Eva Eisenbarth - Academia.edu (original) (raw)

Papers by Eva Eisenbarth

Revue de Stomatologie et de Chirurgie Maxillo-faciale

An in vitro study has been carried out in different cell systems to determine the biological resp... more An in vitro study has been carried out in different cell systems to determine the biological response of TiNb30 alloy before and after a surface treatment with hydroxyapatite (HA) and tricalcium phosphate (TCP) by the sol-gel method. TiNb30 pure Ti induce favorable cell viability with respect to pure Ni showing a high cytotoxic effect. After surface treatment with HA or HA-TCP mixtures, no difference in cell proliferation can be observed between amorphous and cristalline forms. However, HA decreases (75 +/- 15%) and HA-TCP mixtures increase (133 +/- 11%) significantly cell proliferation compared with controls.

Advances in biochemical engineering/biotechnology, 2009

Technical aspects play an important role in tissue engineering. Especially an improved design of ... more Technical aspects play an important role in tissue engineering. Especially an improved design of bioreactors is crucial for cultivation of artificial three-dimensional tissues in vitro. Here formation of cartilage-carrier-constructs is used to demonstrate that the quality of the tissue can be significantly improved by using optimized culture conditions (oxygen concentration, growth factor combination) as well as special bioreactor techniques to induce fluid-dynamic, hydrostatic or mechanical load during generation of cartilage.

Kirk-Othmer Encyclopedia of Chemical Technology, 2000

Fundamentals and Applications, 2003

... Ti and its alloys belong to the same group as stainless steel, while CoCr alloys, niobium, an... more ... Ti and its alloys belong to the same group as stainless steel, while CoCr alloys, niobium, and, especially, tantalum are more expensive. ... This is achieved by optimizing the sintering parameters, cold pressure, sintering tempera-ture and time, grain size PGF, thickness of the ...

Titan und Titanlegierungen, 2002

Metallic Biomaterial Interfaces, 2008

... Acknowledgments The authors are very thankful to the DOT GmbH Rostock for providing us with s... more ... Acknowledgments The authors are very thankful to the DOT GmbH Rostock for providing us with structured titanium. We acknowledge the technical help of Gerhard Fulda of the Electron Microscopic Centre of the Medical Faculty of the University of Rostock. ...

Surface and Interface Analysis, 2000

ABSTRACT

Surface and Interface Analysis, 2002

The excellent biocompatibility of titanium and its alloys is associated with the properties of th... more The excellent biocompatibility of titanium and its alloys is associated with the properties of their dense TiO 2 layer on the surface. The adsorption of proteins of the body fluid to implant surfaces depends on the properties of the surface oxide layer, especially the electronic structure. Therefore, tailoring of the oxide layer is a method for influencing protein adsorption. In this study, titanium platelets are coated by the sol-gel process with mixed oxides containing the biocompatible elements Ti, Nb, Zr and Ta. In order to verify the composition of the produced oxide layer, which can differ from the adjusted precursor composition in the sol because of different reactivities of the precursors, the layers were analysed with x-ray photoelectron spectroscopy by carrying out sputter profiles. It was proved that the composition of a mixed-oxide layer prepared by the sol-gel process can be tailored by the use of mixed precursors.

Biomolecular Engineering, 2007

Biomaterials and tissue engineering technologies are becoming increasingly important in biomedica... more Biomaterials and tissue engineering technologies are becoming increasingly important in biomedical practice, particularly as the population ages. Cellular responses depend on topographical properties of the biomaterial at the nanometer scale. Structures on biomaterial surfaces are used as powerful tools to influence or even control interactions between implants and the biological system [

Biomolecular Engineering, 2002

The interaction between cells and implant materials is determined by the surface structure and/or... more The interaction between cells and implant materials is determined by the surface structure and/or surface composition of the material. In the past years, titanium and titanium alloys have proved their superiority over other implant materials in many clinical applications. This predominant behaviour is caused by a dense passive oxide layer which forms within milliseconds in oxidizing media. Titanium dioxide layers of 100 nm thickness were produced on the surface of cp-titanium grade 2, and on an experimental alloy of high vanadium content (Ti1.5Al25V) as a harmful control. The layers were produced by thermal and anodic oxidation and by coating by means of the sol Á/gel process. The resulting oxide layers were characterized with respect of their structure and chemical composition. In cell tests (proliferation, MTT, morphology, actin staining), the reaction of the cells was examined. It was shown that the sol Á/gel-produced titanium oxide layer is able to shield the cells from toxic alloying elements, with the result that the cell reaction is influenced only by the thin titanium oxide surface layer and not by the composition of the bulk material.

Biomolecular Engineering, 2002

A stable connection between the biomaterial surface and the surrounding tissue is one of the most... more A stable connection between the biomaterial surface and the surrounding tissue is one of the most important prerequisites for the long-term success of implants. Therefore, a strong adhesion of the cells on the biomaterial surface is required. Beside the surface composition the surface topography influences the properties of the adherent cells. The quality of the connection between the cell and the biomaterial is-among other factors-determined by the dimensions of the surface topography. Osteoblasts and fibroblast-like cells in contact with a ground biomaterial surface spread in the direction of the surface structures. These aligned cells provide a more favourable adhesion behaviour than a spherically shaped cell. To determine the influence of the surface structure on the cell alignment and cytoskeleton organisation or arrangement, substrate discs of cp-titanium were ground, producing different roughness of the substrates.The oriented cells had a higher density of focal contacts when they were in contact with the edges of the grooves and showed a better organisation of the cytoskeleton and stronger actin fibres. These changes of the aligned cells depend on the peak to valley height of the surface structures.

Journal of Materials Science: Materials in Medicine, 2008

Endothelial cells cover the inner surface of blood vessels and form the interface between the blo... more Endothelial cells cover the inner surface of blood vessels and form the interface between the blood and the tissues. Endothelial cells are involved in regulating barrier function, which is maintained by the interendothelial cell contacts. These interendothelial cell contacts are established by the interaction of different molecules. The maintenance of the barrier requires an appropriate signalling between these molecules. Thus, a number of different signalling pathways are integrated within interendothelial contacts. Since endothelial cells are important in tissue-implant interactions (especially for stent materials) this study examines the expression pattern of different interendothelial contact molecules to determine the usefulness in the analysis of biocompatibility in vitro. The effects of different pro-inflammatory and toxic stimuli and contact of human microvascular endothelial cells to metallic surfaces were examined for their impact on the pattern of interendothelial contact molecules. Striking modifications in the arrangement of these molecules were induced and the mode of modification was dependent on the tested compound. Thus, examining the pattern of expression of specific interendothelial contact molecules in vitro may be useful for testing the endothelial cell compatibility of biomaterials and their corrosion products.

Journal of Materials Science: Materials in Medicine, 2000

Thin biocompatible oxide ®lms with an optimised composition and structure on the surface of titan... more Thin biocompatible oxide ®lms with an optimised composition and structure on the surface of titanium and its alloys can improve the implant integration. The preparation of these thin oxide layers with the intended improvement of the surface properties can be realised by means of the sol±gel process. Nb 2 O 5 is a promising coating material for this application because of its extremely high corrosion resistance and thermodynamic stability. In this study, thin Nb 2 O 5 layers (5 200 nm) were prepared by spin coating of polished discs of cptitanium with a sol consisting of a mixture of niobium ethoxide, butanol and acetylacetone. The thickness, phase composition, corrosion resistance and the wettability of the oxide layers were determined after an optimisation of the processing parameters for deposition of oxide without any organic impurities. The purity of the oxide layer is an important aspect in order to avoid a negative response to the cell adhesion. The biocompatibility of the oxide layers which was investigated by in vitro tests (morphology, proliferation rate, WST-1, cell spreading) is improved as compared to uncoated and TiO 2 sol±gel coated cp-titanium concerning the spreading of cells, collagen I synthesis and wettability.

Journal of Biomedical Materials Research Part A, 2006

The interaction of osteoblasts was correlated to the roughness of nanosized surface structures of... more The interaction of osteoblasts was correlated to the roughness of nanosized surface structures of Nb 2 O 5 coatings on polished CP titanium grade 2. Nb 2 O 5 sol-gel coatings were selected as a model surface to study the interaction of osteoblasts with nanosized surface structures. The surface roughness was quantified by determination of the average surface finish (Ra number) by means of atomic force microscopy. Surface topographies with Ra ¼ 7, 15, and 40 nm were adjusted by means of the annealing process parameters (time and temperature) within a solgel coating procedure. The observed osteoblast migration was fastest on smooth surfaces with Ra ¼ 7 nm. The adhesion strength, spreading area, and collagen-I synthesis showed the best results on an intermediate roughness of Ra ¼ 15 nm. The surface roughness of Ra ¼ 40 nm was rather peaked and reduced the speed of cell reactions belonging to the adhesion process.

Journal of Biomechanics, 2008

The dynamic friction coefficients of the commercial aluminum alloys (A2014, A2024 and A6061) and ... more The dynamic friction coefficients of the commercial aluminum alloys (A2014, A2024 and A6061) and a superplastic IN9021 alloy were measured by ring-compression tests in a temperature range from 573 to 753K and a stain rate range from 1.0 × 10 −2 to 4.0 × 10 0 s −1. In general the friction coefficients (m values) increase slightly with increasing the compressive strains even under the well-lubricated test conditions. The m values of the Al-Cu based alloys, including A2014, A2024 and IN9021, were almost same at 0.2~0.4 at the temperatures below 723K, but increased rapidly at the temperatures above 723K. On the other hand those of A6061 were almost constant at about 0.4 at the temperatures below 753K. The analysis based on the constitutive equation with consideration of the effect from an existence of the particles indicated that the dominant deformation mechanisms under the investigated conditions were dislocation creep for A2014, and were superplasticity for IN9021 except for the test condition at 573K with 1.0 × 10 −1 s −1. The m values of the IN9021 were lower than those of A2014, even if the flow stresses of IN9021 were higher than those of A2014. So it was concluded that the m value under a superplasticity region was lower than that under a dislocation creep region. It suggested that the superplastic forming had more benefits for the engineering applications.

Journal of Biomechanics, 2006

Journal of Biomechanics, 2006

Biomedizinische Technik/Biomedical Engineering, 2000

Biomedizinische Technik/Biomedical Engineering, 2000

Alloys based on titanium or cobalt have been used as implant materials for decades with good succ... more Alloys based on titanium or cobalt have been used as implant materials for decades with good success. Because of their natural oxide layer these alloys reveal good corrosion behaviour. In contact with physiological solution metal release takes place, which can cause inflammation. Coatings can improve the corrosion behaviour. In this study Ti6Al4V and Co28Cr6Mo alloys, which are frequently used as implant materials, were tested. Polished discs of these alloys and polished discs, which were coated with TiO2-layers by sol-gel chemistry, were compared regarding their corrosion behaviour and metal ion releasing. The releasing of Al, V, Ti, Co, Cr and Mo was quantified by ICP-MS analysis. The TiO2-coating reduced the release of all ions except of the Al-ion. Both alloys showed a deviating kinetic of ion releasing. In addition, cell response (cell vitality, cell proliferation, endothelial marker CD31 and actin allocation) of osteoblasts and endothelial cells were investigated.

Biomaterials, 2004

In comparison to the presently used alpha + beta titanium alloys for biomedical applications, bet... more In comparison to the presently used alpha + beta titanium alloys for biomedical applications, beta-titanium alloys have many advantageous mechanical properties, such as an improved wear resistance, a high elasticity and an excellent cold and hot formability. This will promote their future increased application as materials for orthopaedic joint replacements. Not all elements with beta-stabilizing properties in titanium alloys are suitable for biomaterial applications-corrosion and wear processes cause a release of these alloying elements to the surrounding tissue. In this investigation, the biocompability of alloying elements for beta- and near beta-titanium alloys was tested in order to estimate their suitability for biomaterial components. Titanium (grade 2) and the implant steel X2CrNiMo18153 (AISI 316 L) were tested as reference materials. The investigation included the corrosion properties of the elements, proliferation, mitochondrial activity, cell morphology and the size of MC3T3-E1 cells and GM7373 cells after 7 days incubation in direct contact with polished slices of the metals. The statistical significance was considered by Weir-test and Lord-test (alpha = 0.05). The biocompatibility range of the investigated metals is (decreasing biocompatibility): niobium-tantalum, titanium, zirconium-aluminium-316 L-molybdenum.

Revue de Stomatologie et de Chirurgie Maxillo-faciale

An in vitro study has been carried out in different cell systems to determine the biological resp... more An in vitro study has been carried out in different cell systems to determine the biological response of TiNb30 alloy before and after a surface treatment with hydroxyapatite (HA) and tricalcium phosphate (TCP) by the sol-gel method. TiNb30 pure Ti induce favorable cell viability with respect to pure Ni showing a high cytotoxic effect. After surface treatment with HA or HA-TCP mixtures, no difference in cell proliferation can be observed between amorphous and cristalline forms. However, HA decreases (75 +/- 15%) and HA-TCP mixtures increase (133 +/- 11%) significantly cell proliferation compared with controls.

Advances in biochemical engineering/biotechnology, 2009

Technical aspects play an important role in tissue engineering. Especially an improved design of ... more Technical aspects play an important role in tissue engineering. Especially an improved design of bioreactors is crucial for cultivation of artificial three-dimensional tissues in vitro. Here formation of cartilage-carrier-constructs is used to demonstrate that the quality of the tissue can be significantly improved by using optimized culture conditions (oxygen concentration, growth factor combination) as well as special bioreactor techniques to induce fluid-dynamic, hydrostatic or mechanical load during generation of cartilage.

Kirk-Othmer Encyclopedia of Chemical Technology, 2000

Fundamentals and Applications, 2003

... Ti and its alloys belong to the same group as stainless steel, while CoCr alloys, niobium, an... more ... Ti and its alloys belong to the same group as stainless steel, while CoCr alloys, niobium, and, especially, tantalum are more expensive. ... This is achieved by optimizing the sintering parameters, cold pressure, sintering tempera-ture and time, grain size PGF, thickness of the ...

Titan und Titanlegierungen, 2002

Metallic Biomaterial Interfaces, 2008

... Acknowledgments The authors are very thankful to the DOT GmbH Rostock for providing us with s... more ... Acknowledgments The authors are very thankful to the DOT GmbH Rostock for providing us with structured titanium. We acknowledge the technical help of Gerhard Fulda of the Electron Microscopic Centre of the Medical Faculty of the University of Rostock. ...

Surface and Interface Analysis, 2000

ABSTRACT

Surface and Interface Analysis, 2002

The excellent biocompatibility of titanium and its alloys is associated with the properties of th... more The excellent biocompatibility of titanium and its alloys is associated with the properties of their dense TiO 2 layer on the surface. The adsorption of proteins of the body fluid to implant surfaces depends on the properties of the surface oxide layer, especially the electronic structure. Therefore, tailoring of the oxide layer is a method for influencing protein adsorption. In this study, titanium platelets are coated by the sol-gel process with mixed oxides containing the biocompatible elements Ti, Nb, Zr and Ta. In order to verify the composition of the produced oxide layer, which can differ from the adjusted precursor composition in the sol because of different reactivities of the precursors, the layers were analysed with x-ray photoelectron spectroscopy by carrying out sputter profiles. It was proved that the composition of a mixed-oxide layer prepared by the sol-gel process can be tailored by the use of mixed precursors.

Biomolecular Engineering, 2007

Biomaterials and tissue engineering technologies are becoming increasingly important in biomedica... more Biomaterials and tissue engineering technologies are becoming increasingly important in biomedical practice, particularly as the population ages. Cellular responses depend on topographical properties of the biomaterial at the nanometer scale. Structures on biomaterial surfaces are used as powerful tools to influence or even control interactions between implants and the biological system [

Biomolecular Engineering, 2002

The interaction between cells and implant materials is determined by the surface structure and/or... more The interaction between cells and implant materials is determined by the surface structure and/or surface composition of the material. In the past years, titanium and titanium alloys have proved their superiority over other implant materials in many clinical applications. This predominant behaviour is caused by a dense passive oxide layer which forms within milliseconds in oxidizing media. Titanium dioxide layers of 100 nm thickness were produced on the surface of cp-titanium grade 2, and on an experimental alloy of high vanadium content (Ti1.5Al25V) as a harmful control. The layers were produced by thermal and anodic oxidation and by coating by means of the sol Á/gel process. The resulting oxide layers were characterized with respect of their structure and chemical composition. In cell tests (proliferation, MTT, morphology, actin staining), the reaction of the cells was examined. It was shown that the sol Á/gel-produced titanium oxide layer is able to shield the cells from toxic alloying elements, with the result that the cell reaction is influenced only by the thin titanium oxide surface layer and not by the composition of the bulk material.

Biomolecular Engineering, 2002

A stable connection between the biomaterial surface and the surrounding tissue is one of the most... more A stable connection between the biomaterial surface and the surrounding tissue is one of the most important prerequisites for the long-term success of implants. Therefore, a strong adhesion of the cells on the biomaterial surface is required. Beside the surface composition the surface topography influences the properties of the adherent cells. The quality of the connection between the cell and the biomaterial is-among other factors-determined by the dimensions of the surface topography. Osteoblasts and fibroblast-like cells in contact with a ground biomaterial surface spread in the direction of the surface structures. These aligned cells provide a more favourable adhesion behaviour than a spherically shaped cell. To determine the influence of the surface structure on the cell alignment and cytoskeleton organisation or arrangement, substrate discs of cp-titanium were ground, producing different roughness of the substrates.The oriented cells had a higher density of focal contacts when they were in contact with the edges of the grooves and showed a better organisation of the cytoskeleton and stronger actin fibres. These changes of the aligned cells depend on the peak to valley height of the surface structures.

Journal of Materials Science: Materials in Medicine, 2008

Endothelial cells cover the inner surface of blood vessels and form the interface between the blo... more Endothelial cells cover the inner surface of blood vessels and form the interface between the blood and the tissues. Endothelial cells are involved in regulating barrier function, which is maintained by the interendothelial cell contacts. These interendothelial cell contacts are established by the interaction of different molecules. The maintenance of the barrier requires an appropriate signalling between these molecules. Thus, a number of different signalling pathways are integrated within interendothelial contacts. Since endothelial cells are important in tissue-implant interactions (especially for stent materials) this study examines the expression pattern of different interendothelial contact molecules to determine the usefulness in the analysis of biocompatibility in vitro. The effects of different pro-inflammatory and toxic stimuli and contact of human microvascular endothelial cells to metallic surfaces were examined for their impact on the pattern of interendothelial contact molecules. Striking modifications in the arrangement of these molecules were induced and the mode of modification was dependent on the tested compound. Thus, examining the pattern of expression of specific interendothelial contact molecules in vitro may be useful for testing the endothelial cell compatibility of biomaterials and their corrosion products.

Journal of Materials Science: Materials in Medicine, 2000

Thin biocompatible oxide ®lms with an optimised composition and structure on the surface of titan... more Thin biocompatible oxide ®lms with an optimised composition and structure on the surface of titanium and its alloys can improve the implant integration. The preparation of these thin oxide layers with the intended improvement of the surface properties can be realised by means of the sol±gel process. Nb 2 O 5 is a promising coating material for this application because of its extremely high corrosion resistance and thermodynamic stability. In this study, thin Nb 2 O 5 layers (5 200 nm) were prepared by spin coating of polished discs of cptitanium with a sol consisting of a mixture of niobium ethoxide, butanol and acetylacetone. The thickness, phase composition, corrosion resistance and the wettability of the oxide layers were determined after an optimisation of the processing parameters for deposition of oxide without any organic impurities. The purity of the oxide layer is an important aspect in order to avoid a negative response to the cell adhesion. The biocompatibility of the oxide layers which was investigated by in vitro tests (morphology, proliferation rate, WST-1, cell spreading) is improved as compared to uncoated and TiO 2 sol±gel coated cp-titanium concerning the spreading of cells, collagen I synthesis and wettability.

Journal of Biomedical Materials Research Part A, 2006

The interaction of osteoblasts was correlated to the roughness of nanosized surface structures of... more The interaction of osteoblasts was correlated to the roughness of nanosized surface structures of Nb 2 O 5 coatings on polished CP titanium grade 2. Nb 2 O 5 sol-gel coatings were selected as a model surface to study the interaction of osteoblasts with nanosized surface structures. The surface roughness was quantified by determination of the average surface finish (Ra number) by means of atomic force microscopy. Surface topographies with Ra ¼ 7, 15, and 40 nm were adjusted by means of the annealing process parameters (time and temperature) within a solgel coating procedure. The observed osteoblast migration was fastest on smooth surfaces with Ra ¼ 7 nm. The adhesion strength, spreading area, and collagen-I synthesis showed the best results on an intermediate roughness of Ra ¼ 15 nm. The surface roughness of Ra ¼ 40 nm was rather peaked and reduced the speed of cell reactions belonging to the adhesion process.

Journal of Biomechanics, 2008

The dynamic friction coefficients of the commercial aluminum alloys (A2014, A2024 and A6061) and ... more The dynamic friction coefficients of the commercial aluminum alloys (A2014, A2024 and A6061) and a superplastic IN9021 alloy were measured by ring-compression tests in a temperature range from 573 to 753K and a stain rate range from 1.0 × 10 −2 to 4.0 × 10 0 s −1. In general the friction coefficients (m values) increase slightly with increasing the compressive strains even under the well-lubricated test conditions. The m values of the Al-Cu based alloys, including A2014, A2024 and IN9021, were almost same at 0.2~0.4 at the temperatures below 723K, but increased rapidly at the temperatures above 723K. On the other hand those of A6061 were almost constant at about 0.4 at the temperatures below 753K. The analysis based on the constitutive equation with consideration of the effect from an existence of the particles indicated that the dominant deformation mechanisms under the investigated conditions were dislocation creep for A2014, and were superplasticity for IN9021 except for the test condition at 573K with 1.0 × 10 −1 s −1. The m values of the IN9021 were lower than those of A2014, even if the flow stresses of IN9021 were higher than those of A2014. So it was concluded that the m value under a superplasticity region was lower than that under a dislocation creep region. It suggested that the superplastic forming had more benefits for the engineering applications.

Journal of Biomechanics, 2006

Journal of Biomechanics, 2006

Biomedizinische Technik/Biomedical Engineering, 2000

Biomedizinische Technik/Biomedical Engineering, 2000

Alloys based on titanium or cobalt have been used as implant materials for decades with good succ... more Alloys based on titanium or cobalt have been used as implant materials for decades with good success. Because of their natural oxide layer these alloys reveal good corrosion behaviour. In contact with physiological solution metal release takes place, which can cause inflammation. Coatings can improve the corrosion behaviour. In this study Ti6Al4V and Co28Cr6Mo alloys, which are frequently used as implant materials, were tested. Polished discs of these alloys and polished discs, which were coated with TiO2-layers by sol-gel chemistry, were compared regarding their corrosion behaviour and metal ion releasing. The releasing of Al, V, Ti, Co, Cr and Mo was quantified by ICP-MS analysis. The TiO2-coating reduced the release of all ions except of the Al-ion. Both alloys showed a deviating kinetic of ion releasing. In addition, cell response (cell vitality, cell proliferation, endothelial marker CD31 and actin allocation) of osteoblasts and endothelial cells were investigated.

Biomaterials, 2004

In comparison to the presently used alpha + beta titanium alloys for biomedical applications, bet... more In comparison to the presently used alpha + beta titanium alloys for biomedical applications, beta-titanium alloys have many advantageous mechanical properties, such as an improved wear resistance, a high elasticity and an excellent cold and hot formability. This will promote their future increased application as materials for orthopaedic joint replacements. Not all elements with beta-stabilizing properties in titanium alloys are suitable for biomaterial applications-corrosion and wear processes cause a release of these alloying elements to the surrounding tissue. In this investigation, the biocompability of alloying elements for beta- and near beta-titanium alloys was tested in order to estimate their suitability for biomaterial components. Titanium (grade 2) and the implant steel X2CrNiMo18153 (AISI 316 L) were tested as reference materials. The investigation included the corrosion properties of the elements, proliferation, mitochondrial activity, cell morphology and the size of MC3T3-E1 cells and GM7373 cells after 7 days incubation in direct contact with polished slices of the metals. The statistical significance was considered by Weir-test and Lord-test (alpha = 0.05). The biocompatibility range of the investigated metals is (decreasing biocompatibility): niobium-tantalum, titanium, zirconium-aluminium-316 L-molybdenum.