January 2002

Bar-Coding Life

Biotech: Tiny tags to decode disease.

By Alexandra Stikeman

Bar codes have revolutionized how everyone from warehouse managers to pharmacists keeps track of items. Mountain View, CA-based SurroMed is using them to help biologists track genes, proteins and other molecules. SurroMed's microscopic bar codes could eventually be used to identify and quantify thousands of different molecules in a sample of a fluid like blood, making biological and medical tests far more informative.

SurroMed's "nanobarcodes" work much like conventional bar codes, except they are microscopic rods, striped with bands of gold, silver and other metals. Varying the width, number and order of the stripes could generate thousands, if not hundreds of thousands, of unique identifiers, says SurroMed CEO Gordon Ringold. The rods could be attached to probes that bind to specific biological molecules, forming bar-coded tags.

The problem with existing fluorescent tags, which are the workhorses in many of today's biological tests, is that they only let researchers analyze a few different types of molecules at a time. With nanobarcodes, though, thousands of different tags could be added to a biological sample at once. A sample-reading device would then snap a microscopic image, and a computer would identify all the tagged molecules in the image by the nanobarcodes attached to them.

"This is like miniature supermarket technology," says Chad Mirkin, director of the Institute for Nanotechnology at Northwestern University. "Conceptually, this is a major advance" in biological analysis, he adds. SurroMed hopes its nanobarcodes will help researchers identify patterns of perhaps hundreds of molecules that form molecular signatures for different diseases, and for different stages of illness and recovery. More complete knowledge of the molecules involved in disease could help researchers develop better drugs and could form the basis for highly specific diagnostic tests.

In preliminary studies, the company is using nanobarcodes to identify molecular signatures in diabetics' blood, Alzheimer's patients' brain fluid and other biological samples. According to chief technical officer Michael Natan, the first commercial nanobarcodes for research could be available in the next couple of years.