Albany 2013: Book of Abstracts
June 11-15 2013
©Adenine Press (2012)
DNA origami as a platform for assembly of nanophotonic elements
Achieving DNA-functionalized semiconductor quantum dots (QDs) that are robust enough to be compatible with the DNA nanotechnology that withstand precipitation at high temperature and ionic strength is a challenge. Here we report a method that facilitates the synthesis of stable core/shell (1 to 20 monolayers) QD-DNA conjugates in which the end part (5-10 nucleotides) of the phosphorothiolated oligonucleotides is embedded within the shell of the QD. These reliable QD–DNA conjugates exhibit excellent chemical, colloidal and photonic stability over a wide pH range (4-12) and at high salt concentrations (>100 mM Na+ or Mg2+), bright fluorescence emission with quantum yields of up to 70%, and broad spectral tunability with emission ranging from UV to the NIR (360-800 nm). The assembly of these different QDs into DNA origami into well-controlled patterns was demonstrated (Deng et al. 2012).
We also used DNA origami as a platform to co-assemble a gold nanoparticle with 20 nm diameter (AuNP) and an organic fluorophore (TAMRA) and studied the distance dependent plasmonic interactions between the particle and the dye using steady state fluorescence and lifetime measurements. Greater fluorescence quenching was found at smaller inter-particle distances, which was accompanied by an enhancement of the decay rate. We further fabricated 20 nm and 30 nm AuNP homodimers with different inter-particle distances using DNA origami scaffolds and positioned a Cy3 fluorophore between the AuNPs in both assemblies. Up to 50% enhancement of the Cy3 fluorescence quantum efficiency was observed for the dye between the 30 nm AuNPs. These results are in good agreement with the theoretical simulations (Pal et al. 2013).
This research has been supported by NSF and ONR.
2. S. Pal. P. Dutta, H. Wang, Z. Deng, S. ZOu, H. Yan, Y. Liu. Quantum efficiency modification of organic fluorophores using gold nanoparticles on DNA origami scaffold. (2013) J. Phys. Chem. C. In revision.
Department of Chemistry and Biochemistry