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- Lilja, Mirjam, 1981-, et al.
(författare)
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Drug loading and release of Tobramycin from Hydroxyapatite coated fixation pins
- 2013
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Ingår i: Journal of materials science. Materials in medicine. - : Springer Science and Business Media LLC. - 0957-4530 .- 1573-4838. ; 24:9, s. 2265-2274
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Tidskriftsartikel (refereegranskat)abstract
- This paper evaluates the loading and release properties of Tobramycin incorporated by adsorptive loading from a solution into plasma sprayed and biomimetically coated Hydroxyapatite (HA) fixation pins. The aim of this study is to contribute towards designing a functional implant surface offering local release of the antibiotic agent to prevent post-surgical infections. Cathodic arc deposition is used to coat stainless steel fixation pins with a bioactive, anatase phase dominated, TiO2 coating onto which a HA layer is grown biomimetically. The loading and release properties are evaluated by studying the subsequent release of Tobramycin using high performance liquid chromatography and correlated to the differences in HA coating microstructure and the physical conditions under loading. The results from these studies show that a dual loading strategy consisting of a solution temperature of 90 °C and a pressure of 6 bar during a loading time of 5 min release a sufficient amount of Tobramycin to guarantee the inhibition of Staphylococcus aureus up to 2 days for plasma sprayed HA coatings and for 8 days for biomimetic coatings. The present study emphasizes the advantages of the nanoporous structure of biomimetically deposited HA over the more dense structure of plasma sprayed HA coatings in terms of antibiotic incorporation and subsequent sustained release and provides a valuable outline for the design of implant surfaces aiming for a fast-loading and controlled, local drug administration.
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- Lilja, Mirjam, et al.
(författare)
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Effect of deposition parameters on the photocatalytic activity and bioactivity of TiO(2) thin films deposited by vacuum arc on Ti-6Al-4V substrates
- 2012
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Ingår i: Journal of Biomedical Materials Research. Part B - Applied biomaterials. - : Wiley. - 1552-4973 .- 1552-4981. ; 100B:4, s. 1078-1085
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Tidskriftsartikel (refereegranskat)abstract
- This article evaluates the influence of the main parameters in a cathodic arc deposition process on the microstructure of titanium dioxide thin coatings and correlates these to the photocatalytic activity (PCA) and in vitro bioactivity of the coatings. Bioactivity of all as deposited coatings was confirmed by the growth of uniform layers of hydroxyapatite (HA) after 7 days in phosphate buffered saline at 37°C. Comparison of the HA growth after 24 h indicated enhanced HA formation on coatings with small titanium dioxide grains of rutile and anatase phase. The results from the PCA studies showed that coatings containing a mixed microstructure of both anatase and rutile phases, with small grain sizes in the range of 26-30 nm and with a coating thickness of about 250 nm, exhibited enhanced activity as compared with other microstructures and higher coating thickness. The results of this study should be valuable for the development of new bioactive implant coatings with photocatalytically induced on-demand antibacterial properties.
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- Lilja, Mirjam, 1981-, et al.
(författare)
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Impact of Biomechanical Forces on Antibiotics Release Kinetics from Hydroxyapatite Coated Surgical Fixation Pins
- 2013
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Ingår i: Journal of Biomaterials and Nanobiotechnology. - : Scientific Research Publishing, Inc.. - 2158-7027 .- 2158-7043. ; 4:4, s. 343-350
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Tidskriftsartikel (refereegranskat)abstract
- This work investigates the impact of biomechanical wear and abrasion on the antibiotic release profiles of hydroxyapa-tite (HA) coated fixation pins during their insertion into synthetic bone. Stainless steel fixation pins are coated with crystalline TiO2 by cathodic arc evaporation forming the bioactive layer for biomimetic deposition of Tobramycin con-taining HA. Tobramycin is either introduced by co-precipitation during HA formation or by adsorption-loading after HA deposition. The samples containing antibiotics are inserted into bone mimicking polyethylene foam after which the drug release is monitored using high performance liquid chromatography. This analysis shows that HA coating wear and delamination significantly decrease the amount of drug released during initial burst, but only marginally influence the sustained release period. Spalled coating fragments are found to remain within the synthetic bone material structure. The presence of HA within this structure supports the assumption that the local release of Tobramycin is not only ex-pected to eliminate bacteria growth directly at the pin interface but as well at some distance from the implant. Further-more, no negative effect of gamma sterilization could be observed on the drug release profile. Overall, the observed results demonstrate the feasibility of a multifunctional implant coating that is simultaneously able to locally deliver clinically relevant doses of antibiotics and an HA coating capable of promoting osteoconduction. This is a potentially promising step toward orthopaedic devices that combine good fixation with the ability to treat and prevent post-surgical infections.
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- Lilja, Mirjam, 1981-, et al.
(författare)
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Influence of microstructure and chemical composition of sputter deposited TiO2 thin films on in vitro bioactivity
- 2011
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Ingår i: Journal of materials science. Materials in medicine. - : Springer. - 0957-4530 .- 1573-4838. ; 22:12, s. 2727-2734
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Tidskriftsartikel (refereegranskat)abstract
- Functionalisation of biomedical implants viasurface modifications for tailored tissue response is agrowing field of research. Crystalline TiO2 has been provento be a bone bioactive, non-resorbable material. In contactwith body fluids a hydroxyapaptite (HA) layer forms on itssurface facilitating the bone contact. Thus, the path ofimproving biomedical implants via deposition of crystallineTiO2 on the surface is interesting to follow. In thisstudy we have evaluated the influence of microstructureand chemical composition of sputter deposited titaniumoxide thin films on the in vitro bioactivity. We find thatboth substrate bias, topography and the flow ratio of thegases used during sputtering affect the HA layer formed onthe films after immersion in simulated body fluid at 37C.A random distribution of anatase and rutile crystals, formedat negative substrate bias and low Ar to O2 gas flow ratios,are shown to favor the growth of flat HA crystal structureswhereas higher flow ratios and positive substrate biasinduced growth of more spherical HA structures. Thesefindings should provide valuable information when optimizingthe bioactivity of titanium oxide coatings as well asfor tailoring process parameters for sputtered-based productionof bioactive titanium oxide implant surfaces.
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- Lilja, Mirjam, 1981-, et al.
(författare)
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Photocatalytic and antimicrobial properties of surgical implant coatings of titanium dioxide deposited though cathodic arc evaporation
- 2012
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Ingår i: Biotechnology letters. - : Springer Science and Business Media LLC. - 0141-5492 .- 1573-6776. ; 41:6, s. 740-746
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Tidskriftsartikel (refereegranskat)abstract
- Nanostructured crystalline titaniumdioxide coatings deposited by cathodic arc evaporated on titanium grade five medical implant substrates were demonstrated to exhibit UV-induced photocatalytic activity that can be utilized to provide bactericidal effects against Staphylococcus epidermidis. The photocatalytic activity of the coatings was confirmedvia degradation of Rhodamine B under UV illumination.A 90 %reduction of viable bacteria was achieved in a clinically suitable time of only 2 min with a UVdose of 2.4 J delivered at 365 nm. These results areencouraging for the development of antimicrobialsurfaces in orthopedics and dentistry in order to prevent or treat post-surgical infections.
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- Lilja, Mirjam, 1981-, et al.
(författare)
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Photocatalytic and bioactive TiO2 thin films deposited by vacuum arc
- 2012
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Ingår i: European Cells & Materials. - Aberystwyth : University of Wales. - 1473-2262. ; 23:Suppl. 5, s. 48-
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Tidskriftsartikel (refereegranskat)abstract
- Improving biomedical implants via deposition of functionalised surface coatings is a growing field of research. With respect to implant surfaces, infections present a major problem, and result mostly from the contamination of the surface by bacteria during surgery. UV irradiation induced photocatalysis on crystalline TiO2 implant surfaces may present a promising way to decontaminate surfaces while at the same time providing a bioactive surface for enhanced tissue integration.
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