Shana Kelley tells Journal of Materials Chemistry about her hot paper.

Can you briefly describe what you achieved in this article?
In this study, we investigated whether biomolecular ligands could be used to synthesize an important class of biological probes: semiconductor quantum dots. We used the building blocks of DNA, mononucleotides, to control the synthesis reaction, and found that the properties of the products obtained were very sensitive to the presence or absence of single functionalties. The results indicate that coded DNA sequences could be used to 'program' the properties of quantum dots.

Could you explain the significance of your article to the non-specialist? 
Nanoscale materials have many uses in biology, medicine, and engineering. The materials we worked with here, semiconductor quantum dots, are particularly useful for biological imaging.  Quantum dots can find specific cells - for example, cancerous cells - in living organisms and then provide a means to visualize these cells because they emit light.  In the work described in this article, we developed a new means to synthesize quantum dots. We used biological molecules in this synthesis, and hope that this route will lead to dots with better biocompatibility.

What has motivated you to conduct this work?
Nucleic acids use sequence information - chemical information - to produce changes in biological function.  I find it intriguing to consider whether the same type of coding could be put to use to program the properties of materials.  The type of proof-of-principle study reported here is a step in that direction.

Where do you see this work developing in the future?
In the future, I think we will have mapped out relationships linking quantum dot properties and DNA sequences, such that discrete sequences can be used to produce defined materials. Folded DNA molecules can also facilitate molecular recognition of other biomolecules, e.g. proteins, and so one could even imagine combining a ligand system and recognition element in one molecule.

Are there any particular challenges facing future research in this area?
For quantum dots to be used as biological labels, keeping the size of the dots small is critical. Otherwise, the labels perturb biological systems too much to be useful. In addition, attaining high quantum yields is difficult in aqueous solution, which is where DNA molecules are useful ligands. Getting maximal luminescence and keeping the diameters of DNA-passivated quantum dots small will be the two challenges we'll have to concentrate on most.

Shana Kelley is a professor of Biochemistry and Pharmacy at the University of Toronto. She holds a Ph.D. from California Institute of Technology, and was an NIH Postdoctoral Fellow at Scripps Research Institute. A major component of her interdisciplinary research efforts are directed towards developing new nanoscale sensors for disease diagnosis. Kelley has received a Research Corporation Innovation Award, a Dreyfus New Faculty Award, a National Science Foundation CAREER Award, an Alfred P. Sloan Fellowship, a Camille Dreyfus Teacher-Scholar Award, the Pittsburgh Conference Achievement Award, and was named to MIT Technology Review's list of Top 100 innovators. Shana Kelley was a cofounder of GeneOhm Sciences, a company devoted to developing new clinical diagnostics.