A protein patterning technique could help fight cancer, say US scientists.

Yitshak Zohar and colleagues from the University of Arizona have developed a new way of creating patterns of proteins on surfaces. Their method can create very detailed patterns without damaging the proteins. They successfully constructed a chessboard pattern of two different antibody proteins, with neatly aligned squares only 125 micrometres across.

Zohar's scheme uses a layer of agarose, a type of gel commonly used in biological analysis, to defend the protein layers from harm caused by the photoresist. After the pattern is created, an enzyme is used to selectively eat away the protective agarose layer, revealing the intact protein layers underneath.

There are two conventional ways of making small-scale patterns on surfaces. Hard lithography involves coating parts of the pattern in a protective layer (known as a photoresist) and using chemicals, usually acids, to etch away the unprotected parts. Soft lithography uses a stamp to print the pattern, in much the same way as rubber stamps are used to print ink onto paper.

Each of these techniques has shortcomings. Hard lithography can create very detailed patterns, but the chemicals involved often damage proteins. Soft lithography is less damaging but is not as accurate as hard lithography and can't be used to make detailed patterns or to carefully align two types of protein.

Zohar's technique is an important advance as it creates precise patterns without damaging the proteins.

Doug Weibel, a biochemist at the University of Wisconsin-Madison, US, said, 'the patterns of protein described in this paper are unique - they are not easily made using other techniques.' He suggested that the process could be used for tissue engineering.

Eventually the team hopes to use the technique to create microdevices that can remove circulating cancer cells from the bloodstream. Zohar said 'the next challenge is to repeat the process in a microchannel, where the main problem is keeping the process temperature very low to maintain the integrity and functionality of the protein layers.'

Clare Boothby