Biaxial mechanical/structural effects of equibiaxial strain during crosslinking of bovine pericardial xenograft materials

Shari E. Langdon, Robert Chernecky, Christopher A. Pereira, David Abdulla, Lee J Michael

Producción científica: Contribución a una revistaArtículorevisión exhaustiva

66 Citas (Scopus)

Resumen

We have investigated the effect of biaxial constraint during glutaraldehyde crosslinking on the equibiaxial mechanical properties of bovine pericardium. Crosslinking of cruciate samples was carried out with: (i) no applied load, (ii) an initial 25 g (~ 30 kPa) equibiaxial load, or (iii) an initial 200 g (~ 250 kPa) equibiaxial load. All loading during crosslinking was done under a defined initial equibiaxial load and subsequently fixed biaxial strain. Load changes during crosslinking were monitored. Mechanical testing and constraint during crosslinking were carried out in a custom-built biaxial servo-hydraulic testing system incorporating four actuators with phase-controlled waveform synthesis, high frame-rate video dimension analysis, and computer-interfaced data acquisition. The paired biaxial stress-strain responses under equibiaxial loading at 1 Hz (before and after treatment) were evaluated for changes in anisotropic extensibility by calculation of an anisotropy index. Scanning electron microscopy (SEM) was performed on freeze-fractured samples to relate collagen crimp morphology to constraint during crosslinking. Fresh tissue was markedly anisotropic with the base-to-apex direction of the pericardium being less extensible and stiffer than the circumferential direction. After unconstrained crosslinking, the extensibility in the circumferential direction, the stiffness in the base-to-apex direction, and the tissue's anisotropy were all reduced. Anisotropy was preserved in the tissue treated with an applied 25 g load; however, tissue treated with an applied 200 g load became extremely stiff and nearly isotropic. SEM micrographs correlated well with observed extensibility in that the collagen fibre morphology changed from very crimped (unconstrained crosslinking), to straight (200 g applied load). Biaxial stress-fixation may allow engineering of bioprosthetic materials for specific medical applications.

Idioma originalEnglish
Páginas (desde-hasta)137-153
Número de páginas17
PublicaciónBiomaterials
Volumen20
N.º2
DOI
EstadoPublished - ene. 1999

Nota bibliográfica

Funding Information:
The authors wish to express their thanks to the staff, Canada Department of Agriculture, and Grober Farms, Cambridge, Ontario for their assistance in the harvesting of intact bovine hearts and pericardia. Thanks are also expressed to Dr. Tack Lam, Jodie Moran, and Verma Miera for assistance with set-up and hardware validation of the biaxial testing system. This work was supported by equipment, operating, and post-graduate scholarship grants from the Natural Sciences and Engineering Research Council of Canada (NSERC) and by contract support from the Ontario Centre for Materials Research (OCMR).

ASJC Scopus Subject Areas

  • Bioengineering
  • Ceramics and Composites
  • Biophysics
  • Biomaterials
  • Mechanics of Materials

PubMed: MeSH publication types

  • Journal Article
  • Research Support, Non-U.S. Gov't

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