Letter abstract
Nature Nanotechnology 4, 121 - 125 (2008)
Published online: 21 December 2008 | doi:10.1038/nnano.2008.373
Subject Categories: Nanobiotechnology | Organic-inorganic nanostructures | Photonic structures and devices | Synthesis and processing
One-step DNA-programmed growth of luminescent and biofunctionalized nanocrystals
Nan Ma1, Edward H. Sargent2 & Shana O. Kelley1,3
Abstract
Colloidal semiconductor nanocrystals are widely used as lumiphores in biological imaging because their luminescence is both strong and stable, and because they can be biofunctionalized. During synthesis, nanocrystals are typically passivated with hydrophobic organic ligands1, so it is then necessary either to replace these ligands or encapsulate the nanocrystals with hydrophilic moieties to make the lumiphores soluble in water. Finally, biological labels must be added to allow the detection of nucleic acids, proteins and specific cell types2, 3, 4, 5, 6, 7, 8. This multistep process is time- and labour-intensive and thus out of reach of many researchers who want to use luminescent nanocrystals as customized lumiphores. Here, we show that a single designer ligand—a chimeric DNA molecule—can controllably program both the growth and the biofunctionalization of the nanocrystals. One part of the DNA sequence controls the nanocrystal passivation and serves as a ligand, while another part controls the biorecognition. The synthetic protocol reported here is straightforward and produces a homogeneous dispersion of nanocrystal lumiphores functionalized with a single biomolecular receptor. The nanocrystals exhibit strong optical emission in the visible region, minimal toxicity and have hydrodynamic diameters of 
6 nm, which makes them suitable for bioimaging4. We show that the nanocrystals can specifically bind DNA, proteins or cells that have unique surface recognition markers.
- Department of Pharmaceutical Sciences, Leslie Dan Faculty of Pharmacy, University of Toronto, Toronto, Ontario M5S 3M2, Canada
- Department of Electrical and Computer Engineering, Faculty of Engineering, University of Toronto, Toronto, Ontario M5S 3M2, Canada
- Department of Biochemistry, Faculty of Medicine, University of Toronto, Toronto, Ontario M5S 3M2, Canada
Correspondence to: Shana O. Kelley1,3 e-mail: shana.kelley@utoronto.ca
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