DNA biochip may lead to faster genetic screening

A scientist in America has developed a chemical process for building a device that could help doctors predict a patient’s response to drugs or screen patients for thousands of genetic mutations and diseases.

A University of Houston (UH) scientist has developed a chemical process for building a device that could help doctors predict a patient’s response to drugs or screen patients for thousands of genetic mutations and diseases.

The DNA chip – similar to a computer chip but imbedded with DNA molecules instead of electronic circuitry – is designed to probe a biological sample for genetic information that indicates whether the person has a genetic predisposition for certain diseases or conditions.

‘We have put thousands of strands of DNA onto a chip that can screen for the genes linked to breast cancer, cystic fibrosis or prostate cancer, for example,’ said Xiaolian Gao, a professor of biochemistry at the University of Houston. ‘This highly parallel technology allows us to do thousands or tens of thousands of experiments all at once.’

The process Gao and colleagues Xiaochuan Zhou and Erdogan Gulari developed to make the DNA chip involves the use of thousands of commercially available micromirrors to project tiny light patterns onto each postage stamp-sized DNA chip.

Each micromirror can be individually manipulated to reflect light onto an exact location on the DNA chip. Controlled by a computer, the light hits the chip at different spots, where it triggers a chemical reaction. Individual DNA strands are then built up on these locations one by one in a grid-like pattern, and the computer keeps track of information such as where each DNA strand is on the chip.

The strands of DNA fixed on the surface of Gao’s chip act as probes, each strand corresponding to a specific gene or a DNA sequence where a complementary strand in biological samples will bind.

The DNA contained in a blood or a tissue sample can be placed on the chip, and the person’s DNA would then match up with the appropriate probe. A detection device indicates which probes found their mark.

‘If we put specific probes on the chip, we can tell if a person has or doesn’t have these genetic codes present, and we can screen for thousands or tens of thousands of genes at once,’ Gao said. ‘Also, your genetic code may determine whether you have the ability to degrade a certain drug, or how well you will respond to a certain drug.’

Gao and her colleagues have established a company called Xeotron in Houston to manufacture and commercialise their biochip products.