Scattering gold nanoparticles: strategies for ultra sensitive DNA detection

Dark field (DF) optical detection of gold nanoparticles (GNPs) is a single-molecule\ud method which can be used for sensitive and specific detection of nucleic acid\ud strands such as DNA and RNA. This thesis describes the development of a novel\ud biosensor based on scattering GNPs, from a theoretical idea on paper to a working\ud sensor system which is sensitive for specific DNA detection in the femtomolar range.\ud Furthermore, the modification chemistry and theoretical simulations are described\ud to provide insight into the reported sensing method and experimental setup.\ud The light scattering and absorption properties of GNPs can be utilised for the\ud detection of DNA. Binding of molecules to the GNP influences the local refractive\ud index. The increase in refractive index can be measured as a proportional red-shift\ud of the GNP extinction maximum; therefore GNPs are suitable for use as nanoparticle\ud chemical sensors. Utilizing this approach it is possible to detect DNA in naturally\ud occurring quantities. In total, five different DNA detection assays were investigated