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Simon P, Pompe W, Gruner D, Sturm E, Ostermann K, Matys S, Vogel M, Rödel G. Nested Formation of Calcium Carbonate Polymorphs in a Bacterial Surface Membrane with a Graded Nanoconfinement: An Evolutionary Strategy to Ensure Bacterial Survival. ACS Biomater Sci Eng 2022; 8:526-539. [PMID: 34995442 PMCID: PMC8848282 DOI: 10.1021/acsbiomaterials.1c01280] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
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It is the intention
of this study to elucidate the nested formation
of calcium carbonate polymorphs or polyamorphs in the different nanosized
compartments. With these observations, it can be concluded how the
bacteria can survive in a harsh environment with high calcium carbonate
supersaturation. The mechanisms of calcium carbonate precipitation
at the surface membrane and at the underlying cell wall membrane of
the thermophilic soil bacterium Geobacillus stearothermophilus DSM 13240 have been revealed by high-resolution transmission electron
microscopy and atomic force microscopy. In this Gram-positive bacterium,
nanopores in the surface layer (S-layer) and in the supporting cell
wall polymers are nucleation sites for metastable calcium carbonate
polymorphs and polyamorphs. In order to observe the different metastable
forms, various reaction times and a low reaction temperature (4 °C)
have been chosen. Calcium carbonate polymorphs nucleate in the confinement
of nanosized pores (⌀ 3–5 nm) of the S-layer. The hydrous
crystalline calcium carbonate (ikaite) is formed initially with [110]
as the favored growth direction. It transforms into the anhydrous
metastable vaterite by a solid-state transition. In a following reaction
step, calcite is precipitated, caused by dissolution of vaterite in
the aqueous solution. In the larger pores of the cell wall (⌀
20–50 nm), hydrated amorphous calcium carbonate is grown, which
transforms into metastable monohydrocalcite, aragonite, or calcite.
Due to the sequence of reaction steps via various metastable phases,
the bacteria gain time for chipping the partially mineralized S-layer,
and forming a fresh S-layer (characteristic growth time about 20 min).
Thus, the bacteria can survive in solutions with high calcium carbonate
supersaturation under the conditions of forced biomineralization.
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Affiliation(s)
- Paul Simon
- Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Straße 40, 01187 Dresden, Germany
| | - Wolfgang Pompe
- Institute of Materials Science, Technische Universität Dresden, Helmholtzstraße 7, 01069 Dresden, Germany
| | - Denise Gruner
- Institute of Genetics, Technische Universität Dresden, Zellescher Weg 20b, 01217 Dresden, Germany.,Polymeric Microsystems, Technische Universität Dresden, Helmholtzstraße 100, 01069 Dresden, Germany
| | - Elena Sturm
- Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Straße 40, 01187 Dresden, Germany.,Physical Chemistry, University of Konstanz, POB 714, D-78457 Konstanz, Germany
| | - Kai Ostermann
- Institute of Genetics, Technische Universität Dresden, Zellescher Weg 20b, 01217 Dresden, Germany
| | - Sabine Matys
- Helmholtz Institute Freiberg for Resource Technology, Helmholtz-Zentrum Dresden-Rossendorf, Bautzener Landstraße 400, 01328 Dresden, Germany
| | - Manja Vogel
- Helmholtz Institute Freiberg for Resource Technology, Helmholtz-Zentrum Dresden-Rossendorf, Bautzener Landstraße 400, 01328 Dresden, Germany
| | - Gerhard Rödel
- Institute of Genetics, Technische Universität Dresden, Zellescher Weg 20b, 01217 Dresden, Germany
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Simon P, Pompe W, Bobeth M, Worch H, Kniep R, Formanek P, Hild A, Wenisch S, Sturm E. Podosome-Driven Defect Development in Lamellar Bone under the Conditions of Senile Osteoporosis Observed at the Nanometer Scale. ACS Biomater Sci Eng 2021; 7:2255-2267. [PMID: 33938726 PMCID: PMC8290401 DOI: 10.1021/acsbiomaterials.0c01493] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The degradation mechanism of human trabecular bone harvested from the central part of the femoral head of a patient with a fragility fracture of the femoral neck under conditions of senile osteoporosis was investigated by high-resolution electron microscopy. As evidenced by light microscopy, there is a disturbance of bone metabolism leading to severe and irreparable damages to the bone structure. These defects are evoked by osteoclasts and thus podosome activity. Podosomes create typical pit marks and holes of about 300-400 nm in diameter on the bone surface. Detailed analysis of the stress field caused by the podosomes in the extracellular bone matrix was performed. The calculations yielded maximum stress in the range of few megapascals resulting in formation of microcracks around the podosomes. Disintegration of hydroxyapatite and free lying collagen fibrils were observed at the edges of the plywood structure of the bone lamella. At the ultimate state, the disintegration of the mineralized collagen fibrils to a gelatinous matrix comes along with a delamination of the apatite nanoplatelets resulting in a brittle, porous bone structure. The nanoplatelets aggregate to big hydroxyapatite plates with a size of up to 10 x 20 μm2. The enhanced plate growth can be explained by the interaction of two mechanisms in the ruffled border zone: the accumulation of delaminated hydroxyapatite nanoplatelets near clusters of podosomes and the accelerated nucleation and random growth of HAP nanoplatelets due to a nonsufficient concentration of process-directing carboxylated osteocalcin cOC.
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Affiliation(s)
- Paul Simon
- Max-Planck-Institut für Chemische Physik fester Stoffe, Nöthnitzer Str. 40, 01187 Dresden, Germany
| | - Wolfgang Pompe
- Technical University of Dresden, Institute of Materials Science, 01069 Dresden, Germany
| | - Manfred Bobeth
- Technical University of Dresden, Institute of Materials Science, 01069 Dresden, Germany
| | - Hartmut Worch
- Technical University of Dresden, Institute of Materials Science, 01069 Dresden, Germany
| | - Rüdiger Kniep
- Max-Planck-Institut für Chemische Physik fester Stoffe, Nöthnitzer Str. 40, 01187 Dresden, Germany
| | - Petr Formanek
- Leibniz-Institut für Polymerforschung Dresden e.V., Hohe Straße 6, 01069 Dresden, Germany
| | - Anne Hild
- Clinical Anatomy, Clinic of Small Animals, Justus-Liebig-University, 35385 Giessen, Germany
| | - Sabine Wenisch
- Clinical Anatomy, Clinic of Small Animals, Justus-Liebig-University, 35385 Giessen, Germany
| | - Elena Sturm
- Max-Planck-Institut für Chemische Physik fester Stoffe, Nöthnitzer Str. 40, 01187 Dresden, Germany.,University of Konstanz, Physical Chemistry, POB 714, D-78457 Konstanz, Germany
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Simon P, Grüner D, Worch H, Pompe W, Lichte H, El Khassawna T, Heiss C, Wenisch S, Kniep R. First evidence of octacalcium phosphate@osteocalcin nanocomplex as skeletal bone component directing collagen triple-helix nanofibril mineralization. Sci Rep 2018; 8:13696. [PMID: 30209287 PMCID: PMC6135843 DOI: 10.1038/s41598-018-31983-5] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2018] [Accepted: 08/29/2018] [Indexed: 01/27/2023] Open
Abstract
Tibia trabeculae and vertebrae of rats as well as human femur were investigated by high-resolution TEM at the atomic scale in order to reveal snapshots of the morphogenetic processes of local bone ultrastructure formation. By taking into account reflections of hydroxyapatite for Fourier filtering the appearance of individual alpha-chains within the triple-helix clearly shows that bone bears the feature of an intergrowth composite structure extending from the atomic to the nanoscale, thus representing a molecular composite of collagen and apatite. Careful Fourier analysis reveals that the non-collagenous protein osteocalcin is present directly combined with octacalcium phosphate. Besides single spherical specimen of about 2 nm in diameter, osteocalcin is spread between and over collagen fibrils and is often observed as pearl necklace strings. In high-resolution TEM, the three binding sites of the γ-carboxylated glutamic acid groups of the mineralized osteocalcin were successfully imaged, which provide the chemical binding to octacalcium phosphate. Osteocalcin is attached to the collagen structure and interacts with the Ca-sites on the (100) dominated hydroxyapatite platelets with Ca-Ca distances of about 9.5 Å. Thus, osteocalcin takes on the functions of Ca-ion transport and suppression of hydroxyapatite expansion.
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Affiliation(s)
- Paul Simon
- Max-Planck-Institut für Chemische Physik fester Stoffe, Nöthnitzer Str. 40, 01187, Dresden, Germany.
| | - Daniel Grüner
- Forschungszentrum Jülich GmbH, Institute of Energy and Climate Research, IEK-2, 52425, Jülich, Germany
| | - Hartmut Worch
- Institute of Materials Science, Technical University of Dresden, Helmholtzstr. 7, 01069, Dresden, Germany
| | - Wolfgang Pompe
- Institute of Materials Science, Technical University of Dresden, Helmholtzstr. 7, 01069, Dresden, Germany
| | - Hannes Lichte
- Institute of Structure Physics, Technical University of Dresden, Zum Triebenberg 50, 01328, Dresden Zaschendorf, Germany
| | - Thaqif El Khassawna
- Experimental Trauma Surgery, Faculty of Medicine, Justus-Liebig University of Giessen, Aulweg 128, Giessen, 35392, Germany
| | - Christian Heiss
- Experimental Trauma Surgery, Faculty of Medicine, Justus-Liebig University of Giessen, Aulweg 128, Giessen, 35392, Germany
- Department of Trauma, Hand and Reconstructive Surgery, University Hospital of Giessen-Marburg, Giessen, Germany
| | - Sabine Wenisch
- Clinic of Small animals, c/o Institute of Veterinary Anatomy, Justus-Liebig University of Giessen, Giessen, Germany
| | - Rüdiger Kniep
- Max-Planck-Institut für Chemische Physik fester Stoffe, Nöthnitzer Str. 40, 01187, Dresden, Germany
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Mkandawire MM, Lakatos M, Springer A, Clemens A, Appelhans D, Krause-Buchholz U, Pompe W, Rödel G, Mkandawire M. Induction of apoptosis in human cancer cells by targeting mitochondria with gold nanoparticles. Nanoscale 2015; 7:10634-10640. [PMID: 26022234 DOI: 10.1039/c5nr01483b] [Citation(s) in RCA: 56] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
A major challenge in designing cancer therapies is the induction of cancer cell apoptosis, although activation of intrinsic apoptotic pathways by targeting gold nanoparticles to mitochondria is promising. We report an in vitro procedure targeting mitochondria with conjugated gold nanoparticles and investigating effects on apoptosis induction in the human breast cancer cell line Jimt-1. Gold nanoparticles were conjugated to a variant of turbo green fluorescent protein (mitoTGFP) harbouring an amino-terminal mitochondrial localization signal. Au nanoparticle conjugates were further complexed with cationic maltotriose-modified poly(propylene imine) third generation dendrimers. Fluorescence and transmission electron microscopy revealed that Au nanoparticle conjugates were directed to mitochondria upon transfection, causing partial rupture of the outer mitochondrial membrane, triggering cell death. The ability to target Au nanoparticles into mitochondria of breast cancer cells and induce apoptosis reveals an alternative application of Au nanoparticles in photothermal therapy of cancer.
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Affiliation(s)
- M M Mkandawire
- Encyt Technologies Inc., 201 Churchill Drive, Membertou, NS, Canada B1S OH1.
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Pompe W, Worch H, Habraken WJEM, Simon P, Kniep R, Ehrlich H, Paufler P. Octacalcium phosphate - a metastable mineral phase controls the evolution of scaffold forming proteins. J Mater Chem B 2015; 3:5318-5329. [PMID: 32262608 DOI: 10.1039/c5tb00673b] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
The molecular structure of collagen type 1 can be understood as the result of evolutionary selection in the process of formation of calcium phosphate based biocomposites acting as load bearing components in living organisms. The evolutionary selection fulfills the principle of 'survival of the fittest' in a particular biological environment. Disk-like post-nucleation complexes of Ca2(HPO4)3 2- organized in ribbon-like assemblies in the metastable octacalcium phosphate (OCP) phase, and Ca3 triangles in the stable HAP phase had formed the crystallographic motifs in this selection process. The rotational as well as the translational symmetry of the major tropocollagen (TC) helix agree nearly perfectly with the corresponding symmetries of the OCP structure. The sequence of (Gly-X-Y) motifs of the three α chains constituting the TC molecule enables an optimized structural fit for the nucleation of Ca3 triangles, the directed growth of nanostructured OCP, and the subsequent formation of hydroxyapatite (HAP) in collagen macrofibrils by a topotaxial transition. The known connection between genetic defects of collagen type 1 and Osteogenesis imperfecta should motivate the search for similar dependences of other bone diseases on a disturbed molecular structure of collagen on the genetic scale.
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Affiliation(s)
- Wolfgang Pompe
- Institute of Materials Science, Technical University Dresden, D-01062 Dresden, Germany.
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Lakatos M, Matys S, Raff J, Pompe W. Colorimetric As (V) detection based on S-layer functionalized gold nanoparticles. Talanta 2015; 144:241-6. [PMID: 26452816 DOI: 10.1016/j.talanta.2015.05.082] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2015] [Revised: 05/27/2015] [Accepted: 05/30/2015] [Indexed: 11/29/2022]
Abstract
Herein, we present simple and rapid colorimetric and UV/VIS spectroscopic methods for detecting anionic arsenic (V) complexes in aqueous media. The methods exploit the aggregation of S-layer-functionalized spherical gold nanoparticles of sizes between 20 and 50 nm in the presence of arsenic species. The gold nanoparticles were functionalized with oligomers of the S-layer protein of Lysinibacillus sphaericus JG-A12. The aggregation of the nanoparticles results in a color change from burgundy-red for widely dispersed nanoparticles to blue for aggregated nanoparticles. A detailed signal analysis was achieved by measuring the shift of the particle plasmon resonance signal with UV/VIS spectroscopy. To further improve signal sensitivity, the influence of larger nanoparticles was tested. In the case of 50 nm gold nanoparticles, a concentration of the anionic arsenic (V) complex lower than 24 ppb was detectable.
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Affiliation(s)
- Mathias Lakatos
- Dresden University of Technology, Institute of Materials Science, Max Bergmann Center of Biomaterials, Budapester Strasse 27, 01069 Dresden, Germany.
| | - Sabine Matys
- Helmholtz-Zentrum Dresden-Rossendorf, Helmholtz Institute Freiberg for Resource Technology, Halsbruecker Strasse 34, 09599 Freiberg, Germany
| | - Johannes Raff
- Helmholtz-Zentrum Dresden-Rossendorf, Helmholtz Institute Freiberg for Resource Technology, Halsbruecker Strasse 34, 09599 Freiberg, Germany; Helmholtz-Zentrum Dresden-Rossendorf, Institute of Resource Ecology, Bautzner Landstraße 400, 01328 Dresden, Germany
| | - Wolfgang Pompe
- Dresden University of Technology, Institute of Materials Science, Max Bergmann Center of Biomaterials, Budapester Strasse 27, 01069 Dresden, Germany
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Pompe W. Materials Science of DNA. Edited by J.-I. Jin and J. Grote. Pp. 326. Boca Raton: CRC Press, Taylor & Francis Group, 2012. Price (hardcover) GBP 76.99. ISBN 978-1-398-2741-3. J Appl Crystallogr 2012. [DOI: 10.1107/s0021889812014434] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/03/2023] Open
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Pompe T, Kaufmann M, Kasimir M, Johne S, Glorius S, Renner L, Bobeth M, Pompe W, Werner C. Friction-controlled traction force in cell adhesion. Biophys J 2012; 101:1863-70. [PMID: 22004739 DOI: 10.1016/j.bpj.2011.08.027] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2011] [Revised: 08/11/2011] [Accepted: 08/12/2011] [Indexed: 01/29/2023] Open
Abstract
The force balance between the extracellular microenvironment and the intracellular cytoskeleton controls the cell fate. We report a new (to our knowledge) mechanism of receptor force control in cell adhesion originating from friction between cell adhesion ligands and the supporting substrate. Adherent human endothelial cells have been studied experimentally on polymer substrates noncovalently coated with fluorescent-labeled fibronectin (FN). The cellular traction force correlated with the mobility of FN during cell-driven FN fibrillogenesis. The experimental findings have been explained within a mechanistic two-dimensional model of the load transfer at focal adhesion sites. Myosin motor activity in conjunction with sliding of FN ligands noncovalently coupled to the surface of the polymer substrates is shown to result in a controlled traction force of adherent cells. We conclude that the friction of adhesion ligands on the supporting substrate is important for mechanotransduction and cell development of adherent cells in vitro and in vivo.
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Affiliation(s)
- Tilo Pompe
- Universität Leipzig, Institute of Biochemistry, Leipzig, Germany.
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Bobeth M, Blecha A, Blüher A, Mertig M, Korkmaz N, Ostermann K, Rödel G, Pompe W. Formation of tubes during self-assembly of bacterial surface layers. Langmuir 2011; 27:15102-15111. [PMID: 22029537 DOI: 10.1021/la203430q] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Based on experimental studies on tube formation during self-assembly of bacterial surface (S)-layers, a mechanistic model for describing the underlying basic mechanisms is proposed and the effect of process parameters on growth velocity and tube radius is investigated. The S-layer is modeled as a curved sheet with discrete binding sites for the association of monomers distributed along the S-layer edges. Reported changes of the tube radius owing to genetic protein modifications are explained within the framework of continuum mechanics. S-layer growth velocity and shape development are analyzed by Monte Carlo simulation in their dependence on the attachment and detachment frequencies of monomers at the S-layer. For curved S-layer patches, a criterion for the formation of S-layer tubes is derived. Accordingly, tubes can form only within a certain range of the initial monomer concentration. Furthermore, the effect of calcium ion concentration on tube formation is discussed, including recent experimental findings on the calcium effect.
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Affiliation(s)
- Manfred Bobeth
- Institut für Werkstoffwissenschaft and Max-Bergmann-Zentrum für Biomaterialien, Technische Universität Dresden, 01062 Dresden, Germany
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Pannier A, Mkandawire M, Soltmann U, Pompe W, Böttcher H. Biological activity and mechanical stability of sol–gel-based biofilters using the freeze-gelation technique for immobilization of Rhodococcus ruber. Appl Microbiol Biotechnol 2011; 93:1755-67. [DOI: 10.1007/s00253-011-3489-7] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2011] [Revised: 05/19/2011] [Accepted: 07/14/2011] [Indexed: 10/17/2022]
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Abstract
λ-DNA as well as plasmids can be successfully deposited by molecular combing on hydrophobic surfaces, for pH values ranging from 4 to 10. On polydimethylsiloxane (PDMS) substrates, the deposited DNA molecules are overstretched by about 60-100%. There is a significant influence of sodium ions (NaCl) on the surface density of the deposited DNA, with a maximum near to 100 mM NaCl for a DNA solution (28 ng µl(-1)) at pH 8. The combing process can be described by a micromechanical model including: (i) the adsorption of free moving coiled DNA at the substrate; (ii) the stretching of the coiled DNA by the preceding meniscus; (iii) the relaxation of the deposited DNA to the final length. The sticky ends of λ-DNA cause an adhesion force in the range of about 400 pN which allows a stable overstretching of the DNA by the preceding meniscus. The exposing of hidden hydrophobic bonds of the overstretched DNA leads to a stable deposition on the hydrophobic substrate. The pH-dependent density of deposited DNA as well as the observed influence of sodium ions can be explained by their screening of the negatively charged DNA backbone and sticky ends, respectively. The final DNA length can be derived from a balance of the stored elastic energy of the overstretched molecules and the energy of adhesion.
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Affiliation(s)
- Annegret Benke
- Institut für Werkstoffwissenschaft and Max-Bergmann-Zentrum für Biomaterialien, Technische Universität Dresden, Dresden, Germany.
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Gutmann E, Benke A, Gerth K, Mehner E, Klein C, Krause-Buchholz U, Pompe W, Meyer DC. Impact of pyroelectric LiNbO 3and LiTaO 3on water, organic dyes and E. coli. Acta Crystallogr A 2010. [DOI: 10.1107/s0108767310096388] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
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Ranjan N, Mertig M, Cuniberti G, Pompe W. Dielectrophoretic growth of metallic nanowires and microwires: theory and experiments. Langmuir 2010; 26:552-559. [PMID: 19924880 DOI: 10.1021/la902026e] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Dielectrophoresis-assisted growth of metallic nanowires from an aqueous salt solution has been previously reported, but so far there has been no clear understanding of the process leading to such a bottom-up assembly. The present work, based on a series of experiments to grow metallic nano- and microwires by dielectrophoresis, provides a general theoretical description of the growth of such wires from an aqueous salt solution. Palladium nanowires and silver microwires have been grown between gold electrodes from their aqueous salt solution via dielectrophoresis. Silver microwire growth has been observed in situ using light microscopy. From these experiments, a basic model of dielectrophoresis-driven wire growth is developed. This model explains the dependence of the growth on the frequency and the local field enhancement at the electrode asperities. Such a process proves instrumental in the growth of metallic nanowires with controlled morphology and site specificity between the electrodes.
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Affiliation(s)
- Nitesh Ranjan
- Institute for Materials Science and Max Bergmann Center of Biomaterials, Dresden University of Technology, 01062 Dresden, Germany.
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Mkandawire M, Pohl A, Gubarevich T, Lapina V, Appelhans D, Rödel G, Pompe W, Schreiber J, Opitz J. Selective targeting of green fluorescent nanodiamond conjugates to mitochondria in HeLa cells. J Biophotonics 2009; 2:596-606. [PMID: 19504515 DOI: 10.1002/jbio.200910002] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Fluorescent cellular biomarkers play a prominent role in biosciences. Most of the available biomarkers have some drawbacks due to either physical and optical or cytotoxic properties. In view of this, we investigated the potential of green fluorescent nanodiamonds as biomarkers in living cells. Nanodiamonds were functionalized by attaching antibodies that target intracellular structures such as actin filaments and mitochondria. Then, the nanodiamond conjugates were transfected into HeLa cells. Transfections were mediated by 4(th)-generation dendrimers, cationic liposomes and protamine sulfate. Using fluorescence microscopy, we confirmed successful transfections of the nanodiamonds into HeLa cells. Nanodiamond fluorescence could be easily differentiated from cellular autofluorescence. Furthermore, nanodiamonds could be targeted selectively to intracellular structures. Therefore, nanodiamonds are a promising tool for intracellular assays.
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Affiliation(s)
- Msaukiranji Mkandawire
- Institute of Genetics, University of Technology Dresden, Zellescher Weg 20b, 01217 Dresden, Germany.
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Bastian S, Busch W, Kühnel D, Springer A, Meißner T, Holke R, Scholz S, Iwe M, Pompe W, Gelinsky M, Potthoff A, Richter V, Ikonomidou C, Schirmer K. Toxicity of tungsten carbide and cobalt-doped tungsten carbide nanoparticles in mammalian cells in vitro. Environ Health Perspect 2009; 117:530-6. [PMID: 19440490 PMCID: PMC2679595 DOI: 10.1289/ehp.0800121] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/22/2008] [Accepted: 12/01/2008] [Indexed: 05/22/2023]
Abstract
BACKGROUND Tungsten carbide nanoparticles are being explored for their use in the manufacture of hard metals. To develop nanoparticles for broad applications, potential risks to human health and the environment should be evaluated and taken into consideration. OBJECTIVE We aimed to assess the toxicity of well-characterized tungsten carbide (WC) and cobalt-doped tungsten carbide (WC-Co) nanoparticle suspensions in an array of mammalian cells. METHODS We examined acute toxicity of WC and of WC-Co (10% weight content Co) nanoparticles in different human cell lines (lung, skin, and colon) as well as in rat neuronal and glial cells (i.e., primary neuronal and astroglial cultures and the oligodendrocyte precursor cell line OLN-93). Furthermore, using electron microscopy, we assessed whether nanoparticles can be taken up by living cells. We chose these in vitro systems in order to evaluate for potential toxicity of the nanoparticles in different mammalian organs (i.e., lung, skin, intestine, and brain). RESULTS Chemical-physical characterization confirmed that WC as well as WC-Co nanoparticles with a mean particle size of 145 nm form stable suspensions in serum-containing cell culture media. WC nanoparticles were not acutely toxic to the studied cell lines. However, cytotoxicity became apparent when particles were doped with Co. The most sensitive were astrocytes and colon epithelial cells. Cytotoxicity of WC-Co nanoparticles was higher than expected based on the ionic Co content of the particles. Analysis by electron microscopy demonstrated presence of WC nanoparticles within mammalian cells. CONCLUSIONS Our findings demonstrate that doping of WC nanoparticles with Co markedly increases their cytotoxic effect and that the presence of WC-Co in particulate form is essential to elicit this combinatorial effect.
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Affiliation(s)
- Susanne Bastian
- Department of Pediatric Neurology, University Children’s Hospital Carl Gustav Carus, University of Technology Dresden, Dresden, Germany
| | - Wibke Busch
- Department of Cell Toxicology, UFZ-Helmholtz Centre for Environmental Research, Leipzig, Germany
| | - Dana Kühnel
- Department of Cell Toxicology, UFZ-Helmholtz Centre for Environmental Research, Leipzig, Germany
| | - Armin Springer
- Max Bergmann Center of Biomaterials, Institute of Materials Science, University of Technology Dresden, Dresden, Germany
| | - Tobias Meißner
- Fraunhofer Institute for Ceramic Technologies and Systems, Dresden, Germany
| | - Roland Holke
- Fraunhofer Institute for Ceramic Technologies and Systems, Dresden, Germany
| | - Stefan Scholz
- Department of Cell Toxicology, UFZ-Helmholtz Centre for Environmental Research, Leipzig, Germany
| | - Maria Iwe
- Department of Pediatric Neurology, University Children’s Hospital Carl Gustav Carus, University of Technology Dresden, Dresden, Germany
| | - Wolfgang Pompe
- Max Bergmann Center of Biomaterials, Institute of Materials Science, University of Technology Dresden, Dresden, Germany
| | - Michael Gelinsky
- Max Bergmann Center of Biomaterials, Institute of Materials Science, University of Technology Dresden, Dresden, Germany
| | - Annegret Potthoff
- Fraunhofer Institute for Ceramic Technologies and Systems, Dresden, Germany
| | - Volkmar Richter
- Fraunhofer Institute for Ceramic Technologies and Systems, Dresden, Germany
| | - Chrysanthy Ikonomidou
- Department of Pediatric Neurology, University Children’s Hospital Carl Gustav Carus, University of Technology Dresden, Dresden, Germany
| | - Kristin Schirmer
- Department of Cell Toxicology, UFZ-Helmholtz Centre for Environmental Research, Leipzig, Germany
- Eawag, Swiss Federal Institute of Aquatic Science and Technology, Dübendorf, Switzerland
- Address correspondence to K. Schirmer, Environmental Toxicology, Eawag, Überlandstrasse 133, 8600 Dübendorf, Switzerland. Telephone: 41-0-44-823-5266., Fax: 41-0-44-823-5311., E-mail:
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Stoecker H, Levin A, Gutmann E, Weissbach T, Leisegang T, Ritter S, Elschner C, Bobeth M, Pompe W, Meyer D. Reversible structural changes by electrostatic fields in strontium titanate at room temperature. Acta Crystallogr A 2008. [DOI: 10.1107/s010876730808505x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
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Yokoyama A, Gelinsky M, Kawasaki T, Kohgo T, König U, Pompe W, Watari F. Biomimetic porous scaffolds with high elasticity made from mineralized collagen--an animal study. J Biomed Mater Res B Appl Biomater 2008; 75:464-72. [PMID: 16044430 DOI: 10.1002/jbm.b.30331] [Citation(s) in RCA: 72] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Histological investigations of a new hydroxyapatite-collagen composite material were carried out to evaluate its possible suitability as a bone substitute. The three-dimensional scaffolds made from biomimetically mineralized collagen exhibit an interconnecting pore structure and elastic mechanical properties. They were implanted into the subcutaneous tissue and bone defects made in the femur of rats and harvested with the surrounding tissue at 1, 2, 4, 8, and 12 weeks after surgery. The materials implanted in the subcutaneous tissue were covered by fibrous connective tissue with a slight inflammatory response, and many foreign-body giant cells were observed on the surface of the scaffolds. Most of the material implanted in the subcutaneous tissue was resorbed at 8 weeks by phagocytosis. In the bone defects, new bone formation was observed on the surface of the material at 1 week. New bone increased with time, and osteoclasts were seen on the surface of the scaffolds at 2 weeks. Resorption and replacement by new bone of many parts of the materials implanted in the femur were observed by 12 weeks. These responses occurred faster than those of other hydroxyapatite-collagen composites. The results suggested that the new biomimetically mineralized collagen scaffolds were suitable as an implant material for bone-tissue reconstruction.
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Affiliation(s)
- Atsuro Yokoyama
- Graduate School of Dental Medicine, Hokkaido University, Kita 13, Nishi 7, Kita-Ku, Sapporo 060-8586, Japan.
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Mai R, Reinstorf A, Pilling E, Hlawitschka M, Jung R, Gelinsky M, Schneider M, Loukota R, Pompe W, Eckelt U, Stadlinger B. Histologic study of incorporation and resorption of a bone cement–collagen composite: an in vivo study in the minipig. ACTA ACUST UNITED AC 2008; 105:e9-14. [DOI: 10.1016/j.tripleo.2007.09.016] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2005] [Revised: 09/03/2007] [Accepted: 09/24/2007] [Indexed: 10/22/2022]
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Bernhardt A, Lode A, Boxberger S, Pompe W, Gelinsky M. Mineralised collagen--an artificial, extracellular bone matrix--improves osteogenic differentiation of bone marrow stromal cells. J Mater Sci Mater Med 2008; 19:269-75. [PMID: 17597360 DOI: 10.1007/s10856-006-0059-0] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/24/2006] [Accepted: 11/29/2006] [Indexed: 05/16/2023]
Abstract
In the field of bone tissue engineering there is a high demand on bone graft materials which promote bone formation. By combination of collagen type I with nanocrystalline hydroxyapatite (HA) we generated a resorbable material which structure and composition is close to those of the extracellular bone matrix. This nanocomposite material was produced in a biomimetic process in which collagen fibril assembly and mineralisation with hydroxyapatite occur simultaneously. In this study the proliferation and osteogenic differentiation of human bone marrow-derived stromal cells (hBMSC) on membranes of biomimetically mineralised collagen type I was investigated. To this end, we optimised biochemical assays for determination of cell number and alkaline phosphatase activity corresponding to the special properties of this biomaterial. For cell experiments hBMSC were seeded on the mineralised collagen membranes and cultivated over 35 days, both in static and perfusion culture, in the presence and absence of dexamethasone, beta-glycerophosphate and ascorbate. Compared to cells grown on tissue culture polystyrene we found attenuated proliferation rates, but markedly increased activity of alkaline phosphatase on the mineralised collagen indicating its promoting effect on the osteogenic differentiation of hBMSC. Therefore this bone-like material may act as a suitable artificial extracellular matrix for bone tissue engineering. Perfusion of the 2D cell matrix constructs with cell culture medium did not improve proliferation and osteogenic differentiation of the hBMSC.
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Affiliation(s)
- Anne Bernhardt
- Max Bergmann Center of Biomaterials, Institute of Materials Science, Technische Universität Dresden, Budapester-Str. 27, 01069 Dresden, Germany.
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Lode A, Wolf-Brandstetter C, Reinstorf A, Bernhardt A, König U, Pompe W, Gelinsky M. Calcium phosphate bone cements, functionalized with VEGF: release kinetics and biological activity. J Biomed Mater Res A 2007; 81:474-83. [PMID: 17133509 DOI: 10.1002/jbm.a.31024] [Citation(s) in RCA: 70] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Calcium phosphate bone cements are of great interest for bone replacement since the nanocrystalline structure allows their remodelling into native bone tissue. A strategy to accelerate vascularization of the implant region is the functionalization with vascular endothelial growth factor (VEGF), which is known to mediate angiogenesis in vivo. In this study, the release of recombinant human VEGF (rhVEGF(165)) following physical adsorption to Biocement D (BioD) and several modifications were investigated. Our data demonstrate a high VEGF binding capacity of BioD and a sustained release with a moderate initial burst. A proliferation assay using endothelial cells revealed maintenance of biological activity of VEGF after release from BioD. Release behavior of BioD was not improved by modification with mineralized collagen type I, as well as with a combination of mineralized collagen with O-phospho-L-serine and sodium citrate, respectively. In contrast, a positive impact of these modifications on the activity of released VEGF was observed; in case of the phosphoserine- and sodium citrate-modified cements, the biological efficacy of released VEGF was even higher than that of nonreleased control VEGF. We conclude that the bone implant material BioD and, especially, the phosphoserine modification may support activation of angiogenesis by delivery of VEGF in a local and sustained manner.
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Affiliation(s)
- A Lode
- Institute of Materials Science, Max Bergmann Center of Biomaterials, Technische Universität Dresden, D-01069 Dresden, Germany.
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Pompe W. Nanodevices for the Life Sciences. Edited by Challa S. S. R. Kumar. Nanotechnologies for Life Sciences. Volume 4. Weinheim: Wiley-VCH Verl. GmbH Co. KGaA, 1st Edition 2006. Pp. 469. Price 139 EUR/220 SFR. ISBN-10: 3-527-31384-2. ISBN-13: 978-3-527-31384-6. Acta Crystallogr Sect F Struct Biol Cryst Commun 2007. [PMCID: PMC2335146 DOI: 10.1107/s1744309107023652] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Pompe W. Nanomaterials – Toxicity, Health and Environmental Issues. By Challa S.S.R. Kumar (Ed.). Biotechnol J 2007. [DOI: 10.1002/biot.200790079] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Schneiders W, Reinstorf A, Pompe W, Grass R, Biewener A, Holch M, Zwipp H, Rammelt S. Effect of modification of hydroxyapatite/collagen composites with sodium citrate, phosphoserine, phosphoserine/RGD-peptide and calcium carbonate on bone remodelling. Bone 2007; 40:1048-59. [PMID: 17223400 DOI: 10.1016/j.bone.2006.11.019] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/11/2006] [Revised: 11/18/2006] [Accepted: 11/22/2006] [Indexed: 11/26/2022]
Abstract
This study describes the early interface reaction of cancellous bone to a nanocrystalline hydroxyapatite cement containing type I collagen (HA/Coll) and its modifications with sodium citrate (CI), calcium carbonate (CA), phosphoserine (P) and phosphoserine plus RGD-peptide (RGD). Cylindrical implants of HA/Coll and its modifications were inserted into the tibia of Wistar rats. We analysed 6 specimens per group at days 2, 4, 7, 14 and 28. CI, P and RGD modifications showed improved material properties (finer microstructure and higher compressive strength) compared to CA and HA/Coll implants. The powder X-ray diffraction (XRD) showed that the addition of P and CI led to an increase of alpha-TCP peaks while the diffraction patterns of the non-modified cement (HA/Coll) were quite similar with that of natural bone. All of the implants healed without adverse reactions. A significantly higher number of TRAP-positive osteoclasts were observed around CI, RGD and P on day 7 compared to CA and HA/Coll. Around CI, P and RGD a significantly delayed increase of ED1-positive mononuclear cells was detected. The amount of direct bone contact after 28 days was significantly higher around CI, P and RGD compared to CA and HA/Coll implants. The addition of CI, P and RGD appears to enhance bone remodelling at the early stages of bone healing, leading to increased bone formation around HA/Coll composite cements.
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Affiliation(s)
- Wolfgang Schneiders
- Department of Trauma and Reconstructive Surgery, University Hospital Carl Gustav Carus, Fetscherstrasse 74, 01307 Dresden, Germany.
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Freudenberg U, Behrens SH, Welzel PB, Müller M, Grimmer M, Salchert K, Taeger T, Schmidt K, Pompe W, Werner C. Electrostatic interactions modulate the conformation of collagen I. Biophys J 2007; 92:2108-19. [PMID: 17208984 PMCID: PMC1861768 DOI: 10.1529/biophysj.106.094284] [Citation(s) in RCA: 78] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
The pH- and electrolyte-dependent charging of collagen I fibrils was analyzed by streaming potential/streaming current experiments using the Microslit Electrokinetic Setup. Differential scanning calorimetry and circular dichroism spectroscopy were applied in similar electrolyte solutions to characterize the influence of electrostatic interactions on the conformational stability of the protein. The acid base behavior of collagen I was found to be strongly influenced by the ionic strength in KCl as well as in CaCl(2) solutions. An increase of the ionic strength with KCl from 10(-4) M to 10(-2) M shifts the isoelectric point (IEP) of the protein from pH 7.5 to 5.3. However, a similar increase of the ionic strength in CaCl(2) solutions shifts the IEP from 7.5 to above pH 9. Enhanced thermal stability with increasing ionic strength was observed by differential scanning calorimetry in both electrolyte systems. In line with this, circular dichroism spectroscopy results show an increase of the helicity with increasing ionic strength. Better screening of charged residues and the formation of salt bridges are assumed to cause the stabilization of collagen I with increasing ionic strength in both electrolyte systems. Preferential adsorption of hydroxide ions onto intrinsically uncharged sites in KCl solutions and calcium binding to negatively charged carboxylic acid moieties in CaCl(2) solutions are concluded to shift the IEP and influence the conformational stability of the protein.
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Affiliation(s)
- Uwe Freudenberg
- Leibniz Institute of Polymer Research Dresden, Max Bergmann Center of Biomaterials Dresden, Dresden, Germany
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Dinu CZ, Opitz J, Pompe W, Howard J, Mertig M, Diez S. Parallel manipulation of bifunctional DNA molecules on structured surfaces using kinesin-driven microtubules. Small 2006; 2:1090-8. [PMID: 17193173 DOI: 10.1002/smll.200600112] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
We have developed a technique to manipulate bifunctional DNA molecules: One end is thiolated to bind to a patterned gold surface and the other end is biotinylated to bind to a microtubule gliding over a kinesin-coated surface. We found that DNA molecules can be stretched and overstretched between the gold pads and the motile microtubules, and that they can form dynamic networks. This serves as a proof-of-principle that biological machineries can be used in vitro to accomplish the parallel formation of structured DNA templates that will have applications in biophysics and nanoelectronics.
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Affiliation(s)
- Cerasela Zoica Dinu
- Max Planck Institute of Molecular Cell Biology and Genetics, 01307 Dresden, Germany
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Abstract
The catalytic oxidation activity of platinum particles in automobile catalysts is thought to originate from the presence of highly reactive superficial oxide phases which form under oxygen-rich reaction conditions. Here we study the thermodynamic stability of platinum oxide surfaces and thin films and their reactivities toward oxidation of carbon compounds by means of first-principles atomistic thermodynamics calculations and molecular dynamics simulations based on density functional theory. On the Pt(111) surface the most stable superficial oxide phase is found to be a thin layer of alpha-PtO2, which appears not to be reactive toward either methane dissociation or carbon monoxide oxidation. A PtO-like structure is most stable on the Pt(100) surface at oxygen coverages of one monolayer, while the formation of a coherent and stress-free Pt3O4 film is favored at higher coverages. Bulk Pt3O4 is found to be thermodynamically stable in a region around 900 K at atmospheric pressure. The computed net driving force for the dissociation of methane on the Pt3O4(100) surface is much larger than that on all other metallic and oxide surfaces investigated. Moreover, the enthalpy barrier for the adsorption of CO molecules on oxygen atoms of this surface is as low as 0.34 eV, and desorption of CO2 is observed to occur without any appreciable energy barrier in molecular dynamics simulations. These results, combined, indicate a high catalytic oxidation activity of Pt3O4 phases that can be relevant in the contexts of Pt-based automobile catalysts and gas sensors.
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Affiliation(s)
- Nicola Seriani
- Institut für Werkstoffwissenschaft, Technische Universität Dresden, Hallwachsstrasse 3, 01069 Dresden, Germany.
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Pompe W. Biofunctionalization of Nanomaterials. Edited by Challa Kumar. Nanotechnologies for Life Sciences. Volume 1. Pp. xx+366. Weinheim: Wiley–VCH Verlag GmbH Co. KGaA, 2005. Price (hardcover) 139 Euro/220 SFR. ISBN: 3-527-31381-8. Acta Crystallogr D Biol Cryst 2006. [DOI: 10.1107/s0907444906008729] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Domaschke H, Gelinsky M, Burmeister B, Fleig R, Hanke T, Reinstorf A, Pompe W, Rösen-Wolff A. In VitroOssification and Remodeling of Mineralized Collagen I Scaffolds. ACTA ACUST UNITED AC 2006; 12:949-58. [PMID: 16674306 DOI: 10.1089/ten.2006.12.949] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
A promising strategy of bone tissue engineering is to repair bone defects by implanting biodegradable scaffolds that can undergo remodeling and be replaced completely by autologous bone tissue. For this purpose, it is necessary to create scaffolds that can be degraded by osteoclasts and enable osteoblasts to build new mineralized bone matrix. In order to achieve this goal a new porous material has been developed using biomimetically mineralized collagen I. These scaffolds were co-cultured with osteoclast-like cells and osteoblasts in order to characterize the capacity of these cells to remodel the material in vitro. It was possible to show the development of biologically active osteoclast- like cells that were able to invade and degrade the scaffold. They degraded the scaffold by internalizing it as intracellular vesicles, thereby making room for osteoblasts to invade and build new bone matrix. In addition, it could be shown that osteoblasts proliferated, differentiated, and produced new mineralized extracellular matrix. Hence, it could be shown that co-culture of osteoclastlike cells and osteoblasts on biomimetically mineralized collagen I is a promising approach for bone tissue engineering. In addition, it can be applied to study the process of bone remodeling in vitro.
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Affiliation(s)
- Hagen Domaschke
- Department of Pediatrics, University Clinic Carl Gustav Carus, Dresden University of Technology, Dresden, Germany
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Rammelt S, Neumann M, Hanisch U, Reinstorf A, Pompe W, Zwipp H, Biewener A. Osteocalcin enhances bone remodeling around hydroxyapatite/collagen composites. J Biomed Mater Res A 2005; 73:284-94. [PMID: 15800855 DOI: 10.1002/jbm.a.30263] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The effect of osteocalcin (OC), an extracellular bone matrix protein, on bone healing around hydroxyapatite/collagen composites was investigated. Cylindrical nanocrystalline hydroxyapatite implants of 2.5-mm diameter containing 2.5% biomimetically mineralized collagen type I were inserted press-fit into the tibial head of adult Wistar rats. To one implant group, 10 mug/g OC was added. Six specimens per group were analyzed at 2, 7, 14, 28, and 56 days. After 14 days, newly formed woven bone had reached the implant surface of the OC implants whereas a broad fibrous interface could still be observed around controls. Woven bone was formed directly around both implant groups after 28 days and had been replaced partially by lamellar bone around the OC implants only. No significant differences in total bone contact were seen between both groups after 56 days. The higher number of phagocytosing cells and osteoclasts characterized immunohistochemically with ED1, cathepsin D, and tartate-resistant alkaline phosphatase around the OC implants at the early stages of bone healing suggests an earlier onset of bone remodeling. The earlier and increased expression of bone-specific matrix proteins and multifunctional adhesion proteins (osteopontin, bone sialoprotein, CD44) at the interface around the OC implants indicates that OC may accelerate bone formation and regeneration. This study supports the observations from in vitro studies that OC activates both osteoclasts and osteoblasts during early bone formation.
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Affiliation(s)
- Stefan Rammelt
- Department of Trauma and Reconstructive Surgery, University Hospital Carl Gustav Carus, Dresden, Germany.
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Monsees TK, Barth K, Tippelt S, Heidel K, Gorbunov A, Pompe W, Funk RHW. Effects of Different Titanium Alloys and Nanosize Surface Patterning on Adhesion, Differentiation, and Orientation of Osteoblast-Like Cells. Cells Tissues Organs 2005; 180:81-95. [PMID: 16113537 DOI: 10.1159/000086749] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/06/2005] [Indexed: 11/19/2022] Open
Abstract
To test nanosize surface patterning for application as implant material, a suitable titanium composition has to be found first. Therefore we investigated the effect of surface chemistry on attachment and differentiation of osteoblast-like cells on pure titanium prepared by pulsed laser deposition (TiPLD) and different Ti alloys (Ti6Al4V, TiNb30 and TiNb13Zr13). Early attachment (30 min) and alkaline phosphatase (ALP) activity (day 5) was found to be fastest and highest, respectively, in cells grown on TiPLD and Ti6Al4V. Osteoblasts seeded on TiPLD produced most osteopontin (day 10), whereas expression of this extracellular matrix protein was an order of magnitude lower on the TiNb30 surface. In contrast, expression of the corresponding receptor, CD44, was not influenced by surface chemistry. Thus, TiPLD was used for further experiments to explore the influence of surface nanostructures on osteoblast adhesion, differentiation and orientation. By laser-induced oxidation, we produced patterns of parallel Ti oxide lines with different widths (0.2-10 microm) and distances (2-20 and 1,000 microm), but a common height of only 12 nm. These structures did not influence ALP activity (days 5-9), but had a positive effect on cell alignment. Two days after plating, the majority of the focal contacts were placed on the oxide lines. The portion of larger focal adhesions bridging two lines was inversely related to the line distance (2-20 microm). In contrast, the portion of aligned cells did not depend on the line distance. On average, 43% of the cells orientated parallel towards the lines, whereas 34% orientated vertically. In the control pattern (1,000 microm line distance), cell distribution was completely at random. Because a significant surplus of the cells preferred a parallel alignment, the nanosize difference in height between Ti surface and oxide lines may be sufficient to orientate the cells by contact guiding. However, gradients in electrostatic potential and surface charge density at the Ti/Ti oxide interface may additionally influence focal contact formation and cell guidance.
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Affiliation(s)
- Thomas K Monsees
- Department of Anatomy, University of Technology, Dresden, Germany.
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Rümmeli MH, Borowiak-Palen E, Gemming T, Pichler T, Knupfer M, Kalbác M, Dunsch L, Jost O, Silva SRP, Pompe W, Büchner B. Novel catalysts, room temperature, and the importance of oxygen for the synthesis of single-walled carbon nanotubes. Nano Lett 2005; 5:1209-15. [PMID: 16178212 DOI: 10.1021/nl050692v] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
In this letter, we show for the first time the use of metal oxides as catalysts in the synthesis of single-walled carbon nanotubes (SWCNTs) using laser ablation. Further, SWCNTs have been synthesized at low temperature (down to room temperature), where their nucleation cannot be explained via fullerene nucleation. The data point to a nucleation mechanism previously not identified, that places a stable oxidized ring as the root cause for the growth of SWCNTs.
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Affiliation(s)
- Mark H Rümmeli
- Leibniz Institute for Solid State and Materials Research Dresden, IFW Dresden, P.O. Box 27016 D-01171 Dresden, Germany.
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Rammelt S, Schulze E, Witt M, Petsch E, Biewener A, Pompe W, Zwipp H. Collagen Type I Increases Bone Remodelling around Hydroxyapatite Implants in the Rat Tibia. Cells Tissues Organs 2005; 178:146-57. [PMID: 15655332 DOI: 10.1159/000082245] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/08/2004] [Indexed: 11/19/2022] Open
Abstract
The early interface reaction of cancellous bone to a nanocrystalline hydroxyapatite (HA) cement containing 3 wt% collagen type I (HA/Coll) with a setting under physiological temperature and pH was observed using immunohistochemical techniques. Pure HA served as a control. Cylinders with a diameter of 2 mm were implanted into the proximal tibia of 72 adult Wistar rats. Histological sections of 6 animals were prepared after 1, 2, 4, 6, 14 and 28 days. First, osteoblast-like cells as well as a marked reaction for osteonectin, osteopontin and its ligand CD44 were observed as early as 2 days after implantation at the interface around HA/Coll implants. Further, reactivity for ED1 and cathepsin D, both markers for phagocytotic cells, appeared earlier and stronger around HA/Coll. In cell counts, a significantly higher average number of ED1- and cathepsin D-positive phagocytotic cells was observed around the HA/Coll implants on days 6 (p < 0.01), 14 and 28 (p < 0.05). The number of osteopontin-positive cells was significantly higher around HA/Coll implants at days 6 and 14 (p < 0.05). Two weeks after the implantation, first islands of newly formed woven bone were observed around the HA/Coll implant, but not around the control implant. The amount of direct bone contact after 28 days averaged 28% around pure HA and 51% around HA/Coll implants (p < 0.05). While both implants displayed a good osteoconductivity, a higher bone remodelling activity was observed around collagen-containing HA implants compared to pure HA implants. It appears that the addition of collagen to HA implants can enhance both phagocytotic and osteogenic processes. This may result in an earlier acceptance and better osseointegration of the HA/Coll implants into the surrounding tissue.
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Affiliation(s)
- Stefan Rammelt
- Department of Trauma and Reconstructive Surgery, University Hospital Carl Gustav Carus, Technical University Dresden, DE-01307 Dresden, Germany.
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Meyer DC, Gorbunov A, Pompe W, Levin AA. Formation of diffusion-hindering interlayers in metals in contact by dedicated thermal treatment. Cryst Res Technol 2005. [DOI: 10.1002/crat.200410315] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Gorbunov A, Levin AA, Meyer DC, Bischoff L, Eckert D, Köhler B, Mertig M, Weißbach T, Wieser E, Pompe W. Correlation of structural and physical properties of metastable Fe-Cr phases. Cryst Res Technol 2004. [DOI: 10.1002/crat.200410313] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Vyalikh DV, Danzenbächer S, Mertig M, Kirchner A, Pompe W, Dedkov YS, Molodtsov SL. Electronic structure of regular bacterial surface layers. Phys Rev Lett 2004; 93:238103. [PMID: 15601208 DOI: 10.1103/physrevlett.93.238103] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/16/2004] [Indexed: 05/24/2023]
Abstract
We report photoemission and near-edge x-ray absorption fine structure measurements of the occupied and unoccupied valence electronic states of the regular surface layer of Bacillus sphaericus, which is widely used as the protein template for the fabrication of metallic nanostructures. The two-dimensional protein crystal shows a semiconductorlike behavior with a gap value of approximately 3.0 eV and the Fermi energy close to the bottom of the lowest unoccupied molecular orbital. We anticipate that these results will open up new possibilities for the electric addressability of biotemplated low-dimensional hybrid structures.
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Affiliation(s)
- Denis V Vyalikh
- Institut für Festkörperphysik, Technische Universität Dresden, D-01062 Dresden, Germany
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Simon P, Lichte H, Wahl R, Mertig M, Pompe W. Electron holography of non-stained bacterial surface layer proteins. Biochim Biophys Acta 2004; 1663:178-87. [PMID: 15157620 DOI: 10.1016/j.bbamem.2004.03.005] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/08/2003] [Revised: 03/09/2004] [Accepted: 03/16/2004] [Indexed: 11/30/2022]
Abstract
We report transmission electron microscopy (TEM) investigations on bacterial surface layers (S-layers) which belong to the simplest biomembranes existing in nature. S-layers are regular 2D protein crystals composed of single protein or glycoprotein species. In their native form, S-layers are weak phase objects giving only poor contrast in conventional TEM. Therefore, they are usually examined negatively stained. However, staining with heavy metal compounds may cause the formation of structural artefacts. In this work, electron microscopy studies of non-stained S-layers of Bacillus sphaericus NCTC 9602 were performed. Compared to other proteins, these S-layers are found relatively stable against radiation damage. Electron holography was applied where information about phase and amplitude of the diffracted electron wave is simultaneously obtained. In spite of small phase shifts observed, the phase image reconstructed from the hologram of the non-stained S-layer is found to be sensitive to rather slight structure and thickness variations. The lateral resolution, obtained so far, is less than that of conventional electron microscopy of negatively stained S-layers. It corresponds to the main lattice planes of 12.4 nm observed in the reconstructed electron phase image. In addition, as a unique feature of electron holography the phase image provides thickness information. Thus, the existence of double layers of the protein crystals could be easily visualized by the height profile of the specimen.
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Affiliation(s)
- P Simon
- Triebenberg Laboratory, Institute of Structure Physics, Dresden University, D-01062 Dresden, Germany.
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Seidel R, Colombi Ciacchi L, Weigel M, Pompe W, Mertig M. Synthesis of Platinum Cluster Chains on DNA Templates: Conditions for a Template-Controlled Cluster Growth. J Phys Chem B 2004. [DOI: 10.1021/jp037800r] [Citation(s) in RCA: 153] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Schliephake H, Tavassol F, Gelinsky M, Dard M, Sewing A, Pompe W. Use of a mineralized collagen membrane to enhance repair of calvarial defects in rats. Clin Oral Implants Res 2004; 15:112-8. [PMID: 14731184 DOI: 10.1111/j.1600-0501.2004.00992.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
The aim of the present study was to evaluate mineralized collagen membranes for enhancement of bone regeneration in calvarial defects. Forty adult female Sprague-Dawley rats received calvarial full thickness defects with a diameter of 8 mm. In 20 animals, the defects were covered with a mineralized collagen membrane, and 20 animals served as controls. After 6, 13, 26 and 52 weeks, bone regeneration was evaluated using undecalcified thick-section histometry. There was no clear enhancement of bone regeneration during the first 26 weeks after the operation. Bone regeneration underneath the membrane produced consistently thicker bone, albeit without statistical significance. Accumulation of membrane material occurred in the center of the defects surrounded by multinuclear giant cells during early stages of healing. After complete resorption of the membrane, significantly increased bone formation was seen after 52 weeks in the defects that had received membrane coverage. It was concluded that mineralization in the present form did not increase mechanical strength of the membrane to prevent interference of the membrane with bone regeneration in the defect. The reason for the increase in bone formation after resorption of the membrane after 26 weeks remains to be clarified.
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Affiliation(s)
- Henning Schliephake
- Department of Oral and Maxillofacial Surgery, George-Augusta-University, Goettingen, Germany.
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Reinstorf A, Ruhnow M, Gelinsky M, Pompe W, Hempel U, Wenzel KW, Simon P. Phosphoserine--a convenient compound for modification of calcium phosphate bone cement collagen composites. J Mater Sci Mater Med 2004; 15:451-455. [PMID: 15332616 DOI: 10.1023/b:jmsm.0000021119.14870.3d] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Temporary bone replacement materials on the basis of calcium phosphates and hydroxyapatite (HAP) are used in surgery for filling bone defects. Components which are able to control the nucleation and crystal growth of HAP through their functional groups and which can additionally activate bone cells may be helpful in the development of materials with enhanced remodelling in vivo. In this study, the influence of O-phospho-L-serine (PS) on the materials properties of calcium phosphate bone cement composites was investigated. For up to an addition of 25 mg/g PS a strong increase in the stability of the cements under load was determined. The material was studied by scanning electron microscopy and transmission electron microscopy. A more dense microstructure and a plate-like morphology of the HAP-crystals were detected in the modified composites compared with the non-modified samples. By X-ray powder diffraction an inhibition of the dissolution of alpha-tricalcium phosphate (alpha-TCP) and dicalciumphosphate anhydrous (DCPA) particles was found. alpha-TCP and DCPA are the main constituents of the cement precursor. The results of cell culture studies using rat calvaria osteoblasts demonstrate a good viability of the cells on the PS-modified material. Furthermore, the proliferation and differentiation were found to be enhanced on the PS-modified material.
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Affiliation(s)
- A Reinstorf
- Dresden University of Technology, Department of Materials Science, Max Bergmann Center of Biomaterials, Budapester Str 27, 01062 Dresden, Germany.
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Abstract
Two different single-walled carbon nanotube (SWNT) growth modes (cap growth mode and circumference growth mode) are shown to exist. General SWNT diameter windows are derivable from catalyst particle size considerations. In addition, an almost complete picture of nanotube diameter dependencies for the cap growth mode is drawn from experiment. The nanotube diameter always scales linear with temperature, but the degree of dependence varies with the catalyst element. The nanotube diameter scales logarithmically with the gas pressure and catalyst composition. Very few or exactly one atom of a catalyst additive is sufficient to induce SWNT diameter changes. The experimental data allow the conclusion that the observed nanotube diameter is based on materials properties of sp2-bonded carbon/graphene sheets, on individual properties of the catalyst elements, and on additional kinetic components from temperature and pressure changes. Indications are found for a specific and maybe decisive role of adsorbate atoms at the surface of a catalyst particle on the nanotube diameter and therefore on the process of nanotube nucleation and growth.
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Affiliation(s)
- Oliver Jost
- Dresden University of Technology, Dresden, Germany
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Böttcher H, Soltmann U, Mertig M, Pompe W. Biocers: ceramics with incorporated microorganisms for biocatalytic, biosorptive and functional materials development. ACTA ACUST UNITED AC 2004. [DOI: 10.1039/b401724b] [Citation(s) in RCA: 92] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Hempel U, Reinstorf A, Poppe M, Fischer U, Gelinsky M, Pompe W, Wenzel KW. Proliferation and differentiation of osteoblasts on Biocement D modified with collagen type I and citric acid. ACTA ACUST UNITED AC 2004; 71:130-43. [PMID: 15368237 DOI: 10.1002/jbm.b.30082] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
In this study, the proliferation and differentiation of rat calvarial osteoblasts cultured on either (1) calcium-phosphate bone cement Biocement D, (2) Biocement D with 2.5% (w/w) mineralized collagen type I, or (3) Biocement D with 2.5% (w/w) mineralized collagen type I and 3% (w/w) citric acid were investigated. Incubation of the composites in cell-culture medium resulted in a fast decrease of pH and calcium concentration as well as in an increase of phosphate concentration. Although these effects occurred with all investigated materials, the lowest extent could be observed for the citric-acid-containing composites. As shown by scanning-electron microscopy, osteoblasts adhered to the composite surfaces. Proliferation and differentiation of the cells grown on the composites were found to be reduced compared to cells grown on tissue-culture polystyrene. Cells cultured in the vicinity of the composites but without direct contact also exhibited a reduced rate of proliferation, reduced alkaline phosphatase activity, and reduced mineralization. Simulating the changes in calcium and phosphate concentration occasioned by the composites through exposing cells to EGTA and phosphate gives rise to the same effects of reducing proliferation, ALP activity, and mineralization. No indication for apoptosis in cells exposed to low calcium and high phosphate concentrations was found. The number of necrotic cells, however, increased after incubation with EGTA and phosphate. For assessment of cell-composite interactions and the success of the composites in vivo, as well as for more effective material development, it seems to be important to know how changes in microenvironmental pH and ion composition of the material affect cellular proliferation and differentiation.
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Affiliation(s)
- U Hempel
- Institute of Physiological Chemistry, Medical Faculty Carl Gustav Carus, Dresden University of Technology, Fiedlerstrasse 42, D-01307 Dresden, Germany.
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Colombi Ciacchi L, Pompe W, De Vita A. Growth of Platinum Clusters via Addition of Pt(II) Complexes: A First Principles Investigation. J Phys Chem B 2003. [DOI: 10.1021/jp026698f] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Lucio Colombi Ciacchi
- Institut für Werkstoffwissenschaft, Technische Universität Dresden, D-01069 Dresden, Germany
| | - Wolfgang Pompe
- Institut für Werkstoffwissenschaft, Technische Universität Dresden, D-01069 Dresden, Germany
| | - Alessandro De Vita
- Dipartimento di Ingegneria dei Materiali e Chimica Applicata, Università di Trieste, I-34100 Trieste, Italy, and INFM-DEMOCRITOS National Simulation Center, Trieste, Italy
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Borowiak-Palen E, Pichler T, Liu X, Knupfer M, Graff A, Jost O, Pompe W, Kalenczuk R, Fink J. Reduced diameter distribution of single-wall carbon nanotubes by selective oxidation. Chem Phys Lett 2002. [DOI: 10.1016/s0009-2614(02)01253-8] [Citation(s) in RCA: 78] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Paufler P, Levin AA, Meyer DC, Gorbunov A, Tselev A, Pompe W. Metastable phase formation and subsequent thermally stimulated relaxation of co-deposited Fe-Cr nanometer films. Acta Crystallogr A 2002. [DOI: 10.1107/s0108767302098914] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
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Knepper-Nicolai B, Reinstorf A, Hofinger I, Flade K, Wenz R, Pompe W. Influence of osteocalcin and collagen I on the mechanical and biological properties of Biocement D. Biomol Eng 2002; 19:227-31. [PMID: 12202187 DOI: 10.1016/s1389-0344(02)00036-9] [Citation(s) in RCA: 59] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
In order to generate a calcium-phosphate bone cement as a transient replacement for bone defects, we modified Biocement D (Merck Biomaterial GmbH) containing mineralised collagen with osteocalcin, the most abundant non-collageneous protein of bone. Osteocalcin was added to the cement paste during setting in order to control the crystallisation kinetics of hydroxyapatite (HAP) as well as to stimulate the interaction of osteoblasts and osteoclasts with the bone replacement material. Analysis by SEM and AFM shows, that the addition of osteocalcin causes a nanosize microstructure of the calcium cement, which can be explained by inhibited growth of HAP crystals. The fracture strength of the material decreased by incorporation of osteocalcin, pointing onto a higher defect concentration of the crystalline structure. The impact of osteocalcin onto the interaction of bone cells with HAP-Collagen I-cements was studied in a cell culture system using the human osteosarcoma cell line SAOS-2. Results suggest, that osteocalcin might possibly improve the initial adherence of osteoblast-like cells, whereas proliferation of the cells is not effected.
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Affiliation(s)
- B Knepper-Nicolai
- Institut für Werkstoffwissenschaft, Technische Universität Dresden, Hallwachsstr. 3, 01069 Dresden, Germany
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Jost O, Gorbunov AA, Möller J, Pompe W, Liu X, Georgi P, Dunsch L, Golden MS, Fink J. Rate-Limiting Processes in the Formation of Single-Wall Carbon Nanotubes: Pointing the Way to the Nanotube Formation Mechanism. J Phys Chem B 2002. [DOI: 10.1021/jp013138s] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- O. Jost
- Institute of Materials Science, Dresden University of Technology, D-01062 Dresden, Germany, and Institute for Solid State Research, IFW Dresden, P.O. Box 270016, D-01171 Dresden, Germany
| | - A. A. Gorbunov
- Institute of Materials Science, Dresden University of Technology, D-01062 Dresden, Germany, and Institute for Solid State Research, IFW Dresden, P.O. Box 270016, D-01171 Dresden, Germany
| | - J. Möller
- Institute of Materials Science, Dresden University of Technology, D-01062 Dresden, Germany, and Institute for Solid State Research, IFW Dresden, P.O. Box 270016, D-01171 Dresden, Germany
| | - W. Pompe
- Institute of Materials Science, Dresden University of Technology, D-01062 Dresden, Germany, and Institute for Solid State Research, IFW Dresden, P.O. Box 270016, D-01171 Dresden, Germany
| | - X. Liu
- Institute of Materials Science, Dresden University of Technology, D-01062 Dresden, Germany, and Institute for Solid State Research, IFW Dresden, P.O. Box 270016, D-01171 Dresden, Germany
| | - P. Georgi
- Institute of Materials Science, Dresden University of Technology, D-01062 Dresden, Germany, and Institute for Solid State Research, IFW Dresden, P.O. Box 270016, D-01171 Dresden, Germany
| | - L. Dunsch
- Institute of Materials Science, Dresden University of Technology, D-01062 Dresden, Germany, and Institute for Solid State Research, IFW Dresden, P.O. Box 270016, D-01171 Dresden, Germany
| | - M. S. Golden
- Institute of Materials Science, Dresden University of Technology, D-01062 Dresden, Germany, and Institute for Solid State Research, IFW Dresden, P.O. Box 270016, D-01171 Dresden, Germany
| | - J. Fink
- Institute of Materials Science, Dresden University of Technology, D-01062 Dresden, Germany, and Institute for Solid State Research, IFW Dresden, P.O. Box 270016, D-01171 Dresden, Germany
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Mertig M, Klemm D, Zänker H, Pompe W. Scanning force microscopy of two-dimensional structure formation in thin humic acid films. SURF INTERFACE ANAL 2002. [DOI: 10.1002/sia.1173] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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