Effective surface modification of gold nanorods for localized surface plasmon resonance-based biosensors

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• 作者：Jie Cao^a ; ^b ; ^{jie.cao.1@city.ac.uk}  ; [Author Vitae] ; Ewan K. Galbraith^a  ; [Author Vitae] ; Tong Sun^a  ; [Author Vitae] ; Kenneth T.V. Grattan^a  ; [Author Vitae]
• 关键词：Gold nanorod ; Biosensor ; Localized surface plasmon resonance (LSPR) ; Surface modification ; Ligand-exchange
• 刊名：Sensors and Actuators B ; Chemical
• 出版年：2012
• 期刊代码：161_09254005
• 类别：et
• 出版时间：5 July, 2012
• 卷：169
• 期：Complete
• 页码：360-367
• 文件大小：1190 K

摘要

This paper presents a novel, pH-mediated protocol for the surface modification of gold nanorods (GNRs), which provides a robust platform for the assembly of localized surface plasmon resonance (LSPR)-based sensors, by facilitating functionalization at the surface of the nanoparticles. This is achieved by replacing the surface bilayer of cetyltrimethylammonium bromide (CTAB) with 11-mercaptoundecanoic acid (MUA) at alkaline pH after seed-mediated growth of GNRs. This method fully exploits the characteristics of MUA (i) the carboxylic acid functionality enables ligand exchange in an aqueous environment; (ii) the hydrophobic nature of the molecule stabilizes the nanorods and prevents aggregation via a self-assembled monolayer and (iii) the sulfur moiety binds to the gold surface. Critically, this procedure also simplifies subsequent functionalization, overcoming the limitation arising from commonly used CTAB-only preparation. XPS (X-ray photoelectron spectroscopy) was used to confirm the ligand exchange at the surface of the GNRs. The surface modification facilitates the preparation of a LSPR-based biosensor based on human IgG for the detection of anti-human IgG and a detection limit of 0.4 nM was observed.