DNA-functionalized plasmonic nanostructures for biosensing and living cell imaging
Date of Issue2015-12-10
School of Chemical and Biomedical Engineering
Research in this thesis focused on developing core-shell DNA-functionalized plasmonic nanostructures which exhibit integrated properties of the "hard" nanoparticle core and "soft" DNA shell. The grafted DNA strands that exhibit stimuli-responsive and/or hybridization-induced structural changes and specific recognition of protein targets provide a myriad of mechanisms to tailor the self-assembly of the plasmonic nanostructures and thus the interparticle plasmonic coupling. The distinctly different plasmonic properties of the assemblies and individual blocks offers the possibilities of developing sensors for the mechanisms inherent to the DNA strands. In addition, our work led to a new approach to preparing DNA-nanoparticle conjugates based on polydopamine coating to address the problems associated with the traditional method based on the labile metal-sulphur bond. We have demonstrated that it is possible to confine self-assembly of DNA-nanoparticle conjugates at certain stages to form discrete assemblies instead of macroscopic aggregates. A particular type of assemblies of plasmonic nanostructures we focused on is the “core-satellite” structures with a number of smaller nanoparticles surrounding the larger nanoparticles. Our results showed that the core-satellite assembly with defined sizes made it possible to sense particular substances inside living cells and at single-particle level, which are not available for macroscopic assemblies.