectrum. Previously, optical microscopes could see down to a minimum scale of one micrometre, or 0.001 millimetres. But by combining optical microscopy with a transparent "microsphere" for extra magnification, the scientists were able to see down to a scale of just 50 nanometres, which is 20 times smaller than the previous limit of optical microscopy.

"We believe that is just the start and we will be able to see far smaller items," Professor Li said.

"Theoretically, there is no limit on how small an object we will be able to see."