Gold-Silver Alloy Plasmonics Nanoparticles: Synthesis, Modelling of Optical Properties and Applications in Hyperspectral Imaging

Michel Meunier Dept of Engineering Physics, Polytechnique Montreal, Montreal, Canada David Rioux Dept of Engineering Physics, Polytechnique Montreal, Montreal, Canada Sergiy Patskovsky Dept of Engineering Physics, Polytechnique Montreal, Montreal, Canada Eric Bergeron Dept of Engineering Physics, Polytechnique Montreal, Montreal, Canada

We report on a new size and composition-controlled synthesis of monodispersed AuAg alloy nanoparticles (NPs) up to 100+ nm based on a seeded growth approach where alloy NPs are grown on small gold seeds. Based on transmission electron microscopy imaging, the size distribution can be as good as 15% over a wide range of sizes and compositions. The alloy composition profile inside the NPs was also obtained and its influence on the optical properties studied. In addition, we have introduced a new model of the dielectric function of these alloy NPs based on the band structures of gold and silver for interband transitions and the Drude model for intraband contributions [1]. Using Mie theory with this dielectric function, the optical absorption and scattering spectra of the NPs as well as the near field amplification can be predicted. These AuAg alloy NPs are promising for chromatic labeling of biological material because of their composition-dependent plasmon resonance. Compared to the conventionally used fluorophores and quantum dots, plasmonic NPs offer the advantage of being highly stable as they do not photobleach nor blink. Our alloy NPs are sufficiently large to assure adequate light scattering for practical imaging applications. This is a clear advantage over the conventional chemical synthesis route where NPs are at most 20-30 nm with controlled size. Hyperspectral imaging is a powerful technique for multiplexed analysis of cells tagged by chromatic biomarkers. We report on a new backscattering approach and instrumentation for fast wide-field hyperspectral imaging of NPs in cellular environment. This approach is very sensitive and, due to the use of high numerical aperture objectives, provides better spatial resolution than standard transmission darkfield [2,3]. The backscattering technique was also used to obtain 3D distribution of plasmonic NPs over the cells [4].

[1] D. Rioux, S. Vallières, S. Besner, P. Muñoz, E. Mazur, and M. Meunier, Adv. Opt. Mater. 2, 176 (2014).

[2] S. Patskovsky, E. Bergeron, and M. Meunier, J. Biophotonics 6, 1 (2013).

[3] S. Patskovsky, E. Bergeron, D. Rioux, M. Simard, and M. Meunier, Analyst, 139 (20), 5247 (2014).

[4] S. Patskovsky, E. Bergeron, D. Rioux, and M. Meunier, J. Biophotonics, (2014).

michel.meunier@polymtl.ca









Powered by Eventact EMS