By Gary Flood
The computer industry’s insatiable need for ever faster and better ‘brains’ – which has led us from vacuum tubes through transistors to the silicon chip to some disappointments with gallium arsenide and probably soon to ways of working with light – has taken a twist straight out of sci-fi: welcome aboard, Mr Biological Chip. For instead of using layers of materials like silicon or gallium arsenide, which have attractive properties to physicists and hardware engineers owing to their cheapness and superlow conductivity, we now have a type of microprocessor built with yer actual deoxyribonucleic acid (DNA), the very building block of life itself. This at least according to The New York Times, which ran a story last week on the envelope-pushing work being carried out by one of the handful of pioneering biochip companies in the field, a Santa Clara outfit called Affymetrix Inc (not to be confused with Java development tool supplier Asymetrix Corp), a spin-out of pharmaceutical giant Glaxo Plc. Affymetrix has already produced a real product, a chip that tracks mutations in the Human Immuno-deficiency Virus as it develops resistance to drugs; and a second is due which will detect changes in the p53 gene, which tends to undergo changes in many forms of cancer. Academic biologists and chemical companies are also using the things to explore gene expression and gene mutation problems. The company, founded in 1991, has brought together a range of experts from semiconductor design to molecular biology. Apparently the actual devices are squares of glass, about the size of a dime, enclosed in small black cartridges; on the glass is a network of DNA fibers called probes, of which there can be up to 1,000. The genes to be tested are injected in a solution with a fluorescent chemical into the cartridge, a laser scans the patterns, thus revealing the sequence order of the DNA. It’s worth noting that according to the Affymetrix designers, so much gene research is ongoing and available over the Internet that a programmer can download a profile of a gene straight to his workstation to design the masks that are used to build the finished chip, rather than mess about with any test tubes. There are some truly exciting possibilities here in using this technology to track many aspects of human gene behavior, claims the company. The aim is to cram 1.6 million probes into that dime, a point at which we truly move into Star Trek level medical-computer biology.
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