Influence of Surfactant Bilayers on the Refractive Index Sensitivity and Catalytic Properties of Anisotropic Gold Nanoparticles

Date
2016
Authors
Martinsson, Erik
Shahjamali, Mohammad M.
Large, Nicolas
Zaraee, Negin
Zhou, Yu
Schatz, George C.
Mirkin, Chad A.
Aili, Daniel
Journal Title
Journal ISSN
Volume Title
Publisher
Wiley
Abstract

Shape-controlled synthesis of gold nanoparticles generally involves the use of surfactants, typically cetyltrimethylammonium (CTAX, X = Cl−, Br−), to regulate the nucleation growth process and to obtain colloidally stable nanoparticles. The surfactants adsorb on the nanoparticle surface making further functionalization difficult and therefore limit their use in many applications. Herein, the influence of CTAX on nanoparticle sensitivity to local dielectric environment changes is reported. It is shown, both experimentally and theoretically, that the CTAX bilayer significantly reduces the refractive index (RI) sensitivity of anisotropic gold nanoparticles such as nanocubes and concave nanocubes, nanorods, and nanoprisms. The RI sensitivity can be increased by up to 40% by removing the surfactant layer from nanoparticles immobilized on a solid substrate using oxygen plasma treatment. This increase compensates for the otherwise problematic decrease in RI sensitivity caused by the substrate effect. Moreover, the removal of the surfactants both facilitates nanoparticle biofunctionalization and significantly improves their catalytic properties. The strategy presented herein is a simple yet effective universal method for enhancing the RI sensitivity of CTAX-stabilized gold nanoparticles and increasing their potential as transducers in nanoplasmonic sensors, as well as in catalytic and biomedical applications.

Description
This is the peer reviewed version of the following article: Martinsson, E., Shahjamali, M. M., Large, N., Zaraee, N., Zhou, Y., Schatz, G. C., . . . Aili, D. (2016). Influence of Surfactant Bilayers on the Refractive Index Sensitivity and Catalytic Properties of Anisotropic Gold Nanoparticles. Small, 12(3), 330-342, which has been published in final form at https://doi.org/10.1002/smll.201502449. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived Versions. This article may not be enhanced, enriched or otherwise transformed into a derivative work, without express permission from Wiley or by statutory rights under applicable legislation. Copyright notices must not be removed, obscured or modified. The article must be linked to Wiley’s version of record on Wiley Online Library and any embedding, framing or otherwise making available the article or pages thereof by third parties from platforms, services and websites other than Wiley Online Library must be prohibited.
Keywords
catalysis, cetyltrimethylammonium, finite-difference time-domain (FDTD), localized surface plasmon resonance (LSPR), oxygen plasma
Citation
Martinsson, E., Shahjamali, M. M., Large, N., Zaraee, N., Zhou, Y., Schatz, G. C., . . . Aili, D. (2016). Influence of Surfactant Bilayers on the Refractive Index Sensitivity and Catalytic Properties of Anisotropic Gold Nanoparticles. Small, 12(3), 330-342. doi:https://doi.org/10.1002/smll.201502449
Department
Physics and Astronomy