Adsorption of bisphosphonates and proteins on TiO2 surfaces for bone implants
Deposition and surface functionalization of TiO2 thin films prepared by RF sputtering
Study of hydroxyapatite and TiO2 thin films surface functionalized with bisphospho...
Full text | |
Author(s): |
Orisson Ponce Gomes
Total Authors: 1
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Document type: | Master's Dissertation |
Press: | Bauru. 2019-04-10. |
Institution: | Universidade Estadual Paulista (Unesp). Faculdade de Ciências. Bauru |
Defense date: | 2019-03-28 |
Advisor: | Paulo Noronha Lisboa Filho |
Abstract | |
Nanostructured titanium dioxide (TiO2) has been used as a surface modifier in medical implants, promoting improved biocorrosion resistance of the material and increased bioactivity, presenting promising results in the interaction with the living tissue. Despite the biocompatibility of this oxide is recognized, there are still many aspects of the adhesion mechanisms between the proteins and the material surface that are not completely understood. Chemically, the surface of these oxides is mainly terminated by -OH groups which can be readily functionalized. This chemical functionalization or simply a physical modification of the material surface can improve the interaction between the oxide and the biological environment. In addition, titanium dioxide may have the number of hydroxyl groups increased by physical induction under exposure to ultraviolet light. Although this hydroxylation process is less stable, it is possible to increase the number of active sites for a more efficient functionalization. Although the groups generated by this process are thermodynamically less stable, the greater number of active sites available to bound to organic molecules can result in a more efficient functionalization. In this work, the adsorption conformational studies of three different bifunctional molecules, 3-mercaptopropionic acid (MPA), 3-aminopropyltrimethoxysilane (APTMS) and 3-(4-aminophenil) propionic acid (APPA), are presented. These molecules act as spacers in the protein immobilization process on the physically hydroxylated surfaces of TiO2 films. The TiO2 films were grown on grade IV metallic titanium substrates by Reactive RF Magnetron Sputtering technique. XPS results showed greater efficiency in the immobilization of APTMS molecule on the hydroxylated surface of TiO2 in comparison to MPA and APPA molecules. In addition, the APTMS molecule also showed satisfactory results in the immobilization of bovine serum albumin (BSA) protein. Results regarding viability tests, cell adhesion and expression of genes related to cell adhesion after direct contact with bone cells showed better interaction of the surface modified by the immobilization of BSA when intermediated by APTMS molecule. Bone cells in direct contact with this surface showed greater expression of the genes related to the initial stage of osteoblastic differentiation with respect to cells in direct contact with the surface whose albumin was immobilized directly on TiO2 surface. Results obtained by zymography also corroborated with those presented by gene expression, given the involvement of MMP2 and MMP9 in the process of osteoblastic differentiation. (AU) | |
FAPESP's process: | 16/22186-7 - Protein Interaction in TiO2 Thin Films Surfaces |
Grantee: | Orisson Ponce Gomes |
Support Opportunities: | Scholarships in Brazil - Master |