Mineralização in vitro de matrizes de colágeno aniônico derivadas de tecidos biológicos / In vitro mineralization of anionic collagen matrices

AUTOR(ES)
DATA DE PUBLICAÇÃO

2008

RESUMO

The reconstruction of osseous defects is still a problem that affects millions of people and medicine tries to solve it. One alternative to solve these problems has been the development of biomaterials that can be used as inductors in the osseous repair process. Collagen is a natural polymer able to promote healing and bone regeneration, and among hydroxyapatite (HA) is the main component found in bone tissue. Several mineralized collagen scaffolds are described in literature, in the form of gel, membranes and films, however, in vitro mineralization of acellular matrices, obtained from biological tissues without the loss of collagenic structure, has not been reported. The objective of this work was the mineralization and characterization of anionic collagen matrices obtained from porcine skin, bovine pericardium and porcine serosa. Biological tissues were treated at room temperature for 0-96h in alkaline solution and mineralized by alternate soaking method. Materials were characterized by preliminary assay of in vitro cytotoxicity, differential scanning calorimetry (DSC), termogravimetric analysis (TG/DTG), scanning electronic microscopy (SEM), energy dispersive x-ray analysis (EDS), x-ray diffraction (XRD), and Fourier Transform Infrared Spectroscopy (FTIR). No cytotoxicity was observed in any of the evaluated matrices; however, a pre-treatment of porcine skin matrices, for fat removal, was necessary. DSC results showed the integrity of collagen matrices after alkaline treatment. Denaturation temperature is dependent of time of alkaline treatment, and this effect is greater for porcine skin matrix, followed by bovine pericardium and porcine serosa. TG/DTG curves showed weight losses associated with release of water, degradation of protein structure and combustion of residual organic components. Residues were obtained at 750°C and associated to hydroxyapatite, being porcine serosa matrix the most mineralized. All mineralized matrices showed an increase in collagen thermal stability when compared to hydrolyzed matrices. FTIR spectra showed the presence of phosphate ions and the interaction of calcium ions with collagen. Ca/P ratios obtained by EDS were as expected when compared with literature values for HA, and RDX results confirmed amorphous HA as the main mineralization product. MEV analysis showed that collagen fibers were more affected for longer hydrolysis times, and that salt deposition was heterogeneous, with crystals grouped in spherical agglomerates in a needle-like shape throughout surface and inner, except for porcine skin derived matrices that were not internally mineralized due their width. Obtained results demonstrated that in vitro mineralization of type I collagen matrices, using different sources of biological tissues and hydrolysis time was possible, producing a material with potential to be used in bone regeneration.

ASSUNTO(S)

mineralization hydroxyapatite hidroxiapatita colágeno mineralização collagen

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