DNA Biochip for Fast Genetic Screening

A new DNA biochip is designed to probe a patient's biologic sample for genetic information that indicates whether the patient has a genetic predisposition for certain diseases or conditions, enabling a doctor to predict the patient's response to drugs or to screen for genetic mutations and diseases.

There are other biochip technologies available or in development, says Xiaolian Gao, a professor at the University of Houston (TX, USA) who developed the biochip. The advantage of the new chip is a flexible, high quality, and more cost- efficient technology that will allow scientists to make custom-designed chips containing not only DNA but also RNA, peptides, or libraries of organic molecules. Gao has collaborated with two researchers from the University of Michigan (Ann Arbor, USA) on the production of the biochip and has established a company called Xeotron in Houston to manufacture the biochip products. DNA chips are now being produced for testing.

The manufacturing process involves the use of thousands of micromirrors to project tiny light patterns less than the diameter of a human hair onto each DNA chip, which is smaller than a postage stamp. 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, while the computer keeps track of where each strand is on the chip.

Each strand corresponds to a specific gene or DNA sequence where a complementary strand in biologic samples will bind. The DNA contained in a blood or tissue sample can be placed on the chip and would then match up with the appropriate probe. A detection device indicates which probes find their mark. "If we put specific probes on the chip, we can tell if an individual has or doesn't have these genetic codes present, and we can screen for thousands or tens of thousands of genes at once,” says Gao.




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