Plasmonic Properties of Anchored Nanoparticles Fabricated by Reactive Ion Etching and Nanosphere Lithography

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• 作者：Erin M. Hicks ; Olga Lyandres ; W. Paige Hall ; Shengli Zou ; Matthew R. Glucksberg ; Richard P. Van Duyne
• 刊名：Journal of Physical Chemistry C
• 出版年：2007
• 出版时间：March 22, 2007
• 年：2007
• 卷：111
• 期：11
• 页码：4116 - 4124
• 全文大小：719K
• 年卷期：v.111,no.11(March 22, 2007)
• ISSN：1932-7455

文摘

Aqueous environments pose unique challenges to the use of nanoparticle platforms for development of robustin vitro and in vivo sensors. A method is developed to anchor nanoparticles into a glass substrate by combiningnanosphere lithography (NSL) and reactive ion etching (RIE) to create a mechanically durable sensing platform.The increased mechanical performance is attributed to the higher adhesion strength of NSL nanoparticlesanchored in shallow nanowells formed by RIE. Using atomic force microscopy (AFM), anchored andconventional NSL nanoparticle arrays were subjected to increasing normal forces. The anchored nanoparticleswere able to withstand normal forces 3 times greater (35.1 nN) compared to the conventional NSL nanoparticles(12.4 nN) prior to separation from the glass substrate. Superior adhesion in a constant flow aqueous environmentis demonstrated by extinction measurements. After 1 h of 1.5 mL/min flow, extinction intensity decreased by53% for bare and 13% for functionalized nanoparticles that were not anchored while extinction intensitydecreased by only 15% for bare and less than 1% for functionalized nanoparticles that were anchored. Asystematic shift to longer wavelengths is observed in the localized surface plasmon resonance (LSPR) spectraof the nanoparticle arrays as the embedded depth increases. This systematic shifting behavior of the LSPRwavelength maximum, mages/gifchars/lambda.gif" BORDER=0 >_max, in the range from 678 to 982 nm, can be used to tune the plasmon position.LSPR shifting is used to demonstrate the detection of Alzheimer's precursor ligands as a potential biosensingapplication of the anchored nanoparticle arrays. Furthermore, we estimate the enhancement factors for SERSof the anchored nanoparticles are on the same order of magnitude (10⁸) as the nanoparticles on flat substrates.Theoretical modeling is conducted to understand the shifting behavior of the anchored nanoparticle arrays.