Eur. Phys. J. E 6, 7-14 (2001)
The interplay between surface micro-topography and -mechanics of type I collagen fibrils in air and aqueous media: An atomic force microscopy study
K. Kato, G. Bar and H.-J. CantowFreiburger Materialforschungszentrum and Institut für Makromolekulare Chemie, Albert-Ludwigs-Universität Freiburg, Stefan-Meier-Str. 21, D-79104 Freiburg, Germany cantow@fmf.uni-freiburg.de
(Received 28 March 2000 and Received in final form 15 June 2001)
Abstract
Calf skin type I collagen fibrils were regenerated from acidic solution and
imaged with contact mode atomic force microscopy in air, water, and buffer
solution. When imaged in air at a contact force of 20-150 nN, collagen
fibrils exhibited a distinct transverse banding pattern with a period of 65
nm, consisting of high ridges and shallow grooves. The force dependence of
the images suggests that such banding pattern is attributed to the
transverse contraction of the fibril upon dehydration during sample
preparation, which reflects the tangential mass density across the fibril.
Imaging in water and phosphate buffer solution at a contact force of 15-80
nN revealed hydrated collagen fibrils with smooth surfaces. The rigidity of
the collagen fibrils decreased considerably upon hydration. Scanning the
cantilever tip in an aqueous medium at a contact force of 90-280 nN enabled
us to probe subunit arrangement in the bulk region of the collagen fibril.
The results indicate that the molecular assembly in the hydrated fibril is
akin to that in the intact form. The image resolution was improved by
stabilizing the collagen molecules through crosslinking with glutaraldehyde,
which served to resolve microfibril-like structure on the fibril surface.
87.64.Dz - Scanning tunneling and atomic force microscopy.
87.16.Ka - Filaments, microtubules, their networks, and supramolecular assemblies.
87.14.Ee - Proteins.
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag 2001
