Combinatorial diversity is the central feature of DNA. In a new study, Joel White, John Kauer, and colleagues
show that a fluorescent dye, linked to a variety of short DNA molecules and dried onto a solid surface, will respond differently to
different odor molecules, depending on the exact DNA sequence to which it is attached. The authors initially used double-stranded DNA, which was linked to a dye that inserts itself between successive rungs on the DNA ladder and dried onto a solid
plastic surface. Therefore, they tested single-stranded DNA oligomers, 20 to 24 bases long, which was linked to a different dye and again dried onto plastic. This study not only highlights DNA''s potential as the scaffolding for a novel and powerful odor detection system, but it also highlights its potential to play other novel roles, well outside of its familiar one as the basis of life. DNA''s combinatorial nature and the finding that solid-state DNA responds to vaporized odors reveals a novel function for this intensely studied molecule: its capacity to produce a vast repertoire of odor sensors for an artificial nose system that can detect many different compounds.