Enhancing the Efficiency of FRET using DNA and Biotin and Streptavidin Proteins to Control Spacing

In an effort to enhance Forster Resonance Energy Transfer between two fluorescent molecules, surface plasmons are generated on nanopatterned gold substrates with the molecules on top. Surface plasmons are known to enhance fluorescence and have previously been proven to enhance FRET in certain circumstances by increasing the local density of optical states. In previous years of this work, DNA with molecules along its backbone has been attached to the surface of these nanopatterned gold substrates to predictably space the fluorescent molecules and ascertain the specifications of FRET enhancement. Attaching the DNA directly to the gold surfaces, however, continually gave results inconsistent with current understanding of FRET enhancement. In an attempt to improve this method, biotin and streptavidin have been added to the process. These two proteins have an extremely strong bond to each other and can be attached to gold and DNA. In this way the DNA used can be shorter and more precisely attached to gold surfaces. Biotin, streptavidin, and DNA all have measured sizes and these sizes, along with knowledge of the bonds and precise spacing of the molecules along the DNA, can be used to adjust variables in the experiment. These variables include distance between the fluorescent molecules and the surface, as well as distance between the donor and acceptor molecules in the FRET process. In this way FRET enhancement can be more thoroughly understood.