Issue 2, 2016

Nanostar probes for tip-enhanced spectroscopy


To overcome the current limit of tip-enhanced spectroscopy that is based on metallic nano-probes, we developed a new scanning probe with a metallic nanostar, a nanoparticle with sharp spikes. A Au nanoparticle of 5 nm was first attached to the end of a tip through DNA–DNA hybridization and mechanical pick-up. The nanoparticle was converted to a nanostar with a core diameter of ∼70 nm and spike lengths between 50 nm and 80 nm through the reduction of Au3+ with ascorbic acid in the presence of Ag+. Fabrication yields of such tips exceeded 60%, and more than 80% of such tips showed a mechanical durability sufficient for use in scanning microscopy. Effectiveness of the new probes for tip-enhanced Raman scattering (TERS) and tip-enhanced fluorescence (TEF) was confirmed. The probes exhibited the necessary enhancement for TEF, and the tip-on and tip-off ratios varied between 5 and 100. This large tip-to-tip variability may arise from the uncontrolled orientation of the apexes of the spike with respect to the sample surface, which calls for further fabrication improvement. The result overall supports a new fabrication approach for the probe that is effective for tip-enhanced spectroscopy.

Graphical abstract: Nanostar probes for tip-enhanced spectroscopy

Supplementary files

Article information

Article type
25 Sep 2015
24 Nov 2015
First published
26 Nov 2015
This article is Open Access
Creative Commons BY license

Nanoscale, 2016,8, 987-994

Nanostar probes for tip-enhanced spectroscopy

W. Kim, N. Kim, J. W. Park and Z. H. Kim, Nanoscale, 2016, 8, 987 DOI: 10.1039/C5NR06657C

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