Tesis doctoral de Marta Pegueroles Neyra
The aim of this phd thesis is to gain an increased understanding of the material-biosystem interactions, with an emphasis on establishing correlations between surface properties of titanium surfaces and its in vitro biological response. commercially pure titanium (c.P. Ti) is being widely and successfully used implant biomaterial in bone surgery over many years. Its excellent biocompatibility is based in its appropriate mechanical properties and, more importantly, in its excellent corrosion resistance. Smooth/polished and rough c.P. Ti surfaces obtained by blasting with abrasive particles of different chemical composition (al2o3 and sic) and different sizes (212-300µm; 425-600µm; 1000-1400mm) were studied. the comprehensive characterization of physical and chemical surface properties, including roughness, chemical composition, wettability/free energy and electrical charge of the tested surfaces led to a series of relevant conclusions. Among them, it is worth noting that a) the chemical composition of the grit-blasting particles as well as the method of sterilization were found the main factors influencing wettability and surface free energy of the titanium surfaces; b) the sterilization method changed the electron donor character of the surfaces by changing the amount/nature of physisorbed substances on the surfaces, and c) the chemical composition of the blasting particles did not influence on the electrical charge at physiological ph and the isoelectric point of the surfaces. a second step consisted in the use of a quartz crystal microbalance with monitoring of the energy dissipation to study the adsorption kinetics (amount and conformat ion) and adsorption competition processes of three proteins of special interest in the healing processes of bone -bovine serum albumin (bsa), fibrinogen (fbg), and fibronectin (fn) – on smooth tio2-coated sensors. Fluorescent labelling techniques where used to study protein adsorption on blasted rough surfaces. Most significantly, the amount of fn and bsa adsorbed on blasted surfaces was positively correlated with their surface energy. the adsorption of fibronectin from solution on shot-blasted rough titanium surfaces resulted in an irregular pattern of adsorption. further, the spatial organization of the osteoblast extracellular matrix, ecm, on smooth and rough ti surfaces was evaluated by visualizing fluorescently-stained fn-fibrils. Osteoblast-like cells deposited fn- fibrils in a specific facet -like pattern that was organized within the secreted total matrix. It appeared as a film overlying the top of the different rough titanium surfaces. Interestingly, the thickness of this layer increased with the roughness of the underlying topography, but no more than half of the total maximum peak-to-alley distance was covered. finally, taking into consideration the differences in ecm organization and fn adsorption on the tested ti surfaces a qrt-pcr study was carried out to elucidate the influence of titanium surface properties with and without fn-precoatings on the osteoblast response. The expression of a5 integrin subunit gene, as a marker for cell adhesion, was increased in sic-blasted surfaces compared to alumina-blasted surfaces. the increase of roughness as well as the presence of alumina particles on blasted surfaces increased alp activity and alp mrna gene expression by osteoblasts, and so their differentiation. this research work contribute to increase our knowledge on the interactions taking place at the bio/non- bio interface between different biological components -water, proteins, cells- and materials of clinical relevance, such as rough titanium. The intertwined effects of the different properties of the s ynthetic surfaces appear as a challenge to unravel the ultimate causes that determine the fate of cells on synthetic biomaterials.
Datos académicos de la tesis doctoral «Interactions between titanium surfaces and biological components«
- Título de la tesis: Interactions between titanium surfaces and biological components
- Autor: Marta Pegueroles Neyra
- Universidad: Politécnica de catalunya
- Fecha de lectura de la tesis: 16/09/2009
Dirección y tribunal
- Director de la tesis
- Conrado Jose Aparicio Badenas
- Tribunal
- Presidente del tribunal: María pau Ginebra molins
- george Altankov (vocal)
- (vocal)
- (vocal)