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Mechanical properties of extracellular matrix/hydroxyapatite composites

L. PRAMATAROVA1, E. PECHEVA1, M. DIMITROVA1,* , A. PETROVA2, P. MONTGOMERY3, T. PETROV1

Affiliation

  1. Institute of Solid State Physics, Bulgarian Academy of Sciences, 72 Tzarigradsko Chaussee Blvd., 1784 Sofia
  2. Space Research Institute, Bulgarian Academy of Sciences, Sofia, 72 Tzarigradsko Chaussee Blvd., 1784 Sofia
  3. Institut d'Electronique du Solide et des Systemes (InESS), CNRS-ULP UMR7163, 23 rue du Loess, 67037 Strasbourg, France

Abstract

An increasing interest in biomimetics – design of materials based on natural biological structures - has led to the nanomechanical characterization of biomaterials. In this regard, nanoindentation has been used in conjunction with the determination of the mechanical properties of the extracellular matrix (ECM) proteins that are known as ligands in reactions with cell surface receptors involved in bone physiology. The aim of the presented work is to investigate the - and nano-scale mechanical properties of laser designed extracellular matrix/hydroxyapatite composites. The osteoblast-like cell line SAOS-2 synthesised and assembled its own ECM on the solid substrates under standard cell culture conditions. After selective removal of cells, thin films of ECM on substrates of stainless steel (SS), silicon (S) and silica glass (SG) were obtained. One group of samples was soaked in simulated body fluid (SBF) and another was obtained by simultaneous immersion in the SBF and treatment by laser irradiation. As a result, a hydroxyapatite (HA) crystal layer was grown on the surfaces. The mechanical properties of the obtained composites, such as elastic modulus (E) and indentation hardness (H), were analysed. It was observed that by applying a typical working force in the range 200 μN to 600 μN and a displacement range of 0-60 μm, E increased for all composites obtained by the laser process (for samples immediately removed from the SBF). Surface scanning along the direction centre of the sample to the laser treated area showed a decrease in the Young’s modulus, to values similar to those in the human bone..

Keywords

Extracellular matrix, Mechanical properties, Hydroxyapatite, Laser-liquid-solid-interaction process.

Submitted at: Nov. 28, 2006
Accepted at: Jan. 15, 2007

Citation

L. PRAMATAROVA, E. PECHEVA, M. DIMITROVA, A. PETROVA, P. MONTGOMERY, T. PETROV, Mechanical properties of extracellular matrix/hydroxyapatite composites, Journal of Optoelectronics and Advanced Materials Vol. 9, Iss. 1, pp. 229-232 (2007)