optical nanoantennas for photocatalysis and single molecule spectroscopic applications

Abstract

The present thesis delves into exploring the diverse uses of optical nanoantennas, newlineincluding single molecule sensing, fluorescence enhancement, photocatalysis, newlineelectrocatalysis, and lot more. Plasmonic nanostructures form the building blocks of newlineoptical nanoantennas. newlineThey are excellent choices because of their distinctive newlineplasmonic properties, specifically referred to as localized surface plasmon resonance newline(LSPR). The tuning of LSPR for plasmonic nanostructures is achievable by modifying newlinethe size, morphology, composition, interparticle spacing, and dielectric of the medium newlineand metal itself. The localized surface plasmons decay radiatively causing newlineelectromagnetic field enhancement and non-radiatively by hot electrons and holes, newlineand plasmonic heat. The combination of electron-hole pairs, strong electric fields, and newlineheat generation during LSP excitation and decay processes enables the various newlineapplications mentioned earlier. Anisotropic plasmonic nanostructures significantly newlineboost the signals of Raman and fluorescence. Gold, renowned for its stability, is a newlinesuperior plasmonic material commonly employed in nanoplasmonics due to its newlineexceptional properties. On the other hand, when different varieties of plasmonic metal newlinenanostructures are merged such as core-shell nanostructures, they possess the ability newlineto generate exceptional plasmonic functionalities, rendering them appealing for newlinevarious applications. newlineBuilding upon the context outlined previously, the third chapter of the thesis involves newlinea structured method for designing a custom arrangement of Gold nanobipyramids (Au newlineNBPs) monomer and dimer nanoantenna engineered precisely based on DNA origami newlinetechnique. Utilizing these precisely arranged nanostructures, Surface-Enhanced newlineRaman Spectroscopy based detection of Thioflavin T (ThT), a well-established newlinemarker for the detection of amyloid fibrils formation was carried out where G- newlineQuadruplexes govern the site-specific attachment of ThT in the plasmonic hotspot. Au newlineNBPs were selected as the anisotropic plasmonic linear nanost