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hysical and Chemical Surface Modification of Titanium by Nanostructured Materials, and Biological Characterization for Use in Bone Tissue Implants

Rahnamaee, Yahya | 2020

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  1. Type of Document: Ph.D. Dissertation
  2. Language: Farsi
  3. Document No: 53563 (48)
  4. University: Sharif University of Technology
  5. Department: Materials Science and Engineering
  6. Advisor(s): Bagheri, Reza; Vossoughi, Manochehr; Samadi Kuchaksaraei, Ali
  7. Abstract:
  8. According to human needs and in line with the development of advanced technologies, different biomedical Engineering fields like hard tissue implants are growing rapidly. Despite significant biotechnology Developments in recent years, some problems to the recognition of implants related osseointegration phenomena persist. The deficient osseointegration and implant-associated infections are key issues for the long-term clinical success of titanium and titanium alloy implants, while development of multifunctional surfaces that can simultaneously overcome these problems remains highly challenging. Therefore, the ultimate goal of this paper was to improve bone cell attachment and simultaneously inhibit the bacterial cell adhesion on the implant surface. Therefore, as a result of physical modification, bioinspired multifunctional TiO2 hierarchical micro/nanostructures of conical-shaped TiO2 (CTO), regular TiO2 nanotubes (RTO) and irregular TiO2 nanotubes (ITO) with tunable improved cell growth and inhibited bacteria adhesion were synthesized. On the other hand, with the aim of exploiting the potential of chemical modification for the orthopedic implant, a surface-modified titania nanotubes surface was developed using reduced graphene oxide as well as chitosan nanofibers (CH) coating as a multifunctional nanocomposite. Completely regular titania nanotubes array (cRTNT) with a novel nanostructure was fabricated by the electrochemical anodization, followed by reduced graphene oxide (RGO) deposition. Subsequently, the solvent drop-casting method was employed to create a nanoscale layer of chitosan nanofibers over the RGO-modified surface. The CTO and ITO samples indicated superhydrophilicity with contact angles of less than 5°. The MTT assay demonstrated excellent biological performance for RTO and CTO sample with 98.1% and 103.1% of cell viability, respectively. The number of both Gram-negative Esherichia coli and Gram-positive Staphylococcus aureus bacteria per field (NBPF) for RTO were calculated 31 and 42 respectively which were reduced more than approximately 7 and 6 times compared to the calculated NBPF of 222 and 258 for the untreated RT substrate. It was shown that the chitosan nanocomposite introduced antibacterial properties to the implant surface and prevented bacterial biofilm formation, while at the same time promoted osteoblast MG63 cells proliferation. Furthermore, the surface blocking of nanotube reservoirs in this nanocomposite led to the prolonged antibiotic release profile
  9. Keywords:
  10. Nano-Composite Coating ; Graphene ; Cell Growth ; Anodizing ; Titanium Oxide Nanotube ; Polymer Nanocomposits ; Surface Modification ; Surface Treatment ; Chitosan Nanoparticles ; Hard Tissue Implant

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