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Immobilization of phosphate monomers on collagen induces biomimetic mineralization.
Biomed Mater Eng. 2015 Jan 1;25(1):89-99
Authors: Nurrohman H, Nakashima S, Takagaki T, Sadr A, Nikaido T, Asakawa Y, Uo M, Marshall SJ, Tagami J
Abstract
BACKGROUND: Immobilization of phosphoproteins on type-I collagen via covalent binding may induce extra- and intrafibrillar mineralization.
OBJECTIVE: This study tested the hypothesis that methacrylate phosphate esters immobilized on reconstituted type-I collagen can mimic the nucleating role of phosphoproteins.
METHODS: Three functional monomers (MDP, GPDM and Phenyl-P) that differed in chemical structure and steric hindrances around the phosphate moiety were evaluated. Reconstituted type-I collagen was either left untouched (control) or treated by 5% monomer/ethanol for 20 s. All samples were incubated in simulated dentinal fluid as mineralizing medium at 37°C for 7 or 14 days. The extra- and intrafibrillar mineralization were examined by SEM and TEM/SAED crystallography, respectively.
RESULTS: FT-IR spectroscopy showed that the phosphate groups were incorporated on reconstituted collagen, irrespective of their chemical structure. MDP immobilization induced dense growth of extrafibrillar mineral over time, while with GPDM- and Phenyl-P-immobilized collagen, mineralization was moderate and sparse, respectively. TEM/SAED evidence disclosed that intrafibrillar minerals exclusively occurred in MDP-immobilized collagen.
CONCLUSIONS: Immobilization of MDP, which had the lowest steric hindrance, could induce significant biomimetic extra- and intrafibrillar mineralization; resembling the lowest level of hierarchy organization of dentin.
[cite source='pubmed']25585983[/cite] – in process]