Publications by authors named "Virpi Aäritalo"

4 Publications

  • Page 1 of 1

Sol-gel-derived TiO(2)-SiO (2) implant coatings for direct tissue attachment. Part I: design, preparation and characterization.

J Mater Sci Mater Med 2007 Sep 17;18(9):1863-73. Epub 2007 May 17.

Department of Prosthetic Dentistry and Biomaterials Research, Institute of Dentistry, University of Turku, Lemminkäisenkatu 2, 20520, Turku, Finland.

A series of sol-gel derived TiO(2)-SiO(2) mixed oxide coatings were prepared by carefully controlling the process parameters to obtain silica-releasing coatings consisting of nanoparticles. These features are of paramount importance for enhanced cell adhesion and activation. To achieve both these goals the Ti-alkoxide and Si-alkoxide were first separately hydrolysed and the titania-silica mixed sol was further reacted before the dipping process to obtain the desired particle sizes resulting to the biologically favourable topographical features. Silica release was observed from all the prepared coatings and it was dependent on SiO(2) amount added to the sols, i.e., the higher the added amount the higher the release. In addition, calcium phosphate was able to nucleate on the coatings. From the obtained SiO(2) dissolution data, together with the detailed XPS peak analysis, the mixed oxide coatings are concluded to be chemically heterogeneous, consisting of TiO(2) and SiO(2) species most likely linked together by Ti-O-Si bonds. TiO(2) is chemically stable making long-term implant coating possible and the desired nanoscale dimensions were well preserved although the composition was changed as a consequence of SiO(2) dissolution under in vitro conditions.
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http://dx.doi.org/10.1007/s10856-007-3062-1DOI Listing
September 2007

Sol-Gel-derived TiO2-SiO2 implant coatings for direct tissue attachment. Part II: Evaluation of cell response.

J Mater Sci Mater Med 2007 Aug;18(8):1633-42

Department of Physical Chemistry, Abo Akademi University, Porthansgatan 3-5, 20500 Turku, Finland.

Silica-releasing sol-gel derived TiO2-SiO2 coatings with tailored nanostructure were evaluated in fibroblast and osteoblast cell cultures. The adhesion of both fibroblasts and osteoblasts proceeded within two hours. The highest fibroblast proliferation activities were observed on the TiO2-SiO2 (70:30) and (30:70) coatings. However, the cell layer on TiO2-SiO2 (30:70) coating was disordered. Prolonged osteoblast activity was observed on the coatings as a function of increased amount of released silica. At day 21 the surfaces were fully covered by the calcified nodules and extracellular matrix except for the coatings TiO2-SiO2 (10:90) i.e. having the highest SiO2 amount. The results suggested that TiO2-SiO2 (70:30) was the best for fibroblasts and TiO2-SiO2 (30:70) for osteoblasts. The applicability of the sol-gel derived TiO2 and TiO2-SiO2 coatings as an alternative for the calcium phosphate based implant coatings are discussed.
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http://dx.doi.org/10.1007/s10856-007-3064-zDOI Listing
August 2007

Titania and titania-silica coatings for titanium: comparison of ectopic bone formation within cell-seeded scaffolds.

Tissue Eng 2007 Apr;13(4):855-63

Department of Prosthetic Dentistry and Biomaterials Science, Institute of Dentistry, University of Turku, Turku, Finland.

The aim of this study was to compare titania (TiO(2))-coated, titania-silica (TiSi)-coated, and uncoated (cpTi) titanium fiber meshes as scaffolds for bone engineering. The scaffolds were loaded with bone marrow stromal cells and implanted subcutaneously in rats. Ectopic bone formation after 1, 4, and 12 weeks of implantation was evaluated using histology and histomorphometry. After 1 week of implantation, multiple patches of unorganized mineralizing tissue were seen in all implants. The amount of this bone-like tissue clearly increased from 1 to 4 weeks. Bone apposition occurred in direct contact with coated meshes, while a thin layer of unmineralized fibrous tissue was often observed surrounding cpTi mesh fibers. After 12 weeks, the structure of bone, with bone marrow-like tissue, was further matured and mesh fibers were embedded in lamellar bone. No statistical differences in the amount of mineralized bone were observed between scaffold types at any point of time. Only TiSi scaffolds showed further increase in bone area from 4 to 12 weeks (p < 0.01). A notable difference was that the sol-gel coatings resulted in enhanced initial bone contact and distribution of bone tissue, whereas uncoated implants showed bone formation mainly in the center of the scaffolds. In conclusion, TiO(2)-based sol-gel coatings may be used in tissue engineering to gain more uniform distribution of bone throughout titanium fiber mesh scaffolds.
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http://dx.doi.org/10.1089/ten.2006.0234DOI Listing
April 2007

Hydroxyapatite coating of cellulose sponge does not improve its osteogenic potency in rat bone.

Acta Biomater 2005 Sep 15;1(5):535-44. Epub 2005 Jul 15.

Department of Medical Biochemistry and Molecular Biology, University of Turku, Kiinamyllynkatu 10, FIN-20520 Turku, Finland.

Regenerated cellulose sponges were coated biomimetically with hydroxyapatite to increase their osteogenic properties. Induction of apatite precipitation was carried out with bioactive glass in simulated body fluid (SBF) for 24 h and the final coating was carried out in 1.5 x concentrated SBF for 14 days. Biomimetically mineralized and non-mineralized sponges were then implanted into standard size femoral cortical defects of rats, and the invasion of bone into the implant was followed up to one year. The apatite coating did not improve the osteoconductive property of cellulose in this rat cortical defect model. In fact, it generated a strong and highly cellular inflammatory reaction and less osteoid tissue. The biomimetic implants contained more immunodetectable TGFbeta1 (a strong stimulator of fibroblast activity) than untreated implants, and also bound more TGFbeta1 in vitro, which could, at least in part, explain the fibrotic invasion of biomimetically mineralized sponges.
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http://dx.doi.org/10.1016/j.actbio.2005.05.003DOI Listing
September 2005