Plasmonic nanostructures core/shell/fluorophore: how to control optical properties

Abstract

Many studies focus on dye fluorescence and absorption enhancement near plasmonic nanostructures for the purpose of solving applied problems of nanophotonics and medicine. The strength of these effects depends on the distance between the plasmonic nanoparticle and the fluorophore, and on their optical coupling. The main challenge is to create plasmonic particle/fluorophore nanostructures with variable morphology and controllable dye localization. This work explores the system containing one or two fluorophores in spherical composite nanoparticles (CNPs) with a gold core and a thiolated organosilica shell to investigate the causes and mechanisms in various plasmonic enhancement effects. Moreover, the feasibility of building “cascade” structures of two different fluorophores was studied. We compared two synthesis approaches: introducing the dye during shell growth or attaching it by chemisorption afterward. Key results show that fluorophore emission depends strongly on the distance between dye molecules within the CNP shell and the shell thickness. It is also worth noting that the SH-groups of the organosilica shell allow for the direct chemisorption of fluorophores by thiol/maleimide click-reaction. Note that we detected for the first time the plasmonic enhancement of fluorophore absorption in dispersed nanostructures. The influence of the dye concentration and its distribution within the CNP shell on this effect was evaluated. Additionally, we established the features of embedding of two dyes of different nature in the CNP shell and evaluated the occurrence of Förster resonant energy transfer in this system with quantitative data.

Speaker

Dmitriy Kravchinskiy
A.N.Frumkin Institute of Physical Chemistry and Electrochemistry of the Russian Academy of Sciences, Moscow, Russia
Russia

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