Depth profiling of peptide films with TOF-SIMS and a C60 probe

Juan Cheng, Nicholas Winograd

Research output: Contribution to journalArticlepeer-review

150 Scopus citations

Abstract

A buckminsterfullerene ion source is employed to characterize peptide-doped trehalose thin films. The experiments are designed to utilize the unique sputtering properties of cluster ion beams for molecular depth profiling. The results show that trehalose films with high uniformity can be prepared on Si by a spin-coating technique. Bombardment of the film with C60 + results in high quality time-of-flight secondary ion mass spectrometry spectra, even during ion doses of up to 3 × 1014 ions/cm2. This result is in contrast to atomic bombardment experiments in which the dose of incident ions must be kept below 10 12 ions/cm2 so as to retain mass spectral information. Moreover, since the films are of uniform thickness, it is possible to depth-profile through the film and into the Si substrate. This experimental protocol allows the yield of trehalose molecular equivalents and the degree of interface mixing to be evaluated in detail. When doped with a variety of small peptides up to a molecular weight of m/z 500, we find that the peptide molecular ion intensity remains stable under continuous C60+ bombardment, although some decrease in intensity is observed. The results are interpreted in terms of a model whereby the high trehalose yield and low damage depth of the C60 projectile combine to prevent damage accumulation. In general, the peptide-trehalose system provides a valuable model for evaluating the parameters that lead to effective 3-dimensional characterization of biomaterials.

Original languageEnglish (US)
Pages (from-to)3651-3659
Number of pages9
JournalAnalytical chemistry
Volume77
Issue number11
DOIs
StatePublished - Jun 1 2005

All Science Journal Classification (ASJC) codes

  • Analytical Chemistry

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