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The inside of a time-of-flight secondary ion mass spectrometer (ToF-SIMS) instrument. The end of the ion gun, analyzer lens and charge neutralizer along with the sample stage are visible.

National ESCA and Surface Analysis Center for Biomedical Problems

Contents

• Contact Information
• Grant Number
• Research Emphasis
• Current Research 
• Resource Capabilities
• References 

Contact Information

University of Washington
Departments of Bioengineering and Chemical Engineering
Box 351750
Seattle, WA 98195-1750
http://www.nb.engr.washington.edu

Principal Investigator/Contact
David G. Castner, Ph.D.
Phone: 206-543-8094
Fax: 206-543-3778
castner@nb.engr.washington.edu

Assistant Director
Lara J. Gamble, Ph.D.
Phone: 206-616-4173
Fax: 206-543-3778
gamble@nb.engr.washington.edu

Administrative Contact
Mady F. Lund 
Phone: 206-685-1229
Fax: 206-543-3778
lund@nb.engr.washington.edu

Grant Number

Grant No. EB002027

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Research Emphasis

The National ESCA and Surface Analysis Center for Biomedical Problems (NESAC/BIO) provides state-of-the-art surface analysis expertise, instrumentation, experimental protocols, and data analysis methods to address surface-related biomedical problems. NESAC/BIO develops and applies surface science methodologies that produce a full understanding of the surface composition, structure, spatial distribution, and orientation of biomaterials and adsorbed biomolecules. The NESAC/BIO program identifies areas where surface science must evolve to keep pace with the growth in biochemical knowledge and biomaterial fabrication technology, and develops instrumentation, experimental protocols, and data analysis methods to achieve this evolution.

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Current Research

Current NESAC/BIO research projects include surface chemical state imaging and characterization of complex biological surfaces. A complementary analysis approach of electron spectroscopy for chemical analysis (ESCA), time-of-flight static secondary ion mass spectrometry (ToF-SIMS), scanning force microscopy (SFM), near edge x-ray absorption fine structure (NEXAFS), sum frequency generation (SFG) vibrational spectroscopy and surface plasmon resonance (SPR) biosensing is used.

The chemical state imaging research objectives are to: identify all surface chemical components; identify all chemically distinct surface regions; quantitatively determine the composition of each region; and optimize spatial resolution. The objectives for the characterization of complex biological surfaces are to develop new experimental techniques, multivariate data analysis methods, and sample preparation strategies for studying the structure of immobilized biomolecules.

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Resource Capabilities

The surface analysis methods currently available on site at NESAC/BIO are ESCA, SIMS, SPR and SFM. NEXAFS experiments are done off-site at one of the national synchrotron facilities.  Construction of an on-site SFG system is planned for 2006. ESCA provides quantitative surface (100 Å) elemental composition along with information about the bonding environment of each element. Angle-dependent ESCA is available for nondestructive compositional profiling of the surface region. Hydrated materials can be examined using in situ freeze-drying. ESCA images can be obtained with spatial resolutions down to 10 microns. Static SIMS provides mass spectra and images of the outermost 2 nm of a sample. From the positive and negative secondary ions detailed molecular structural information about the sample surface can be obtained with high sensitivity (ppm to ppb), high mass resolution (m/m >5000) and spatial resolutions down to a few microns. SFM provides information about surface topography, roughness, atomic/molecular scale structure, and overlayer film thickness. SFM experiments can be done in either air or liquid environments. SPR provides quantitative information about the amount and kinetics of biomolecule attachment to surfaces from various liquid environments. The NEXAFS experiments provide information about the electronic structure of films and can be used to determine the orientation and ordering of surface species.  In addition, imaging NEXAFS experiments can be done at spatial resolutions down to 50 nanometers. SFG provides molecular structure information about surface species at solid-liquid, solid-gas and liquid-gas interfaces.

Instruments

• Surface Science Instruments SSX-100 ESCA system (monochromatized x-ray source, variable temperature and angle stages, automated sample analysis)
• Surface Science Instruments S-Probe ESCA system (monochromatized x-ray source, variable temperature and angle stages, automated sample analysis)
• Physical Electronics Model 7200 Time-of-Flight SIMS system with Cs ion source
• Physical Electronics TRIFT II Time-of-Flight SIMS instrument with Ga ion source
• Molecular Imaging PicoSPM scanning force microscope
• Plasmon II Surface Plasmon Resonance system with dual flow chamber
• Kratos Analytical AxisUltra Imaging ESCA system (monochromatized x-ray source, variable temperature and angle stages, automated sample analysis)

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References

1. Castner DG, Ratner BD. Biomedical surface science: foundations to frontiers. Surface Science 2002;500:28-60.
2. Xia N, May CJ, McArthur SL, Castner DG. ToF-SIMS analysis of conformational changes in adsorbed protein films. Langmuir 2002;18:4090-4097.
3. Wagner MS, Castner DG. Analysis of adsorbed protein films by static ToF-SIMS. Applied Surface Science 2004;231-232, 366-376.
4. McArthur SL, Vendettuoli MC, Ratner BD, Castner DG. Methods for generating protein molecular ions in ToF-SIMS. Langmuir 2004;20:3704-3709.
5. Wagner MS, Graham DJ, Ratner BD, Castner DG. Maximizing information obtained from secondary ion mass spectra of organic thin films using multivariate analysis. Surface Science 2004;570:78-97.
6. Canavan HE, Cheng X, Graham DJ, Ratner BD, Castner DG. Surface characterization of the extracellular matrix remaining after cell detachment from a thermoresponsive polymer. Langmuir 2005;21:1949-1955.