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Last Updated: Tuesday, 5 September 2006, 22:36 GMT 23:36 UK
Nanodoodling shows pipette power
By Elli Leadbeater

Cambridge crest (Ang Int)
The crest is about 60 millionths of a metre across
It is highly accurate, but there is something unusual about this image of the Cambridge University coat of arms.

The picture is about the width of a human hair, and is made up entirely of gently fluorescing DNA.

It is produced by a technique that lets scientists examine the body's tiniest machinery while it is still working.

The ground-breaking approach could provide a fly-on-the-wall view of minute human cells at work, said David Klenerman of Cambridge University.

"We know a lot about the individual molecules that make up living cells, but we need to know how these assemble together," he told the British Association Science Festival.

Previous high-resolution images of cellular machinery have always involved killing the cells, so that scientists could not see them at work.

It opens up the possibility of watching biology at the nanoscale
David Klenerman
The new Cambridge method, called Scanning Ion Conductance Microscopy, is described by Dr Klenerman as a major breakthrough.

"It's like an electron micrograph with live cells," he said. "It opens up the possibility of watching biology at the nanoscale."

Researchers could now examine the tiny proteins on a cell's surface in detail, or watch a virus force its way inside, he explained.

Attention to detail

The technology is based on a tiny hollow tube, called a micropipette, which delivers a small voltage to the surface of the cell.

Protein structures (Ang Int)
The tool images protein structures on the surface of a cell
The closer that the micropipette is to the surface being scanned, the smaller the current which runs between the pipette and another nearby electrode.

The researchers can use the changes in the current to create an image of the surface.

This type of microscopy is not new, but the scientists have now produced a micropipette smaller than any of its predecessors. Resolutions of 10 nanometres (billionths of a metre) can now be achieved.

The instrument can also be used to study tiny cellular gateways, called ion channels, and to push and pull the cell wall to see how it responds.

The Cambridge crest is just a bit of fun, but it demonstrates the power of the new technique: the ability to drop molecules in very specific places at will.

"We have very highly controlled delivery of molecules to the cell's surface, so we've painted pretty pictures using fluorescent DNA. The size of each feature is of the order of a [millionth of a metre]," said David Klenerman.

The researchers hope that the technique could be used to study neuronal disease and heart conditions.

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