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.