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Watzy, Murielle

Date Created



Gold and silver nanoparticles have been used since antiquity because of their unique optical properties (Amendola, Pilot, Frasconi, Mrago, & Lati, 2017) . These properties are related to a phenomenon called localized surface plasmon resonance (LSPR), which is the collective oscillation of electrons located within the conduction band of a metal upon excitation by light at a specific frequency (Amendola et al., 2017). The extinction cross section, which defines the amount of incident light scattered or absorbed by a solution, that is related to the LSPR of gold and silver nanoparticles is up to five times greater than those of standard organic dyes (Jain, Lee, El-Sayed, & El- Sayed, 2006). In addition, the LSPR of gold and silver nanoparticles is highly tunable with changes in the morphology (Jain et al., 2006) or the dielectric environment (Evanoff, & Chumanov 2004). Gold and silver nanoparticles have thus been developed for biosensing applications. However, many of these methods still remain limited in terms of sensitivity and use (Rodriguez-Lorenzo, De La Rica, Alvarez-Puebla, Liz-Marzan, & Stevens, 2017). One recent and promising candidate comes in the form of gold-silver core-shell nanoparticles; this is due to their unique LSPR modes that undergo a significant band shift upon deposition of the silver shell (Zhang, Chen, & Li, 2015). The research covered in this work looks at the optimization of several key properties related to the deposition of a silver shell onto a gold core that are necessary for biosensing applications. This includes the reproducibility of the gold-core synthesis, the development of a gold seed purification method, the kinetic study of the silver shell deposition, and the observable features of the silver shell growth in the presence of citrate. Finally, the feasibility of this method is also investigated with a “proof of concept” application in which four plant-based polyphenols are used to reduce a silver shell on a gold core.


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