DNA origami has been actively used as a template to organize a variety of materials with molecular precision for the last few years.  Small assemblages of inorganic nanoparticles arranged in this way are of great interest because of potential applications in sensors, drug delivery systems and optical devices. In order to assemble such nanostructures with high yields, it is important to understand the kinetics of the dynamic binding process using real-time monitoring. Here we present in situ study of the kinetics of quantum dot (Qdot) binding to DNA origami in solution using a three-dimensional, real-time tracking system that enables us to observe individual Qdots and DNA origami. We have studied the binding process of Qdots to DNA origami which is engineered with 1, 2 or 3 binding sites. The tracking system enables us to make precise measurements of diffusion coefficient (D) allowing us to distinguish free Qdots, 1Qdot-DNA origami, 2Qdot-DNA origami, and 3Qdot-DNA origami. The fluorescence signals of tracked Qdots and DNA origami are collected by single photon detectors with 4 picosecond resolution, which provides a rich secondary data channel that allows us, in this case, to measure the second-order photon correlation function g2(t), which is used to identify single-photon sources. These measurements provide an additional means of quantifying the number of bound species.  Measurements of individual particles enable us to understand the constituent components of ensemble measurements.

Kinetics of quantum dot-DNA origami binding: A single particle, 3D real-time tracking study

244th National Meeting (2012)

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