The role of the amorphous phase on the biomimetic mineralization of collagen.
Bone is a hierarchically structured composite material whose basic building block is the mineralized collagen fibril, where the collagen is the scaffold into which the hydroxyapatite (HA) crystals nucleate and grow. Understanding the mechanisms of hydroxyapatite formation inside the collagen is key to unravelling osteogenesis. In this work, we employed a biomimeticin vitromineralization system to investigate the role of the amorphous precursor calcium phosphate phase in the mineralization of collagen. We observed that the rate of collagen mineralization is highly dependent on the concentration of polyaspartic acid, an inhibitor of hydroxyapatite nucleation and inducer of intrafibrillar mineralization. The lower the concentration of the polymer, the faster the mineralization and crystallization. Addition of the non-collagenous protein C-DMP1, a nucleator of hydroxyapatite, substantially accelerates mineral infiltration as well as HA nucleation. We have also demonstrated that Cu ions interfere with the mineralization process first by inhibiting the entry of the calcium phosphate into the collagen, and secondly by stabilizing the ACP, such that it does not convert into HA. Interestingly, under these conditions mineralization happens preferentially in the overlap regions of the collagen fibril. Our results show that the interactions between the amorphous precursor phase and the collagen fibril play an important role in the control over mineralization.
Laboratory of Materials and Interface Chemistry and Soft Matter CryoTEM Unit, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, The Netherlands. ; Tel: 31 40 247 5870.
Fabio
F
Nudelman
Laboratory of Materials and Interface Chemistry and Soft Matter CryoTEM Unit, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, The Netherlands. ; Tel: 31 40 247 5870.
Paul H H
PH
Bomans
Department of Oral Biology, University of Illinois, Chicago, USA. ; Tel: +1 312 413 0738.
Anne
A
George
Laboratory of Materials and Interface Chemistry and Soft Matter CryoTEM Unit, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, The Netherlands. ; Tel: 31 40 247 5870.
Gijsbertus
G
de With
Laboratory of Materials and Interface Chemistry and Soft Matter CryoTEM Unit, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, The Netherlands. ; Tel: 31 40 247 5870.
Nico A J M
NA
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