Molecular surface gradients can constitute electric field landscapes and serve to control local c... more Molecular surface gradients can constitute electric field landscapes and serve to control local cell adhesion and migration. Cellular responses to electric field landscapes may allow the discovery of routes to improve osseointegration of implants. Flat molecule aggregate landscapes of amine- or carboxyl-teminated dendrimers, amine-containing protein and polyelectrolytes were prepared on glass to provide lateral electric field gradients through their differing zeta potentials compared to the glass substrate. The local as well as the mesoscopic morphological responses of adhered osteoblasts (MG-63) with respect to the stripes were studied by means of Scanning Ion Conductance Microscopy (SICM) and Fluorescence Microscopy, in situ. A distinct spindle shape oriented parallel to the surface pattern as well as a preferential adhesion of the cells on the glass site have been observed at a stripe and spacing width of 20 μm. Excessive ruffling is observed at the spindle poles, where the cells...
The functionality of living cells is inherently linked to subunits with dimensions ranging from s... more The functionality of living cells is inherently linked to subunits with dimensions ranging from several micrometers down to the nanometer scale. The cell surface plays a particularly important role. Electric signaling, including information processing, takes place at the membrane, as well as adhesion and contact. For osteoblasts, adhesion and spreading are crucial processes with regard to bone implants. Here we present a comprehensive characterization of the 3D nanomorphology of living, as well as fixed, osteoblastic cells using scanning ion conductance microscopy (SICM), which is a nanoprobing method that largely avoids mechanical perturbations. Dynamic ruffles are observed, manifesting themselves in characteristic membrane protrusions. They contribute to the overall surface corrugation, which we systematically study by introducing the relative 3D excess area as a function of the projected adhesion area. A clear anticorrelation between the two parameters is found upon analysis of c...
INTRODUCTION One of the premises for biocompatibility studies of implant materials is the determi... more INTRODUCTION One of the premises for biocompatibility studies of implant materials is the determination of morphological characteristics of their modified surfaces. Our investigations here were focussed on the question if the physical and chemical parameters used for the description of the surface of commercially pure titanium with different roughness can be utilised for the prediction of the cellular behaviour of osteoblastic cells.
Due to their biodegradability, biocompatibility and sustainable nature, regenerated cellulose (RC... more Due to their biodegradability, biocompatibility and sustainable nature, regenerated cellulose (RC) films are of enormous relevance for green applications including medicinal, environmental and separation technologies. However, the processes used so far are very hazardous to the environment and health. Here, we disclose a simple, fast, environmentally friendly, nontoxic and cost-effective processing method for preparing RC films. High quality non-transparent and transparent RC films and powders can be produced by dissolution with tetrabutylphosphonium hydroxide [TBPH]/[TBP]+[OH]− followed by coagulation with organic carbonates. Investigations on the coagulation mechanism revealed an extremely fast reaction between the carbonates and the hydroxide ions. The high-quality powders and films were fully characterized with respect to structure, surface morphology, permeation and selectivity. This method represents a future-oriented green alternative to known industrial processes.
The titanium-osteoblast-interaction can be influenced both by surface roughness and by chemical m... more The titanium-osteoblast-interaction can be influenced both by surface roughness and by chemical modifications. We have ascertained that a positively charged titanium surface boosts osteoblast cells adhesion due to their negatively charged cellular hyaluronan coat. In current experiments, chemical surface modifications were combined with different topographies. Titanium disks of technical purity were modified (i) in their roughness by polishing (P), machining (M) and corundum blasting (CB), and (ii) by subsequently chemical functionalization by a thin film (d≤0.1 µm) of microwave plasma polymerized allylamine (PPAAm). In addition, collagen I was immobilized on PPAAm via the bifunctional linker polyethylene glycol diacid or glutar dialdehyde, respectively. The cell shape and material's contact of human osteoblasts was analyzed by FE-SEM and time dependent cell adhesion measured by flow cytometry. The cell dynamic of the adhesion component vinculin was observed in living cells. Ami...
... International Journal of Engineering Research in Africa. > @scientific.net. CONFERENCE. 9/... more ... International Journal of Engineering Research in Africa. > @scientific.net. CONFERENCE. 9/26/2011 - 9/30/2011 ISAM-2011: 12th International Syposium on Advanced Materials. 9/12/2011 - 9/15/2011 Euromat 2011. 4/9/2011 - 4/11/2011 ...
A nanoporous calcium phosphate (CaP) coating on metallic surfaces is presented. The coating consi... more A nanoporous calcium phosphate (CaP) coating on metallic surfaces is presented. The coating consists of a stack of (a) a TiNbN layer deposited by physical vapor deposition and acting as diffusion barrier against allergenic ions, (b) a SiO2 xerogel layer providing good adhesion properties and designing the nanoporosity of the outer CaP layer (c) precipitated electrochemically. SEM results verified a homogeneous nanoscale porous structure of the CaP coating. It is characterized by a high adhesion strength. If applied to stent covering the nanoporous CaP coating has promising properties to initiate rapid endothelium formation and reduced risk of restenosis.
Page 1. 3 Topological Surface Modifications 3.1 Patterning by Mechanical Treatment Bettina Hoffma... more Page 1. 3 Topological Surface Modifications 3.1 Patterning by Mechanical Treatment Bettina Hoffmann, Günter Ziegler, Regina Lange, and Ulrich Beck The interaction between implant material and biosystems (eg protein adsorption ...
Studies on bone cell ingrowth into synthetic, porous three-dimensional (3D) implants showed diffi... more Studies on bone cell ingrowth into synthetic, porous three-dimensional (3D) implants showed difficulties arising from impaired cellular proliferation and differentiation in the core region of these scaffolds with increasing scaffold volume in vitro. Therefore, we developed an in vitro perfusion cell culture module, which allows the analysis of cells in the interior of scaffolds under different medium flow rates. For each flow rate the cell viability was measured and compared with results from computer simulations that predict the local oxygen supply and shear stress inside the scaffold based on the finite element method. We found that the local cell viability correlates with the local oxygen concentration and the local shear stress. On the one hand the oxygen supply of the cells in the core becomes optimal with a higher perfusion flow. On the other hand shear stress caused by high flow rates impedes cell vitality, especially at the surface of the scaffold. Our results demonstrate th...
Titanium and Titanium alloys have been used widely and successfully for various types of load bea... more Titanium and Titanium alloys have been used widely and successfully for various types of load bearing bone-anchored implants. It has revealed that the surface topography has a great importance thereby. Also the properties of oxide films or calcium phosphate (CaP) coating covering these implant surfaces are important for the osseointegration [1–5].
The results presented show that GFS coatings can provide surface topology in the micron scale. Th... more The results presented show that GFS coatings can provide surface topology in the micron scale. Therefore, the coatings offer a potential of structuring the bone side of implants with adherent, biocompatible and microscopically rough layers which improves the osseointegration of implants.
International Journal of Computational Materials Science and Surface Engineering
A major challenge in biomaterials research is the regulation of protein adsorption which is a key... more A major challenge in biomaterials research is the regulation of protein adsorption which is a key factor for controlling the subsequent cell adhesion at implant surfaces. The aim of the present study was to control the adsorption of fibronectin (FN) and the attachment of MG-63 osteoblasts with an electronic nanostructure. Shallow doping line lattices with a period of 260 nm were produced for this purpose by implantation of phosphorous in silicon wafers. Protein coverage was determined after incubating the substrate with FN by means of an immunostaining procedure and the measurement of the fluorescence intensity with a TECAN analyzer. We observed an increased amount of adsorbed FN on the nanostructure compared to control substrates. MG-63 osteoblasts were cultivated for 24h on FN-incubated substrates and their morphology was assessed by SEM. Preferred orientation and elongation of the cells in direction of the doping lattice lines was observed on FN-coated nanostructures.
Molecular surface gradients can constitute electric field landscapes and serve to control local c... more Molecular surface gradients can constitute electric field landscapes and serve to control local cell adhesion and migration. Cellular responses to electric field landscapes may allow the discovery of routes to improve osseointegration of implants. Flat molecule aggregate landscapes of amine- or carboxyl-teminated dendrimers, amine-containing protein and polyelectrolytes were prepared on glass to provide lateral electric field gradients through their differing zeta potentials compared to the glass substrate. The local as well as the mesoscopic morphological responses of adhered osteoblasts (MG-63) with respect to the stripes were studied by means of Scanning Ion Conductance Microscopy (SICM) and Fluorescence Microscopy, in situ. A distinct spindle shape oriented parallel to the surface pattern as well as a preferential adhesion of the cells on the glass site have been observed at a stripe and spacing width of 20 μm. Excessive ruffling is observed at the spindle poles, where the cells...
The functionality of living cells is inherently linked to subunits with dimensions ranging from s... more The functionality of living cells is inherently linked to subunits with dimensions ranging from several micrometers down to the nanometer scale. The cell surface plays a particularly important role. Electric signaling, including information processing, takes place at the membrane, as well as adhesion and contact. For osteoblasts, adhesion and spreading are crucial processes with regard to bone implants. Here we present a comprehensive characterization of the 3D nanomorphology of living, as well as fixed, osteoblastic cells using scanning ion conductance microscopy (SICM), which is a nanoprobing method that largely avoids mechanical perturbations. Dynamic ruffles are observed, manifesting themselves in characteristic membrane protrusions. They contribute to the overall surface corrugation, which we systematically study by introducing the relative 3D excess area as a function of the projected adhesion area. A clear anticorrelation between the two parameters is found upon analysis of c...
INTRODUCTION One of the premises for biocompatibility studies of implant materials is the determi... more INTRODUCTION One of the premises for biocompatibility studies of implant materials is the determination of morphological characteristics of their modified surfaces. Our investigations here were focussed on the question if the physical and chemical parameters used for the description of the surface of commercially pure titanium with different roughness can be utilised for the prediction of the cellular behaviour of osteoblastic cells.
Due to their biodegradability, biocompatibility and sustainable nature, regenerated cellulose (RC... more Due to their biodegradability, biocompatibility and sustainable nature, regenerated cellulose (RC) films are of enormous relevance for green applications including medicinal, environmental and separation technologies. However, the processes used so far are very hazardous to the environment and health. Here, we disclose a simple, fast, environmentally friendly, nontoxic and cost-effective processing method for preparing RC films. High quality non-transparent and transparent RC films and powders can be produced by dissolution with tetrabutylphosphonium hydroxide [TBPH]/[TBP]+[OH]− followed by coagulation with organic carbonates. Investigations on the coagulation mechanism revealed an extremely fast reaction between the carbonates and the hydroxide ions. The high-quality powders and films were fully characterized with respect to structure, surface morphology, permeation and selectivity. This method represents a future-oriented green alternative to known industrial processes.
The titanium-osteoblast-interaction can be influenced both by surface roughness and by chemical m... more The titanium-osteoblast-interaction can be influenced both by surface roughness and by chemical modifications. We have ascertained that a positively charged titanium surface boosts osteoblast cells adhesion due to their negatively charged cellular hyaluronan coat. In current experiments, chemical surface modifications were combined with different topographies. Titanium disks of technical purity were modified (i) in their roughness by polishing (P), machining (M) and corundum blasting (CB), and (ii) by subsequently chemical functionalization by a thin film (d≤0.1 µm) of microwave plasma polymerized allylamine (PPAAm). In addition, collagen I was immobilized on PPAAm via the bifunctional linker polyethylene glycol diacid or glutar dialdehyde, respectively. The cell shape and material's contact of human osteoblasts was analyzed by FE-SEM and time dependent cell adhesion measured by flow cytometry. The cell dynamic of the adhesion component vinculin was observed in living cells. Ami...
... International Journal of Engineering Research in Africa. > @scientific.net. CONFERENCE. 9/... more ... International Journal of Engineering Research in Africa. > @scientific.net. CONFERENCE. 9/26/2011 - 9/30/2011 ISAM-2011: 12th International Syposium on Advanced Materials. 9/12/2011 - 9/15/2011 Euromat 2011. 4/9/2011 - 4/11/2011 ...
A nanoporous calcium phosphate (CaP) coating on metallic surfaces is presented. The coating consi... more A nanoporous calcium phosphate (CaP) coating on metallic surfaces is presented. The coating consists of a stack of (a) a TiNbN layer deposited by physical vapor deposition and acting as diffusion barrier against allergenic ions, (b) a SiO2 xerogel layer providing good adhesion properties and designing the nanoporosity of the outer CaP layer (c) precipitated electrochemically. SEM results verified a homogeneous nanoscale porous structure of the CaP coating. It is characterized by a high adhesion strength. If applied to stent covering the nanoporous CaP coating has promising properties to initiate rapid endothelium formation and reduced risk of restenosis.
Page 1. 3 Topological Surface Modifications 3.1 Patterning by Mechanical Treatment Bettina Hoffma... more Page 1. 3 Topological Surface Modifications 3.1 Patterning by Mechanical Treatment Bettina Hoffmann, Günter Ziegler, Regina Lange, and Ulrich Beck The interaction between implant material and biosystems (eg protein adsorption ...
Studies on bone cell ingrowth into synthetic, porous three-dimensional (3D) implants showed diffi... more Studies on bone cell ingrowth into synthetic, porous three-dimensional (3D) implants showed difficulties arising from impaired cellular proliferation and differentiation in the core region of these scaffolds with increasing scaffold volume in vitro. Therefore, we developed an in vitro perfusion cell culture module, which allows the analysis of cells in the interior of scaffolds under different medium flow rates. For each flow rate the cell viability was measured and compared with results from computer simulations that predict the local oxygen supply and shear stress inside the scaffold based on the finite element method. We found that the local cell viability correlates with the local oxygen concentration and the local shear stress. On the one hand the oxygen supply of the cells in the core becomes optimal with a higher perfusion flow. On the other hand shear stress caused by high flow rates impedes cell vitality, especially at the surface of the scaffold. Our results demonstrate th...
Titanium and Titanium alloys have been used widely and successfully for various types of load bea... more Titanium and Titanium alloys have been used widely and successfully for various types of load bearing bone-anchored implants. It has revealed that the surface topography has a great importance thereby. Also the properties of oxide films or calcium phosphate (CaP) coating covering these implant surfaces are important for the osseointegration [1–5].
The results presented show that GFS coatings can provide surface topology in the micron scale. Th... more The results presented show that GFS coatings can provide surface topology in the micron scale. Therefore, the coatings offer a potential of structuring the bone side of implants with adherent, biocompatible and microscopically rough layers which improves the osseointegration of implants.
International Journal of Computational Materials Science and Surface Engineering
A major challenge in biomaterials research is the regulation of protein adsorption which is a key... more A major challenge in biomaterials research is the regulation of protein adsorption which is a key factor for controlling the subsequent cell adhesion at implant surfaces. The aim of the present study was to control the adsorption of fibronectin (FN) and the attachment of MG-63 osteoblasts with an electronic nanostructure. Shallow doping line lattices with a period of 260 nm were produced for this purpose by implantation of phosphorous in silicon wafers. Protein coverage was determined after incubating the substrate with FN by means of an immunostaining procedure and the measurement of the fluorescence intensity with a TECAN analyzer. We observed an increased amount of adsorbed FN on the nanostructure compared to control substrates. MG-63 osteoblasts were cultivated for 24h on FN-incubated substrates and their morphology was assessed by SEM. Preferred orientation and elongation of the cells in direction of the doping lattice lines was observed on FN-coated nanostructures.
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