In designing artificial noses modeled after biological olfaction, the challenge has been to generate a similarly large sensor repertoire with the requisite combinatorial complexity to detect odors in the real world.
A further requirement is that the sensors can be manufactured with exact chemical precision and reproducibility.
In a new study published this week in the open-access journal PLoS Biology, Joel White, Mary AtKisson, John Kauer and colleagues demonstrate a previously unreported property of deoxyribonucleic acid. The researchers show that single-stranded DNA molecules tagged with a fluorescent reporter and dried onto solid surfaces can respond to vapor phase odor pulses in a sequence-selective manner.
In the context of detecting chemicals in either the aqueous or vapor phase, two general biological approaches have emerged. The first relies on individual, highly specific single receptors (sensors), each tuned to detect a single molecular species. Some examples include the receptors that mediate pheromone detection in insects, or those that function in neurotransmission.
The second approach, represented by the DNA sensors, is implemented by arrays of receptors with relatively broad responses. Here, specificity emerges from a constellation of receptor types that recognizes the molecule of interest. An example is the olfactory receptors in the main olfactory system of vertebrates.
This study not only highlights DNA's potential for use in a novel and powerful odor detection system, but it also highlights its potential to play other novel roles in vivo, for example as a small molecule receptor, well outside of its familiar one as the repository of information in the genome.