Kurosch Rezwan
Research interests
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InterestsBioceramics, Advanced Ceramics, advanced composites, Biofunctionalisation
Publications
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1.91Impact points
Osteoblast viability on hydroxyapatite with well-adjusted submicron and micron surface roughness as monitored by the proliferation reagent WST-1.
Journal of biomaterials applications. 01/2012;
The impact of the cell surface roughness on titanium alloys used for biomedical implants has been extensively studied, whereas the dependency of human osteoblast viability on hydroxyapatite (HA) submicron and micron surface roughness has hitherto not yet been investigated in detail. Therefore, we in... [more] The impact of the cell surface roughness on titanium alloys used for biomedical implants has been extensively studied, whereas the dependency of human osteoblast viability on hydroxyapatite (HA) submicron and micron surface roughness has hitherto not yet been investigated in detail. Therefore, we investigate in this study the effect of HA substrates with different well-adjusted surface roughness on human osteoblast proliferation using the standard colorimetric reagent WST-1. By grinding, we obtained HA surfaces with six levels of well-defined surface roughness ranging from Sa = 3.36 µm down to 0.13 µm, resulting in hydrophilic contact angles from 11° to 27°. Energy dispersive X-ray spectroscopy, X-ray diffraction, and X-ray fluorescence measurements confirmed that neither grinding paper residues nor changes of the crystal structure were introduced to the HA substrates by the grinding process. By applying this simple surface treatment, we were able to isolate other effects from surface chemistry, crystal structure, and relative density. The changes of the osteoblast proliferation (WST-1 assay) on these different roughened HA surfaces after 7 days were found to be insignificant (p > 0.05), evaluated by one-way analysis of variance and Tuckey's Multiple Comparison Method. The results of this study show that all roughened HA surfaces, regardless of the microtopography, are biocompatible and allow osteoblast attachment, proliferation, and collagen type I production. The comparison with surface roughness used for standard Ti-based implants yielded that for HA no finishing process is necessary to ensure a sound human osteoblast cell proliferation in vitro.
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3.98Impact points
Fluorescence labeling of colloidal core-shell particles with defined isoelectric points for in vitro studies.
Acta biomaterialia. 11/2011; 8(2):720-7.
In the light of in vitro nanotoxicological studies fluorescence labeling has become standard for particle localization within the cell environment. However, fluorescent labeling is also known to significantly alter the particle surface chemistry and therefore potentially affect the outcome of cell s... [more] In the light of in vitro nanotoxicological studies fluorescence labeling has become standard for particle localization within the cell environment. However, fluorescent labeling is also known to significantly alter the particle surface chemistry and therefore potentially affect the outcome of cell studies. Hence, fluorescent labeling is ideally carried out without changing, for example, the isoelectric point. A simple and straightforward method for obtaining fluorescently labeled spherical metal oxide particles with well-defined isoelectric points and a narrow size distribution is presented in this study. Spherical amorphous silica (SiO2, 161 nm diameter) particles were used as the substrate material and were coated with silica, alumina (Al2O3), titania (TiO2), or zirconia (ZrO2) using sol-gel chemistry. Fluorescent labeling was achieved by directly embedding rhodamine 6G dye in the coating matrix without affecting the isoelectric point of the metal oxide coatings. The coating quality was confirmed by high resolution transmission electron microscopy, energy filtered transmission electron microscopy and electrochemical characterization. The coatings were proven to be stable for at least 240 h under different pH conditions. The well-defined fluorescent particles can be directly used for biomedical investigations, e.g. elucidation of particle-cell interactions in vitro.
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3.98Impact points
Protein adsorption on colloidal alumina particles functionalized with amino, carboxyl, sulfonate and phosphate groups.
Acta biomaterialia. 09/2011; 8(3):1221-9.
Colloidal oxide particles in biomedical or biotechnological applications immediately become coated with proteins of the biological medium, a process which is strongly influenced by the surface characteristics of the particles. Fundamental correlations between surface characteristics and the, so far ... [more] Colloidal oxide particles in biomedical or biotechnological applications immediately become coated with proteins of the biological medium, a process which is strongly influenced by the surface characteristics of the particles. Fundamental correlations between surface characteristics and the, so far mainly uncontrollable, protein adsorption are still not clear. In this study the surface of colloidal alumina particles (d(50)=179 ± 8 nm) was systematically adjusted with NH(2), COOH, SO(3)H and PO(3)H(2) functional groups to investigate the influence on the adsorption of the three model proteins, bovine serum albumin (BSA), lysozyme (LSZ) and trypsin (TRY). The surface functionalization is characterized and discussed in detail with regard to the morphology, isoelectric point, zeta potential, hydrophilic/hydrophobic properties, functional group density and stability. Protein-particle interaction was then assessed by evaluating the amount of protein adsorbed and the zeta potentials of protein-particle conjugates. Protein adsorption was found to be influenced by the type of functional group as well as the expected electrostatic forces under the given experimental conditions. The level of protein adsorption might, hence, be specifically controlled by the type of surface functionalization. Possible adsorption modes of BSA, LSZ and TRY on the particles are suggested by considering the spatial surface potential distribution of the proteins calculated from the protein database file. The particles presented provide an excellent prerequisite for further investigation of fundamental particle-protein interactions and the design of functionally graded materials for biomedical and biotechnological applications, e.g. as drug carriers or for protein purification.
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3.98Impact points
Orientation of human osteoblasts on hydroxyapatite-based microchannels.
Acta biomaterialia. 08/2011; 8(1):394-403.
The effect of calcium phosphate-based microchannels on the growth and orientation of human osteoblast cells is investigated in this study. As substrates, hydroxyapatite-based microchannels with high contouring accuracy were fabricated by a novel micro-moulding technique. Microchannels obtained by th... [more] The effect of calcium phosphate-based microchannels on the growth and orientation of human osteoblast cells is investigated in this study. As substrates, hydroxyapatite-based microchannels with high contouring accuracy were fabricated by a novel micro-moulding technique. Microchannels obtained by this method featured widths ranging from 16.0±0.7 to 76.6±1.4 μm and depths from 7.9±0.8 to 15.5±1.3 μm. Surface and contour characterization was carried out using X-ray diffraction analysis, scanning electron microscopy imaging and 3D-confocal profilometry. Cell activity and alignment on microchannels with different widths were determined after 1 and 3 days by photometric spectroscopy and fluorescence microscopic imaging and statistically analysed by Tukey's multiple comparison test. On days 1 and 3 for microchannels of width 16 and 30 μm, 70-80% of the osteoblasts oriented within an angular range of 0-15° relative to the microchannel direction. Interestingly, only 20% of the cells grew inside the microchannels for channel widths of 16 and 30 μm. Substrates with channel widths of 45, 65 and 76 μm allowed ∼40% of the cells to grow inside. The depth of the microchannel showed hardly any significant impact. All micropatterned surfaces provoked a good cell attachment, as flat and spread cell morphologies with lamellipodiae and filopodiae could already be observed after 1 day. The effect of the microchannels on osteoblast activity was determined using the colorimetric WST-1 assay. In addition, the cell differentiation was assessed by collagen type I staining. The cell activity obtained by WST-1 assay differed insignificantly for all micropatterned samples of various widths and depths. The assessment of collagen type I yielded the same amounts for all micropatterned samples after 1, 3 and 7 days. In summary, the microchannel width of HA-based patterns has a distinct effect on the directed growth of human osteoblast cells, allowing novel design strategies for surfaces such as dental implants.
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3.90Impact points
Adsorption and reduction of glutathione disulfide on α-Al2O3 nanoparticles: experiments and modeling.
Langmuir : the ACS journal of surfaces and colloids. 06/2011; 27(15):9449-57.
Glutathione disulfide (GSSG; γ-GluCysGly disulfide) was used as a physiologically relevant model molecule to investigate the fundamental adsorption mechanisms of polypeptides onto α-alumina nanoparticles. Its adsorption/desorption behavior was studied by enzymatic quantification of the bound GSSG co... [more] Glutathione disulfide (GSSG; γ-GluCysGly disulfide) was used as a physiologically relevant model molecule to investigate the fundamental adsorption mechanisms of polypeptides onto α-alumina nanoparticles. Its adsorption/desorption behavior was studied by enzymatic quantification of the bound GSSG combined with zeta potential measurements of the particles. The adsorption of GSSG to alumina nanoparticles was rapid, was prevented by alkaline pH, was reversed by increasing ionic strength, and followed a nearly ideal Langmuir isotherm with a standard Gibbs adsorption energy of -34.7 kJ/mol. Molecular dynamics simulations suggest that only one of the two glutathionyl moieties contained in GSSG binds stably to the nanoparticle surface. This was confirmed experimentally by the release of GSH from the bound GSSG upon reducing its disulfide bond with dithiothreitol. Our data indicate that electrostatic interactions via the carboxylate groups of one of the two glutathionyl moieties of GSSG are predominantly responsible for the binding of GSSG to the alumina surface. The results and conclusions presented here can provide a base for further experimental and modeling studies on the interactions of biomolecules with ceramic materials.
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3.14Impact points
Uptake of dimercaptosuccinate-coated magnetic iron oxide nanoparticles by cultured brain astrocytes.
Nanotechnology. 02/2011; 22(14):145101.
Magnetic iron oxide nanoparticles (Fe-NP) are currently considered for various diagnostic and therapeutic applications in the brain. However, little is known on the accumulation and biocompatibility of such particles in brain cells. We have synthesized and characterized dimercaptosuccinic acid (DMSA... [more] Magnetic iron oxide nanoparticles (Fe-NP) are currently considered for various diagnostic and therapeutic applications in the brain. However, little is known on the accumulation and biocompatibility of such particles in brain cells. We have synthesized and characterized dimercaptosuccinic acid (DMSA) coated Fe-NP and have investigated their uptake by cultured brain astrocytes. DMSA-coated Fe-NP that were dispersed in physiological medium had an average hydrodynamic diameter of about 60 nm. Incubation of cultured astrocytes with these Fe-NP caused a time- and concentration-dependent accumulation of cellular iron, but did not lead within 6 h to any cell toxicity. After 4 h of incubation with 100-4000 µM iron supplied as Fe-NP, the cellular iron content reached levels between 200 and 2000 nmol mg⁻¹ protein. The cellular iron content after exposure of astrocytes to Fe-NP at 4 °C was drastically lowered compared to cells that had been incubated at 37 °C. Electron microscopy revealed the presence of Fe-NP-containing vesicles in cells that were incubated with Fe-NP at 37 °C, but not in cells exposed to the nanoparticles at 4 °C. These data demonstrate that cultured astrocytes efficiently take up DMSA-coated Fe-NP in a process that appears to be saturable and strongly depends on the incubation temperature.
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Micromachining of Ceramic Surfaces: Hydroxyapatite and Zirconia
Journal of Mater. Process. Technol. 01/2011;
Computerised Numerical Control (CNC) precision machining can be employed as a fast and reproducible method for surface micropatterning. For biomedical applications an efficient and reproducible micropatterning of zirconia and calcium phosphate based materials is highly sought in order to guide impla... [more] Computerised Numerical Control (CNC) precision machining can be employed as a fast and reproducible method for surface micropatterning. For biomedical applications an efficient and reproducible micropatterning of zirconia and calcium phosphate based materials is highly sought in order to guide implant interactions with surrounding biological tissues for a better osseointegration. Therefore, CNC precision machining of zirconia and hydroxyapatite substrates is investigated in this study and optimised process parameters are reported. By microgrinding and micromilling microgrooves with a minimum width of 100 m were obtained and process parameters such as cutting tool diameter and feed velocity discussed. As all samples were sintered prior to the micropatterning process, the influence of sintering temperature on the pattern quality, size and hardness of the obtained samples are studied. Vickers hardness of the different sintered ceramic surfaces was measured to correlate the possible wear impact on the tip of the cutting tools. The stiffness and the hardness of the used cutting tools were measured and their effect on the cutting results was discussed. The pattern quality and the average roughness in the machined microgrooves were analysed by 3D-profilometry and imaged by SEM. Comparison of the two machining techniques yielded more defined and less fractured micropatterns for microgrinding. The process efficiency for both methods was limited by the economic life time of the tool tips. For CNC grinding the life time was downsized due to more pronounced abrasive wear. For both materials the hardness was the crucial process parameter, which was adjusted by the sintering temperature. For milling of zirconia the sintering should not exceed a temperature of 1100 ◦C to minimize tool wear. A temperature of lower 1200 ◦C is suggested for the milling of HA. For sintering temperatures higher than 1200 ◦C the machining of both ceramic surfaces was hardly possible. The feed velocity was found not having a significant influence on the obtained micropattern width. The preset line pitch of 100 m was excellently reached for both applied machining processes. It was found that lower feed velocities and smaller tool diameters caused deeper micropatterns.
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Ultraviolet Laser Interference Patterning of Hydroxyapatite Surfaces
Applied Surface Science. 01/2011; 257(7):3081-3087.
Direct laser interference patterning (DLIP) was used to produce periodic patterns on hydroxyapatite. A Nd:YAG laser operating at 266 and 355nm wavelengths and a pulse duration of 10 ns was used in these experiments. Line- and cross-like patterns with periodical distances of 10 and 20 mwere fabricate... [more] Direct laser interference patterning (DLIP) was used to produce periodic patterns on hydroxyapatite. A Nd:YAG laser operating at 266 and 355nm wavelengths and a pulse duration of 10 ns was used in these experiments. Line- and cross-like patterns with periodical distances of 10 and 20 mwere fabricated with energy densities between 0.6 and 2.4 J/cm2, and pulse numbers from 1 to 100. In the low/middle laser intensity range it was observed that the structure depth increased with the pulse number. However, for higher energies the patterns smudge due to thermal effects. For single pulse laser experiments, increasing of the laser fluence did not produce deeper structures. In addition, the best results were obtained when using low-medium laser intensities (∼0.6–1.2 J/cm2) and moderate number of laser pulses (20–50), depending on laser wavelength. In addition, at a 355nm wavelength only patterns with 20 m periods presented a good quality structure. In contrast, 266nm wavelengths permitted to improve resolution up to periods of 10 m due to a higher photochemical contribution to the ablation process. X-ray Photoelectron Spectroscopy (XPS) analysis showed that there are no significant changes in the chemical composition of laser-treated hydroxyapatite.
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Orientation of Human Osteoblasts on Hydroxyapatite-based Microchannels
Acta Biomaterialia. 01/2011;
The effect of calcium phosphate-based microchannels on the growth and orientation of human osteoblast cells is investigated in this study. As substrates hydroxyapatite-based microchannels with high contouring accuracy were fabricated by a novel micro molding technique. Microchannels obtained by this... [more] The effect of calcium phosphate-based microchannels on the growth and orientation of human osteoblast cells is investigated in this study. As substrates hydroxyapatite-based microchannels with high contouring accuracy were fabricated by a novel micro molding technique. Microchannels obtained by this method featured widths ranging from 16.0 ± 0.7
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Comparison of micropatterning methods for ceramic surfaces
J. Europ. Ceram. Soc. 01/2011; 31:2809-2817.
The fabrication of defined ceramic micropatterns smaller than 100 m is due to the hardness and brittleness of ceramic materials still very challenging. However, in recent years, micropatterned ceramic surfaces have become highly interesting for biomedical applications or the fabrication of energy co... [more] The fabrication of defined ceramic micropatterns smaller than 100 m is due to the hardness and brittleness of ceramic materials still very challenging. However, in recent years, micropatterned ceramic surfaces have become highly interesting for biomedical applications or the fabrication of energy converting devices, such as solid oxide fuel or solar cells. In this study we evaluate six modern techniques for ceramic pattern fabrication with feature sizes ranging from 5 to 100 m. Ceramic materials such as alumina, zirconia, silica and hydroxyapatite are discussed. Advantages and disadvantages for each process are highlighted and compared to the other techniques. Three of these techniques, namely microtransfer molding, modified micromolding and Aerosol-Jet® printing generate patterns starting with aqueous ceramic suspensions. The other three techniques, micromachining and two different types of laser treatment produce micropatterns by material removal from solid ceramic substrates. The detailed analysis yields that properties such as the desired micropatterning size, shape or the production time are strongly dependant on the chosen technique. © 2011 Elsevier Ltd. All rights reserved.
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Versatile Crack-free Ceramic Micropatterns Mady by a Modified Moulding Technique (m-µM)
J. Am. Ceram. Soc. 01/2010; 93(9):2574-2578.
Crack-free ceramic micropatterns made of oxidic ceramic powders, e.g. alumina, titania, zirconia, and nonoxidic calciumphosphate ceramic powders were fabricated by a novel, simple, and low-cost modified micromolding (m-lM) technique via polydimethylsiloxane stamps. By means of this m-lMtechnique it ... [more] Crack-free ceramic micropatterns made of oxidic ceramic powders, e.g. alumina, titania, zirconia, and nonoxidic calciumphosphate ceramic powders were fabricated by a novel, simple, and low-cost modified micromolding (m-lM) technique via polydimethylsiloxane stamps. By means of this m-lMtechnique it is possible to fabricate monolithic ceramic bodies with a micropatterned surface with very high accuracy on surface detail. Our produced micropatterns can feature various geometries, e.g. cylinders, holes, channels, and struts with diameters ranging from 8 to 140 lm in diameter or widths and from 8 to 30 lm in depth or height. The oxidic and nonoxidic ceramic micropatterns could be removed from the molds and dried without any cracks. Even after sintering, these micropatterned samples showed no cracks or fissures. The reported technique has a very high potential for fully automatized up-scale fabrication of micropatterned ceramic surfaces.
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Einfluss mikrobieller Lasten auf wassergemischte Kühlschmierstoffe und das Zerspanergebnis
Tribologie + Schmierungstechnik. 01/2010; 57(3):21-26.
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Development and characterisation of functionalised ceramic microtubes for bacteria filtration
J. Membrane Science. 01/2010; 365:447-455.
A very challenging objective of today’s research in the membrane technology for microfiltration applications is the development and processing of ceramic microtubes which are especially attractive due to their excellent chemical, thermal and mechanical properties compared to polymeric membranes. Ano... [more] A very challenging objective of today’s research in the membrane technology for microfiltration applications is the development and processing of ceramic microtubes which are especially attractive due to their excellent chemical, thermal and mechanical properties compared to polymeric membranes. Another challenge is the fabrication of self-cleaning membranes to avoid blockage of filtering pores and to ensure a long service life. In this studywepresent the fabrication of zirconia microtubes featuring a specific surface functionalisation for bacteria filtration and digestion, using a sequence of slurry preparation, extrusion process, final sintering and subsequent surface modification. Tubular zirconia membranes with 1.6 and 1.0mm outer and inner diameters, respectively, were extruded and sintered at temperatures between 950 ◦C and 1250 ◦C after a debinding step. The ceramic microtubes were characterised by microstructural analysis including Hg intrusion porosimetry, BET analysis, strength tests and profilometer measurements. A sintering temperature of 1050 ◦C was found to provide membrane properties featuring an open porosity of 51.3% with pore sizes ≤0.2 m, a BET surface area of 7.85m2/g and an average bending strength of 57.0 MPa, being suitable for bacteria filtration. In addition, a straightforward procedure for heterogeneous membrane functionalisation using an acid hydroxylation pre-treatment, followed by utilisation of 3-aminopropyltriethoxysilane (APTES) and finally immobilisation of the antibacterial model enzyme lysozyme was successfully realised.
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Bovine Serum Albumin and Lysozyme Adsorption on Calcium Phosphate Particles
Advanced Engineering Materials (Inside Cover Page). 01/2010; 12(1-2):B53 - B61.
Two model proteins that are oppositely charged at neutral pH – bovine serum albumin (BSA) and lysozyme, with acidic and alkaline isoelectric points, respectively – are used to investigate the protein adsorption behaviour of hydroxyapatite and beta-tricalcium phosphate (b-TCP) particles. Both calcium... [more] Two model proteins that are oppositely charged at neutral pH – bovine serum albumin (BSA) and lysozyme, with acidic and alkaline isoelectric points, respectively – are used to investigate the protein adsorption behaviour of hydroxyapatite and beta-tricalcium phosphate (b-TCP) particles. Both calcium phosphate based particles are highly relevant for the fabrication of bioactive and resorbable bone implants. The investigations are carried out by combining zeta potential and Vis spectroscopy measurements. The changes of zeta potential and isoelectric point are determined as a function of added protein. Both proteins form a monolayer on b-TCP, while on hydroxyapatite only semimonolayers were measured. For BSA, a side-on adsorption mode is suggested, whereas end-on adsorption appears to be most likely for lysozyme. The zeta potential curves as a function of adsorbed protein show that plateaus of the protein amounts adsorbed increase with charge saturation. In addition, the spatial charge distribution of both proteins is modelled to get a further understanding of the initial adsorption orientation of the biomolecules, supporting the findings from the experimental data. The reported findings can be transferred to the adsorption behaviour of a variety of proteins on calcium phosphate surfaces and are helpful for the fabrication of bone-analogous calcium phosphate/ protein nanocomposites.
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3.90Impact points
Control of alpha-Alumina Surface Charge with Carboxylic Acids.
Langmuir : the ACS journal of surfaces and colloids. 12/2009;
In this work, we studied the surface charge of alpha-alumina treated with carboxylic acids with different carbon chain length. The results show the possibility of controlling surface charges of alumina by using different concentrations of carboxylic acids or changing the size of the carbon chain of ... [more] In this work, we studied the surface charge of alpha-alumina treated with carboxylic acids with different carbon chain length. The results show the possibility of controlling surface charges of alumina by using different concentrations of carboxylic acids or changing the size of the carbon chain of the acids. We also report that part of the acid found on the surface is strongly bound, therefore making it possible to obtain pH-resistant samples of alpha-alumina with an isoelectric point (IEP) of 5.5. It is found, that IEP values obtained for modified samples have a linear correlation with the number of carbon atoms of dicarboxylic acids for up to five carbon atoms. From a practical perspective, the method presented in this work has many advantages. First, it maintains the same hydrophilicity of the alumina surface. Second, the modification of the surface is stable in a long-range of pH. Finally, the presented method is easy-to-use and cheap, as the modification consists of only two simple steps carried out at low temperatures with inexpensive and nontoxic reagents.
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Hydroxylapatite / SiO2 composites via freeze casting for bone tissue engineering
Advanced Engineering Materials (Cover Page). 01/2009; 11(11):875 - 884.
Freeze casting is a fabrication method that allows producing near-net-shaped ceramics with variable porosity. Hydroxyapatite (HA) was modified by the addition of different amounts of SiO2 nanoparticles during freeze cast preparation. The addition of SiO2 introduced a partial phase transformation of ... [more] Freeze casting is a fabrication method that allows producing near-net-shaped ceramics with variable porosity. Hydroxyapatite (HA) was modified by the addition of different amounts of SiO2 nanoparticles during freeze cast preparation. The addition of SiO2 introduced a partial phase transformation of HA to -tricalcium phosphate and improved the form stability due to less shrinkage after sintering. The impact of surface roughness of pure HA ceramics and the influence of SiO2 introduction during freeze casting on adhesion, proliferation, and differentiation of human osteoblast-like cells (MG-63) was investigated. While both cell attachment and proliferation of smooth pressed HA was significantly enhanced compared to rough freeze cast HA, the addition of SiO2 improved the cell numbers of the latter. The expression of cell differentiation markers osteocalcin and collagen I was found to be supported by rough surfaces (Ra = 5-6 µm) in particular on ceramics containing SiO2
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Comparison of Three Microstructure Fabrication Methods for Bone Cell Growth Studies
Msec 2008: Proceedings of the Asme International Manufacturing Science and Engineering Conference 2008. 01/2009; 2:483-490.
Different micropatterning techniques were applied to elucidate the potential for cell proliferation studies on calcium phosphate surfaces. Sintered hydroxyapatite (HA) platelets were microstructured by three different techniques: Aerosol jet printing (M-3 D (R)), laser ablation and microcontact prin... [more] Different micropatterning techniques were applied to elucidate the potential for cell proliferation studies on calcium phosphate surfaces. Sintered hydroxyapatite (HA) platelets were microstructured by three different techniques: Aerosol jet printing (M-3 D (R)), laser ablation and microcontact printing via polydimethylsiloxane (PDMS) stamps. The microstructures were designed as channels between 1000 and 3000 micron in length, 10 to 220 micron in width and 5 to 110 micron in height. An optical profilometer, a Scanning Electron Microscope (SEM) and X-ray diffraction were used to characterize the microstructures. Cell proliferation tests were carried out by incubating the microstructured ceramic samples in complete cell media for a maximum of seven days. Osteoblast-like cells (MG-63) were used for testing. Each sample was immersed in media in which the cells were already seeded. Imaging was performed by SEM and Fluorescence Microscopy. The cells proliferated on all three differently fabricated microstructures. Cell growth was observed in the microchannels as well as on the microchannel walls or spacers. In particular it turned out, that the microtopology can provoke the cells to elongate aligned to the direction of the microchannels. Non-directional growth was observed oil non-structured areas. All three differently fabricated hydroxyapatite microstructuring methods seem to be attractive and promising techniques for use in bone cell growth studies. The applied fabrication techniques show many advantages for fundamental research in the field of cell interaction with ceramic microstructures and may exhibit possible methods of structuring implant surfaces.
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Microstructuring and Biofunctionalisation of Alumina Surfaces to enhance Abrasion Resistance and Supress Bacterial Biofilm Growth
Msec 2008: Proceedings of the Asme International Manufacturing Science and Engineering Conference 2008. 01/2009; 2:475-482.
The design and fabrication of alumina microstructured surfaces that simultaneously present high mechanical and chemical features and do not suffer biofouling are here reported. An aerosol based patterning technique was employed to fabricate alumina microstructures directly on alumina Surfaces with t... [more] The design and fabrication of alumina microstructured surfaces that simultaneously present high mechanical and chemical features and do not suffer biofouling are here reported. An aerosol based patterning technique was employed to fabricate alumina microstructures directly on alumina Surfaces with the aim to enhance wear and chemical resistance. Microstructured alumina surfaces were subsequently biofunctionalised with antibacterial biomolecules to inhibit bacterial adhesion. Lysozyme, an antibacterial enzyme commonly found in body secretions, was used as antibacterial agent and directly deposited onto microstructured alumina surfaces. Lysozyme-biofunctionalised microstructured alumina surfaces were tested at flow condition using abrasive particles and viable bacteria. The very preliminary results showed that alumina microstructures presented high resistance against mechanical abrasion and that bacterial biofilm formation could be suppressed. In particular alumina microstructures protected lysozyme molecules from desorption and loss of enzymatic activity. Such biofunctionalised microstructures present a promising system for fundamental research in the field of biomolecule adsorption on Surfaces and maybe a feasible alternative e. to protect Surfaces of water transport systems where abrasive particles and microorganisms are present.
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Antibacterial and Abrasion-Resistant Alumina Micropatterns
Advanced Engineering Materials (Inside Cover Page). 01/2009; 11(7):B61-B66.
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2.82Impact points
Collagen release kinetics of surface functionalized 45S5 Bioglass(R)-based porous scaffolds.
Journal of biomedical materials research. Part A. 01/2008;
A highly interconnected porous scaffold made from 45S5 Bioglass(R) was fabricated by the polymer replica technique and surface functionalized for protein immobilization. Subsequently rat-tail collagen type I was immobilized on the scaffolds. The protein and ion release rates were determined by UV-vi... [more] A highly interconnected porous scaffold made from 45S5 Bioglass(R) was fabricated by the polymer replica technique and surface functionalized for protein immobilization. Subsequently rat-tail collagen type I was immobilized on the scaffolds. The protein and ion release rates were determined by UV-vis spectroscopy and ion chromatography, respectively, and the impact on hydroxyapatite (HA) formation on the scaffolds upon immersion in SBF was evaluated. It was discovered that the surface functionalization enhanced the stability of the collagen attachment and stability against the increment of pH in a biological environment, resulting in similar collagen release kinetics in solutions of different pH values. Without the surface modification, collagen release was considerably expedited by the increment of pH in a surrounding solution. It was also found that the collagen immobilization does not effect the formation of carbonated HA on the scaffold surface. The stable collagen attachment to the functionalized scaffold makes this approach potentially suitable for improving cell attachment and thus for enhancing the application potential of the scaffold in tissue engineering. (c) 2007 Wiley Periodicals, Inc. J Biomed Mater Res 2007.
Following (1)
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Leif Schröder
Leibniz-Institut für Molekulare Pharmakologie (FMP)
