Citation
Ferrari, Sandro & Ratner, Buddy D. (2000).
ToF-SIMS quantification of albumin adsorbed on plasma-deposited fluoropolymers by partial least-squares regression.
Surface and Interface Analysis, 29(12), 837-844.
Abstract
Albumin adsorbed on a radiofrequency glow discharge (RFGD) thin film from hexafluoropropylene was characterized by x-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry (ToF-SIMS). The amount of protein adsorbed as a function of the protein concentration was estimated with XPS by following the atomic percentage nitrogen compared to fluorine, carbon and oxygen. The amount of albumin increases steeply between 10−4 and 10−3 mg ml−1 and very slowly thereafter. Intensities of protein-related peaks in the ToF-SIMS spectra are influenced by a matrix effect induced by the fluorinated surfaces. This effect is most pronounced at the lowest protein concentrations. The logarithms of the intensities of the fluorine-containing peaks decrease linearly with increasing protein concentration. Multivariate analysis was used to correlate the data obtained from ToF-SIMS and XPS. Partial least-squares regression was applied using the nitrogen content from XPS as the dependent variable and ToF-SIMS data as the independent variable. A good linear relation is observed using the logarithm of the ToF-SIMS intensities. The ToF-SIMS limitations for quantitative analysis due to the matrix effect, instrumental drift and surface sensitivity are discussed. A comparison of XPS data at different take-off angles with ToF-SIMS data confirms the surface sensitivity of the latter, but also demonstrates that some fluorinated fragments are sampled at depths deeper than might be expected from ToF-SIMS. Copyright © 2000 John Wiley & Sons, Ltd.
Keyword(s)
albuminfluoropolymerquantificationtof-simsxps
Reference Type
Journal Article
Secondary Title
Surface and Interface Analysis
Author(s)
Ferrari, SandroRatner, Buddy D.
Year Published
2000
Date Published
946684800
Volume Number
29
Issue Number
12
Pages
837-844
ISSN/ISBN
1096-9918
DOI
10.1002/1096-9918(200012)29:12<837::aid-sia937>3.0.co;2-o
