Quantum Dot Fluorescence Lifetime Engineering with DNA Origami Constructs
James A. Liddle, Seung-Hyeon Ko, Kan Du
The ability to organize nanostructures of disparate types and materials such as metal nanoparticles and semiconductor quantum dots is challenging but essential for the creation of novel materials and devices. Metal nanoparticles (NPs) have interesting individual plasmonic properties and can be organized to exhibit useful collective responses. Quantum dots (Qdots) provide a powerful means to optically access the nanoscale. Bringing the two together in a well-controlled manner can create structures with interesting properties such as fluorescence enhancement/quenching and high efficiency Förster resonance energy transfer. It also has been an area of intense study, both theoretical and experimental, for a wide range of applications including photodetectors, optical modulators and nanoscale lasers. In particular, changing the fluorescence intensity and lifetime of Qdots, when proximate to metal NPs can be used in sensing applications because of the strong distance-dependence of interaction between them and the ability to engineer the properties (e.g. size, absorbance/emission spectrum) of the individual components over wide ranges. In this work, we exploit DNA origami to develop a flexible approach to fluorescence lifetime engineering of CdSe/ZnS (core/shell) Qdots by controlling their coupling to adjacent gold nanoparticles (AuNPs) at geometrically different locations on the DNA origami.