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World's smallest Smiley made from DNA

A research scientist in the United States has taken the art of "origami" folding to new heights ? using not paper but DNA.

india Updated: Apr 04, 2006 13:31 IST

A nanotechnologist has created the world's smallest and most plentiful Smiley—a tiny face measuring a few billionths of a metre across that is assembled from strands of DNA.

Fifty billion Smileys, each a thousand times smaller than the diameter of a human hair, can be made at a stroke under the technique pioneered by Paul Rothemund at the California Institute of Technology (Caltech).

DNA, the molecule that comprises living things, has long been known for its versatility as a microscopic building block.

The molecule can be "cut" using enzymes and reassembled using matching rungs in its double-helix structure. This theoretically opens the way to making DNA quantum computers and nano-level devices including injectable robots that can monitor the body's tissues for good health.

But, until now, nano-assembly has been a complex atom-by-atom procedure that is also costly, because it is carried out in a vacuum or at extremely coldly temperatures.

Rothemund, writing in Thursday's issue of Nature, describes a far simpler and much cheaper process in which long, single strands of DNA can be folded back and forth to form a basic scaffold.

The basic structure is then supplemented by around 200 shorter strands, which both strengthen it and act rather like pixels in a computer or TV image, thus providing a shape that can bear a complex pattern.

In a potent demonstration of his so-called DNA origami technique, Rothemund has created half a dozen shapes, including a five-pointed star, a snowflake, a picture of the double helix and a map of the Americas in which one nanometre (one billionth of a metre) represents 120 kilometres (70 miles).

Rothemund, whose paper is published on Thursday in the British science weekly Nature, has been working on flat, two-dimensional shapes but says that 3-D structures in DNA should be quite feasible with this technique, Caltech said in a press release.

One application would be a nano-scale "cage" in which pharmaceutical researchers, working on novel drugs, could sequester enzymes until they were ready for use in turning other proteins on and off.

"In this research, Paul has scored a few unusual 'firsts' for humanity," his colleague, Erik Winfree, said.

"In a typical reaction, he can make about 50 billion Smiley faces. I think this is the most concentrated happiness ever created."

Winfree said there could be huge potential benefits from this apparently whimsical work, as it provided a major new tool for putting molecular-level machinery together.

First Published: Mar 16, 2006 14:46 IST