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| 5. |
- 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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| 6. |
- 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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| 7. |
- 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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| 8. |
- 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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| 9. |
- 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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| 11. |
- 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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| 12. |
- Sörensen, Jan Henrik, et al.
(författare)
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Biomechanical and Antibacterial Properties of Tobramycin Loaded Hydroxyapatite Coated Fixation Pins
- 2014
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Ingår i: Journal of Biomedical Materials Research. Part B - Applied biomaterials. - : Wiley. - 1552-4973 .- 1552-4981. ; 102:7, s. 1381-1392
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Tidskriftsartikel (refereegranskat)abstract
- The present study investigates the use of nanoporous, biomimetic hydroxyapatite (HA) coatings deposited on TiO2 coated fixation pins as functional implant surfaces for the local release of Tobramycin in order to prevent bacterial colonization. The impact of HA-coating thickness, coating morphology and biomechanical forces during insertion into synthetic bone on the drug loading and release properties are analyzed. The coatings are shown to exhibit bactericidal effects against Staphylococcus aureus in agar medium for a duration of 6 days after loading by adsorption with Tobramycin for only 5 min at elevated temperature and pressure. Furthermore, high performance liquid chromatography analysis shows a drug release in phosphate buffered saline for 8 days with antibiotic concentration remaining above the minimal inhibitory concentration for S. aureus during the entire release period. Biomechanical insertion tests into synthetic bone and conventional scratch testing demonstrate adhesive strength at the HA/TiO2 interface. Biocompatibility is verified by cell viability tests. Outgrowth endothelial cells, as well as primary osteoblasts, are viable and firmly attached to both HA and TiO2 surfaces. The results presented are encouraging and support the concept of functional HA coatings as local drug delivery vehicles for biomedical applications to treat as well as to prevent post-surgical infections.
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| 13. |
- Sörensen, Jan H, et al.
(författare)
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Co-precipitation of Tobramycin into Biomimetically Coated Orthopedic Fixation Pins Employing Submicron-Thin Seed Layers of Hydroxyapatite
- 2014
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Ingår i: Current Drug Delivery. - : Bentham Science Publishers Ltd.. - 1567-2018 .- 1875-5704. ; 11:4, s. 501-510
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Tidskriftsartikel (refereegranskat)abstract
- Implant migration, loosening and cut-out as well as nosocomial infections are current problems during surgery. New innovative strategies to overcome these issues are emphasized in today's research. The currentwork presents a novel strategy involving co-precipitation ofTobramycin with biomimetic hydroxyapatite (HA) formation to produce implant coatings that may ensure controlled local drug delivery to prevent early bacterial colonization of the implant. A sub-micron thin HA layer served as seed layer for the co-precipitation process and allowed for incorporation of Tobramycin in the coating from a stock solution of antibiotic concentrations as high as 20 mg/ml. Concentrations from 0.5 to 20 mg/ml Tobramycin and process temperatures of 37 °C and 60 °C were tested to assess the optimal parameters resulting in a thin Tobramycin delivering HA coating on discs and orthopedic fixation pins. The coating morphology and thickness as well as drugrelease profile were evaluated via scanning electron microscopy and high performanceliquid chromatography. The coatings were found to deliver pharmaceutically relevant amounts of Tobramycinover a period as of12 days. To the best of our knowledge, this is the longest release period ever observed for a fast-loaded biomimetic implant coating. The presented approach may form thefoundation for development of combination device/antibiotic delivery vehicles tailored to meet well-defined clinical needs combatting infections and ensuring fast implant in-growth.
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| 15. |
- Welch, Ken, et al.
(författare)
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Bioactive and photocatalytically active surgical implant surfaces
- 2012
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Ingår i: Euro Bio-inspired Materials, International School and Conference on Biological Materials Science, 20-23 March.
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Konferensbidrag (refereegranskat)abstract
- Improving biomedical implants via deposition of functionalised surface coatings is a growing field of research. An enhanced bone-bonding capability by induction of hydroxyapatite (HA) formation on the implant surface is a critical characteristic of a bioactive implant coating. In the field of implants, infections present a major problem, and result mostly from the contamination of the implant surface by bacteria during surgery. There is a need for antibacterial surface treatments, which can prevent the bacterial colonization and biofilm formation without compromising the biocompatibility of the implant itself.Crystalline TiO2 is not only a bioactive, non-resorbable material, it also exhibits excellent superhydrophilic and photocatalytic properties when irradiated with UV light. Thus, UV irradiation induced photocatalysis on crystalline TiO2 implant surfaces may present an effective method for decontaminating implant surfaces.In our study we have evaluated the influence of the main deposition parameters in the cathodic evaporation process on the microstructure of TiO2 thin films and correlated 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 HA after 7 days in phosphate buffered saline at 37 °C. Comparison of the HA growth after 24 hours indicated enhanced HA formation on coatings with small titanium dioxide grains of the rutile and the 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 to 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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| 17. |
- Aurell, Emelie, et al.
(författare)
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Mikroplaster : Redovisning av regeringsuppdrag om källor till mikroplaster och förslag på åtgärder för minskade utsläpp i Sverige
- 2017
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- I augusti 2015 fick Naturvårdsverket i uppdrag från regeringen att identifiera viktigare källor i Sverige till utsläpp av mikroplaster till havet och verka för att reducera utsläppen från dessa källor. I den här rapporten redovisar Naturvårdsverket uppdraget. Vi presenterar resultaten från den första, övergripande kartläggningen av källor till och spridning av mikroplaster i Sverige, en bedömning av vilka av de kartlagda källorna som primärt bör åtgärdas samt vilka steg som behöver tas för att förebygga utsläpp och minska spridning av mikroplaster till hav, sjöar och vattendrag från dessa källor.Förekomsten av mikroplast i den marina miljön har uppmärksammats allt mer under senare år, inte minst på global nivå. Mikroplast är ett samlingsnamn för små, små plastfragment (1 nm till 5 mm). De mikroplaster som hittats i världshaven, men även i sötvattensystem, har olika ursprung. Mikroplast kan bildas oavsiktligt när plastföremål slits och plastpartiklar frigörs, eller när vi inte återanvänder, återvinner eller slänger plastmaterial på rätt sätt utan plasten blir skräp som succesivt bryts ned till mindre och mindre bitar i naturen. Det finns också plast som från början tillverkas som små pellets eller korn.Utgångspunkten för arbetet har varit miljökvalitetsmålen Hav i balans samt levande kust och Levande sjöar och vattendrag samt målet om Giftfri miljö. Reduceradeutsläpp av mikroplaster till hav, sjöar och vattendrag bidrar till att nå dessa mål.Uppdraget har genomförts av Naturvårdsverket i samarbete med Havs- och vattenmyndigheten, andra berörda myndigheter, samt med deltagande av berörda organisationer och andra intressenter mellan augusti 2015 och maj 2017. Slutsatserna är Naturvårdsverkets egna.
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| 19. |
- Ballo, Ahmed, 1978, et al.
(författare)
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Bone response to physical-vapour-deposited titanium dioxide coatings on titanium implants
- 2013
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Ingår i: Clinical Oral Implants Research. - : Wiley. - 0905-7161 .- 1600-0501. ; 24:9, s. 1009-1017
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Tidskriftsartikel (refereegranskat)abstract
- Objectives: The aim of this study was to investigate the correlation between coating thickness and the crystal structure of physical-vapour-deposited (PVD) titanium dioxide coatings, and to evaluate their in vivo biocompatibility. Materials and methods: The PVD TiO 2 coatings of different thickness were deposited on machined titanium grade 2 screw-shaped implants. Non-coated titanium implants were used as controls. Coating properties such as thickness, crystal structure, coating morphology and roughness were characterized. Forty-eight implants were placed randomly into both tibias of 16 rats. The animals were euthanized 7 and 28 days postsurgery and block biopsies were prepared for histology, histomorphometry and SEM analysis. Results: The thicknesses of the PVDTiO 2 coatings were 120 and 1430 nm respectively. Histologically, new bone formed on all implant surfaces. The mean percentage of newly formed bone in contact with the implant (BIC) was significantly higher at early healing time (7 days) for the 120 nm thick PVD coating (39 ± 14%) than for both the 1430 nm thick PVD coating (22 ± 10%) (P = 0.043) and the machined surface (22 ± 9%) (P = 0.028). This difference was no longer evident after 28 days (P = 0.867). Conclusion: Bone formation and bone-to-implant contact are achieved to the same degree for TiO 2 surface modifications prepared by a PVD process as clinically used, machined titanium. Furthermore, a relatively thinner PVD coating promotes a higher degree of bone apposition shortly after implantation, thereby providing rationales for exploring the potential clinical use of these modifications.
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| 20. |
- Baruth, Joshua M., et al.
(författare)
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Distal radius fractures and risk of incident neurocognitive disorders in older adults : a retrospective cohort study
- 2022
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Ingår i: Osteoporosis International. - : Springer Science and Business Media LLC. - 0937-941X .- 1433-2965. ; 33:11, s. 2307-2314
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Tidskriftsartikel (refereegranskat)abstract
- Introduction: Distal radius fractures (DRF) are associated with increased risk of subsequent fractures and physical decline in older adults. This study aims to evaluate the risk cognitive decline following DRF and potential for timely screening and intervention. Methods: A cohort of 1046 individuals 50–75 years of age with DRF were identified between 1995 and 2015 (81.5% female; mean age 62.5 [± 7.1] years). A control group (N = 1044) without history of DRF was matched by age, sex, and fracture date (i.e., index). The incidence of neurocognitive disorders (NCD) in relation to DRF/index was determined. Group comparisons were adjusted by age and comorbidity measured by the Elixhauser index. Results: The DRF group had a greater incidence of NCD compared to the control group (11.3% vs. 8.2%) with a 56% greater relative risk (HR = 1.56, 95% Cl: 1.18, 2.07; p = 0.002) after adjusting for age and comorbidity. For every 10-year age increase, the DRF group was over three times more likely to develop a NCD (HR = 3.23, 95% Cl: 2.57, 4.04; p < 0.001). Conclusion: DRF in adults ages 50 to 75 are associated with increased risk of developing neurocognitive disorders. DRF may represent a sentinel opportunity for cognitive screening and early intervention. Summary: Distal radius fractures (DRF) have been associated with greater risk of future fractures and physical decline. This study reports that DRF are also associated with greater risk of developing neurocognitive disorders in older adults. Timely intervention may improve early recognition and long-term outcomes for older adults at risk of cognitive decline.
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| 22. |
- Nilsson, Daniel, 1974-
(författare)
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Synthesis and Evaluation of TaC:C Low-Friction Coatings
- 2004
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In the large family of carbon-based coatings there are members capable of providing a rare and very desirable combination of high wear resistance and low friction. The field of application for this kind of coatings is steadily increasing which, naturally, give raise to new questions and demands.Coatings of this type can be produced in a number of different ways, but the parameter influencing their properties most is the chemical composition. To facilitate investigations of the compositional impact on the synthesis and properties of coatings, a way to alloy magnetron-sputtered thin films was developed in this thesis. It does not involve the use of reactive gases or additional material sources; instead metallic foils are attached onto the magnetron target surface and thus sputtered alongside the target material. This co-sputtering route was later used to synthesize carbon coatings alloyed with Ta, Zr, W and Al in various amounts and configurations.It was shown that the co-sputtering method could be used to alloy coatings in a very simple and straightforward manner, with excellent possibilities of controlling the amount of alloying elements. The process temperature could be kept as low as 70 °C.Carbon coatings alloyed with transition metals (MeC:C) displayed polycrystalline nanocomposite structures with 5 nm metal carbide crystallites in a matrix of near-amorphous carbon. Alloying with Ta resulted in a radical 80 % reduction in friction coefficient during dry sliding in air, from 0.22 for pure carbon to 0.04 for TaC:C. This was found to be due to facilitated graphitization and the formation of lubricating surface oxides. Al additions to TaC:C resulted in a transformation of the TaC phase to a metastable, previously unreported Ta1-χAlχC. The coefficient of friction remained unaltered, but the oxidation rate compared to TaC:C was significantly reduced due to the formation of AlTaO4 instead of Ta2O5.
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| 23. |
- Nilvebrant, Johan, et al.
(författare)
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Engineering of Bispecific Affinity Proteins with High Affinity for ERBB2 and Adaptable Binding to Albumin
- 2014
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Ingår i: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 9:8, s. e103094-
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Tidskriftsartikel (refereegranskat)abstract
- The epidermal growth factor receptor 2, ERBB2, is a well-validated target for cancer diagnostics and therapy. Recent studies suggest that the over-expression of this receptor in various cancers might also be exploited for antibody-based payload delivery, e. g. antibody drug conjugates. In such strategies, the full-length antibody format is probably not required for therapeutic effect and smaller tumor-specific affinity proteins might be an alternative. However, small proteins and peptides generally suffer from fast excretion through the kidneys, and thereby require frequent administration in order to maintain a therapeutic concentration. In an attempt aimed at combining ERBB2-targeting with antibody-like pharmacokinetic properties in a small protein format, we have engineered bispecific ERBB2-binding proteins that are based on a small albumin-binding domain. Phage display selection against ERBB2 was used for identification of a lead candidate, followed by affinity maturation using second-generation libraries. Cell surface display and flow-cytometric sorting allowed stringent selection of top candidates from pools pre-enriched by phage display. Several affinity-matured molecules were shown to bind human ERBB2 with sub-nanomolar affinity while retaining the interaction with human serum albumin. Moreover, parallel selections against ERBB2 in the presence of human serum albumin identified several amino acid substitutions that dramatically modulate the albumin affinity, which could provide a convenient means to control the pharmacokinetics. The new affinity proteins competed for ERBB2-binding with the monoclonal antibody trastuzumab and recognized the native receptor on a human cancer cell line. Hence, high affinity tumor targeting and tunable albumin binding were combined in one small adaptable protein.
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| 24. |
- Persson, Maria, et al.
(författare)
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Classification of crops and weeds extracted by active shape models
- 2008
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Ingår i: Biosystems Engineering. - New York : Elsevier. - 1537-5110 .- 1537-5129. ; 100:4, s. 484-497
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Tidskriftsartikel (refereegranskat)abstract
- Active shape models (ASMs) for the extraction and classification of crops using real field images were investigated. Three sets of images of crop rows with sugar beet plants around the first true leaf stage were used. The data sets contained 276, 322 and 534 samples, equally distributed over crops and weeds. The weed populations varied between the data sets resulting in from 19% to 53% of occluded crops. Three ASMs were constructed using different training images and different description levels. The models managed to correctly extract up to 83% of the crop pixels and remove up to 83% of the occluding weed pixels. Classification features were calculated from the shapes of extracted crops and weeds and presented to a k-NN classifier. The classification results for the ASM-extracted plants were compared to classification results for manually extracted plants. It was judged that 81–87% of all plants extracted by ASM were classified correctly. This corresponded with 85–92% for manually extracted plants.
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| 25. |
- Åstrand, Björn, 1969-, et al.
(författare)
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Segmentation of partially occluded plant leaves
- 2006
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Ingår i: IWSSIP 200613th International Conference on Systems, Signals and Image ProcessingSeptember 21-23, 2006, Budapest, Hungary. - Stockholm : Harlequin. - 8089082092
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Konferensbidrag (refereegranskat)abstract
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