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Session: Poster session I
Session starts: Thursday 24 January, 15:00

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Bogdan Necula (Delft University of Technology)
Lidy Fratila-Apachitei (Delft University of Technology)
J.P.T.M. van Leeuwen (Erasmus Medical Center, Rotterdam)
S.A.J. Zaat (Academic Medical Center, Amsterdam)
Iulian Apachitei (Delft University of Technology)
Jurek Duszczyk (Delft University of Technology)

Abstract:
The most devastating complications encountered in total joint arthroplasty are implant-associated infections. Next to patient trauma, the treatment of these infections accounts for high healthcare costs. Therefore, implants that hold an antibacterial function to prevent bacteria colonization to the implant surface might be a suitable solution to this clinical problem. The aim of this study was to test the in vitro bone cell viability and antibacterial efficacy of Ag-bearing oxidized surfaces prepared by Plasma Electrolytic Oxidation (PEO) process on the medical grade Ti6Al7Nb alloy. The oxidized surfaces were produced in electrolytes containing calcium acetate/calcium glycerophosphate salts and two different concentrations of Ag nano-sized particles (0.3 and 3.0 g/L) as bactericidal agent. The morphology of the oxidized surfaces was investigated by Scanning Electron Microscopy. Simian Virus Human Fetal Osteoblast (SV-HFO) cells viability was quantitatively determined using the Alamar Blue assay after 2, 5 and 7 days of culture. The in vitro antibacterial activity of the TiO2-Ag surfaces against methicillin-resistant Staphylococcus aureus (MRSA) was assessed using the direct contact assay, specifically developed to mimic the conditions of an infection of a primary total joint replacement [1]. The surfaces produced by PEO revealed a porous structure consisting of both amorphous and crystalline TiO2 phases. Ag nanoparticles were found both on the surface and inside of the pores. In vitro viability tests showed SV-HFO cells proliferation after 2, 5 and 7 days on TiO2-0.3Ag and TiO2 (Ag-free) surfaces without notable differences between them. However, the TiO2-3Ag surfaces inhibited cell proliferation at all time-points. In vitro antibacterial testing proved excellent MRSA killing rates after 24 hours for both TiO2-0.3Ag and TiO2-3Ag samples with efficiencies of 98.25% and >99.75%, respectively. On the TiO2 control surface the number of CFU increased 1000-fold. From the two different surfaces tested, the one produced with low concentration of Ag nanoparticles showed both bone cell viability and bactericidal activity. The findings suggest that the PEO process may be an appropriate surface modification technology for bone implants allowing synthesis of cytocompatible TiO2 surfaces with antibacterial function. REFERENCES [1] B.S. Necula, L.E. Fratila-Apachitei, S.A.J. Zaat, I. Apachitei, J. Duszczyk, “In vitro antibacterial activity of porous TiO2-Ag composite layers against methicillin-resistant Staphylococcus aureus”, Acta Biomater., Vol. 5, pp. 3573−3580, (2009).