The Plasmon Resonance of a Multilayered Gold Nanoshell and its Potential Bioapplications

The optical spectra and near-field enhancement of a multilayered gold nanoshell were theoretically studied in this paper to explore its potential biological applications. The mathematical model was developed within the framework of multipole expansion of a multilayered concentric sphere. Results show that compared with a conventional single-layered Au-SiO₂ nanoshell, a multilayered Au-SiO₂-Au nanoshell has an advantage of realizing the localized surface plasmon resonance at wavelength of 1300 nm or longer, which is believed to be more beneficial to ultrahigh resolution optical coherent imaging. With single-layered nanoshell, an extremely thin gold layer is required for resonance at long wavelength, and making such thin layer would be almost practically impossible within the current synthesis techniques.