AVS 53rd International Symposium
    Biomaterial Interfaces Thursday Sessions
       Session BI+AS-ThA

Paper BI+AS-ThA3
Analysis of In-Vitro Biomineralization Processes Quantitatively by Quartz Crystal Microbalance (QCM)- and Transmission Electron Microscopic (TEM)- Explorations

Thursday, November 16, 2006, 2:40 pm, Room 2014

Session: Biomolecule-Surface Characterization I
Presenter: U. Plate, Universitaet Muenster, Germany
Authors: U. Plate, Universitaet Muenster, Germany
Ch. Mentrup, Universitaet Muenster, Germany
H.J. Hoehling, Universitaet Muenster, Germany
Correspondent: Click to Email
The primary crystallites of different developing hard tissues describe an apatitic structure with crystal lattice fluctuations representing an intermediate state between amorphous and fully crystalline. Some non-collagenous proteins (NCPs) bound immobilized at the surface of collagen type I are implicated in the initiation and regulation of crystal formation and growth. In the investigations we have induced synthetic biomineralization processes. Collagenous matrices were reconstituted in-vitro and Phosvitin, a Phosphoprotein from an eggshell, were used (concentration 6 mg/ml in 0,3M Na@sub 2@CO@sub 3@). Phosvitin was cross-linked to collagen type I fibrils (concentration 0,25 mg/ml in 0,05M HAc) with Divinylsulfon (DVS). Dynamic in-vitro biomineralization processes at this matrices, pure collagen and Collagen-DVS-Phosvitin, were induced by contacting their surfaces with defined inorganic Ca- and PO@sub 4@-solutions. Qualitative and quantitative measurements were achieved in an in-vitro model for Quartz Crystal Microbalance (QCM)- and Transmission Electron Microscopic (TEM)- explorations. To locate the organic matrix for QCM- and TEM- measurements statistically, the Au-surfaces on the quartz- and TEM-grids were functionalised with thiols containing chain-length carboxylic-acid groups, in the experiences 10 µmM carboxylic-acid thiols with a mercaptopropyl group. This carboxylic-acid groups form self assembling monolayers (SAMs) and are utilized for the modification of an Au-surface to introduce carboxylic groups on it. Then the carboxylic groups are converted to amines of biomaterials. To induce biomineralisation processes 2,2 mM CaCl@sub 2@- and 1,3 mM K@sub 2@HPO@sub 4@-solutions were pumped along the matrices in defined time intervals with a peristaltic pump. The experiments were carried out in a chamber under native conditions (T = 37°C, pump velocity of the Ca-phosphate solutions of 1,62 ml/min, comparable to the fluid flux of blood in capillaries.).