Biomod/2013/North Carolina State University/Design

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Heterodimer Design

Our experiment hinges on the specific properties of our most basic "part" our asymmetrical heterodimer. Composed of a gold nanorod, 80 nanometers long by 20 nanometers wide, and a quantum dot with a radius of seven nanometers, these heterodimers have unique optical and electrical properties due to the close proximity of their components. This is due to the plasmonic resonance between the gold nanorod and the quantum dot. Plasmonic resonance is the term for the induced fluctuations in particle's surrounding electric field. When two particles are near each other these electric fields can interact inducing wave like propagations along the particle's surface. When two particles are close together, on the nanoscale, these propagations interact in a way similar to a two spring system. Should the particles be too close you get an effect known as quenching in which the response (fluorescence under UV for quantum dots) is decreased. Should the particles be within a sweet spot you achieve an effect known as enhancement in which the response is increased. This is similar to two springs operating at the same resonant frequency. For our experiment we desire an enhancement interaction between the gold nanorods and quantum dots. Previous papers have demonstrated that a gap of approximately 30 nanometers allows for enhancement of the quantum dot fluorescence. Therefore our DNA origami is designed to separate the gold rod and quantum dot by 30 nanometers. Below is a cadnano representation of our DNA origami used to achieved this effect.


Our DNA origami begins as a flat sheet to which our gold nanorod (functionalized with conjugate single strand DNA) and quantum dot bind at specific locations. This is incredibly important due to the very finicky nature of plasmonic resonance.

binding cartoon

Once the particles have attached we add the final staple strands that roll the origami into a tube like shape. This is the final step to create our heterodimers. Next we will suspend them in PEO and electrospin the solution to produce our ordered array.


The left side of the origami is trailing double strand DNA to aid in the orientation of the heterodimers in the polymer fibers. These strands act as kitetails producing drag in the viscous polymer to ensure that the heterodimer orients head to tail with the others. This way a uniform array will be produced.


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