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Gold Nanoparticle-Enhanced Secondary Ion Mass Spectrometry Imaging of Peptides on Self-Assembled Monolayers

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journal contribution
posted on 15.03.2006, 00:00 by Young-Pil Kim, Eunkeu Oh, Mi-Young Hong, Dohoon Lee, Min-Kyu Han, Hyun Kyong Shon, Dae Won Moon, Hak-Sung Kim, Tae Geol Lee
We demonstrate the use of gold nanoparticles (AuNPs) to enhance the secondary ion emission of peptides in time-of-flight secondary ion mass spectrometry (TOF-SIMS). The signal intensity of peptides adsorbed onto AuNPs was significantly increased when compared to that of self-assembled monolayers (SAMs). This gold nanoparticle-enhanced SIMS, termed NE-SIMS, enabled the sensitive detection of subtle modifications of peptides, such as phosphorylation. From a quantitative analysis of the amounts of adsorbed peptides and AuNPs on SAMs using quartz crystal microbalance and surface plasmon resonance spectroscopy, the ratio of peptide molecule to AuNP on amine-SAMs was revealed to be 18−19:1. When considering the ratio of peptide to matrix (1:103−106) employed in a matrix-enhanced SIMS, the use of AuNPs gave rise to a significantly increased secondary ion emission of peptides. Peptides were adsorbed onto patterned AuNPs on SAMs using a microfluidic system, and well-contrasted molecular ion images were obtained. NE-SIMS is expected to be applied to a chip-based analysis of modification of biomolecules in a label-free manner.