| Abstract
| - 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 wassignificantly increased when compared to that of self-assembled monolayers (SAMs). This gold nanoparticle-enhanced SIMS, termed NE-SIMS, enabled the sensitivedetection of subtle modifications of peptides, such asphosphorylation. From a quantitative analysis of theamounts of adsorbed peptides and AuNPs on SAMs usingquartz crystal microbalance and surface plasmon resonance spectroscopy, the ratio of peptide molecule toAuNP on amine-SAMs was revealed to be 18−19:1. Whenconsidering the ratio of peptide to matrix (1:103−106)employed in a matrix-enhanced SIMS, the use of AuNPsgave rise to a significantly increased secondary ion emission of peptides. Peptides were adsorbed onto patternedAuNPs on SAMs using a microfluidic system, and well-contrasted molecular ion images were obtained. NE-SIMSis expected to be applied to a chip-based analysis ofmodification of biomolecules in a label-free manner.
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