Surface study of collagen/poloxamine hydrogels by a 'deep freezing' ToF-SIMS approach

Biomaterials. 2006 Apr;27(11):2340-8. doi: 10.1016/j.biomaterials.2005.11.028. Epub 2005 Dec 5.

Abstract

In order to determine the presence of collagen molecules at the surface of a collagen-modified poloxamine hydrogel (a semi-interpenetrating network), the surface composition was studied using Time-of-Flight Secondary Ion Mass Spectra (ToF-SIMS). Collagen was added to the poloxamine hydrogel (poloxamine is a commercially available four-arm poly(ethylene oxide)/poly(propylene oxide) block copolymer, PEO/PPO) to promote the attachment of endothelial or liver cells. X-ray photoelectron spectroscopy (XPS) of dry samples showed a sharp increase in the N content from 0.6% in a pure poloxamine hydrogel to 8.8% in the collagen-containing material. Afterwards, the surface was studied by a 'deep freezing' ToF-SIMS approach under progressive heating from -120 to -60 degrees C. The positive spectrum of collagen/poloxamine at -65 degrees C displayed distinct signals corresponding to different amino acid fragments such as CH4N+ (30 m/z, Gly), C3HN2+ (43 m/z, Arg), C2H6N+ (44 m/z, Ala) and C4H5N2+(81m/z, His) and others corresponding to the PEO and PPO blocks of poloxamine. In addition, the negative spectrum showed peaks at 26 m/z (CN-), 32 m/z (S-) and 42 m/z (CNO-) characteristic of fragments of the collagen molecule. Imaging experiments indicated the homogeneous distribution of the collagen on the surface. These results supported the use of ToF-SIMS for the surface characterization of hydrated hydrogels and confirmed the collagen presence as the means whereby cells attach to the modified poloxamine matrix.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Biocompatible Materials / chemistry*
  • Cattle
  • Cell Adhesion
  • Cells, Cultured
  • Collagen / chemistry*
  • Ethylenediamines / chemistry*
  • Freezing
  • Hydrogels / chemistry
  • In Vitro Techniques
  • Materials Testing
  • Microscopy, Fluorescence
  • Molecular Structure
  • Spectrometry, Mass, Secondary Ion / instrumentation
  • Spectrum Analysis
  • Surface Properties
  • Surface-Active Agents / chemistry
  • X-Rays

Substances

  • Biocompatible Materials
  • Ethylenediamines
  • Hydrogels
  • Surface-Active Agents
  • Tetronic 1107
  • Collagen