IN-VITRO CALCIFIED TENDON COLLAGEN - AN ATOMIC-FORCE AND SCANNING ELECTRON-MICROSCOPY INVESTIGATION

Atomic force microscopy (AFM), scanning electron microscopy and X-ray energy dispersive spectroscopy have been performed on decalcified turk ey tendons submitted to in vitro calcification in order to investigate the morphology and the surface relationships between the inorganic ph ase and the collagen fibres during deposition and compare with those f ound for physiologically calcified samples. 'Tapping mode' AFM was use d to reduce the vertical force applied to the samples, which were exam ined without any preparation. A further characterization has been carr ied out by means of X-ray diffraction, infrared absorption and chemica l analyses. The observations indicate that the inorganic phase deposit ed on collagen fibres during in vitro calcification is poorly crystall ine B carbonated apatite. The composition, structure and dimensions of apatitic crystallites, as well as their orientation with respect to c ollagen fibrils, are very similar to those characteristic of physiolog ically calcified tissues. However, the crystallites seem to be nucleat ed on the fibril surface, without appreciably affecting the molecular packing of collagen. (C) 1997 Published by Elsevier Science Limited.