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  • 1
    Electronic Resource
    Electronic Resource
    Weinheim [u.a.] : Wiley-Blackwell
    Materials and Corrosion/Werkstoffe und Korrosion 45 (1994), S. 170-171 
    ISSN: 0947-5117
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Microbial deterioration of materials - case histories and countermeasures for plastics and natural materials: Biodeterioration of silicone elastomers
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Cell spreading and cell division rates of a transformed line of mouse lung fibroblasts were studied on various polymer surfaces in the presence of serum proteins. The bare polymer surfaces, as well as the protein-coated surfaces, were characterized by their polar (γsp) and dispersion (γsd) surface free energies. Cell spreading appeared to be dependent on the polar surface free energy. Cell spreading is low when the γsp of the bare surface is lower than 5 erg cm-2; marked spreading occurs when γsp is higher than 15 erg cm-2. A similar relationship was found between cell spreading and polarity of the protein-coated surfaces, although less pronounced than for the bare surfaces. Cell spreading appeared independent of the dispersion surface free energy. Cell division rate was the same on all surfaces tested.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 20 (1986), S. 773-784 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: To determine whether the surface free energy of polymer materials influences the spreading and growth of cells, surface free energies of 13 polymers and glass were related to spreading and growth of human skin fibroblasts. Experiments were performed in both the presence and absence of serum proteins. We calculated the surface free energy from contact angles of phosphate-buffered saline (PBS), n-propanol/PBS mixtures, and α-bromonaphthalene on the polymers, using the concept of polar and dispersion components accounting for spreading pressures. Cell spreading and substratum surface free energy (γs) showed a characteristic sigmoid relationship both in the presence and in the absence of serum proteins; good spreading only occurred when γs was higher than approximately 57 erg · cm-2. In the presence of serum proteins, cell spreading is similar on most materials; only few materials show relatively high cell spreading. Cell growth in the presence of serum proteins did not differ significantly on the various polymers with reference to their γs values. In contrast, two groups of polymers could be distinguished in the absence of serum with respect to cell growth. The first group showed increasing γs, whereas the second group showed consistently low cell growth. The results demonstrate the complex relationship between cell spreading and substratum surface free energy as well as the role of serum proteins in modifying the surface characteristics of polymers in relation to cell spreading and growth.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: In this article we studied the adsorption of serum albumin to substrata with a broad range of wettabilities from solutions with protein concentrations between 0.03 and 3.00 mg · mL-1 in a parallel-plate flow cell. Wall shear rates were varied between 20 and 2000 s-1. The amount of albumin adsorbed in a stationary state was always highest on PTFE, the most hydrophobic material employed and decreased with increasing wettability of the substrata. Increasing stationary amounts of adsorbed albumin were observed with increasing wall shear rates at the lowest protein concentration. Inverse observations were made at the highest protein concentration. Transmission electron micrographs of replicas from the albumin-coated substrata showed that proteins were mostly adsorbed in islandlike structures on the hydrophobic substrata. The tendency to form islandlike structures was shear rate- and concentration-dependent and disappeared gradually going to more hydrophilic substrata. On glass, the most hydrophilic material employed, a homogeneous, well distributed, fine knotted, reticulated structure was found. In conclusion, this study demonstrates that both the amount of adsorbed albumin as well as the surface structure of the adsorbed proteins are regulated by the substratum wettability. This observation may well account for the fact that substratum properties can be transferred by an adsorbed protein film to the interface with adhering cells or microorganisms.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 26 (1992), S. 725-738 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: A parallel-plate flow chamber is developed in order to study cellular adhesion phenomena. An image analysis system is used to observe individual cells exposed to flow in situ and to determine area, perimeter, and shape of these cells as a function of time and shear stress. With this flow system the behavior of human fibroblasts spread on glass is studied when exposed to an increasing laminar flow. The flow system appears to be well-suited for following individual cells during detachment. After 75 to 90 min, at a shear stress of 350 dynes/cm2, more than 50% of the spread cells are detached from the surface. Cells with higher spreading areas stay longer at the glass surface. Cells round up before detaching. Sometimes the cell body is attached to the substratum through a thin filament during detachment. At the scanning electron microscopy level numerous filopodial extensions are observed. Cell material could only rarely be observed at the light or scanning electron microscopic level on the substratum once a cell was detached.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 34 (1997), S. 201-209 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Adhesion of yeasts and bacteria to silicone rubber is one of the first steps in the biodeterioration of silicone rubber voice prostheses. In this paper, adhesion of two streptococcal, staphylococcal, Candida albicans and Candida tropicalis strains, isolated from explanted voice prostheses was investigated to silicone rubber with and without a salivary conditioning film in a parallel-plate flow chamber. Within each microbial pair of one species, the strain with the most negative zeta potential adhered most slowly to negatively charged silicone rubber. No other clear relationships were obvious between adhesion to silicone rubber and microbial zeta potentials or cell-surface hydrophobicities, as by water contact angles. A 1.5-h adsorbed salivary conditioning film appeared to possess components, presumably albumin and lysozyme, slowing down the deposition of the yeasts and some of the streptococcal and staphylococcal isolates. In addition, microbial adhesion in a stationary end point was generally lower to silicone rubber with an adsorbed salivary conditioning film than without one. Nearly all microorganisms adhering to an adsorbed salivary conditioning film, yeasts as well as bacteria, were stimulated to detach by the passage of an air bubble through the chamber, but microorganisms adhering directly to the silicone rubber, especially C tropicalis strains, detached in far lower numbers under the influence of a passing air bubble. The present observations are in agreement with clinical in vivo findings that in patients with reduced saliva production after radiotherapy, the device life of the voice prosthesis is significantly shortened and suggests that isolated salivary components might be used as an anti-adhesive. © 1997 John Wiley & Sons, Inc.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 17 (1983), S. 637-641 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: In this study, the dispersion (γsd) and polar (γsp) surface free energies of human enamel with and without an acquired enamel pellicle and of crystalline hydroxyapatite were determined from contact angle measurements. The results show that γsp is strongly influenced by the presence of a pellicle; the total surface free energy (γs) is considerably smaller for enamel with an acquired pellicle than for enamel without an acquired pellicle. Enamel without an acquired enamel pellicle shows surface free energies comparable with those of crystalline hydroxyapatite.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 29 (1995), S. 1415-1423 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: In this study, adhesion and spreading of human skin fibroblasts on gradient surfaces of dichlorodimethylsilane (DDS) coupled to glass was investigated. Gradient surfaces were prepared by the diffusion technique and characterized by the Wilhelmy plate technique for their wettability and by scanning x-ray photoelectron spectroscopy for their chemical surface composition. A linear relation between the gradient length, based on advancing water contact angles, and the square root of the diffusion time of DDS was observed. XPS analysis and the cellular experiments were carried out on gradient surfaces prepared using diffusion time of 3 h. A continuously varying chemical composition over the length of the gradient surfaces observed with the Si/O elemental surface concentration ratio being highest on the hydrophobic end of the gradient surfaces. In the presence of serum proteins, human skin fibroblasts seeded on these gradient surfaces showed a preferential adhesion onto the steepest part of the gradient, probably due to an optimal local wettability and/or local chemistry. Furthermore, it was shown that the spread area of human fibroblasts increased over the length of the gradient surface when going from the hydrophobic to the hydrophilic end. Summarizing, this study shows that the use of gradient surfaces to study cellular responses to materials surface properties, like wettability, yields more-convincing conclusions than the use of a variety of materials with different wettabilities due to the control of the specific surface chemistry of gradient surfaces. © 1995 John Wiley & Sons, Inc.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 22 (1988), S. 1023-1032 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: In order to develop a muco-adhesive hydrogel for buccal drug delivery it is necessary to understand fully the properties determining adhesiveness as well as mechanisms involved. In this study we measured glass transition temperatures, water contact angles and the peel- and shear detachment forces from porcine oral mucosa, of acrylic acid and butyl acrylate copolymers. The contact angle maximizes at 50% butyl acrylate content. The glass transition temperature decreases from 0% to 100% butyl acrylate. There seems to exist a certain combination of contact angle and glass transition temperature which is related to adhesiveness. This strongly suggests that, in order to obtain a muco-adhesive hydrogel, at least two properties have to be optimized: (1) the polarity of the polymer surface and (2) the molecular mobility of the polymer groups.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    Surface and Interface Analysis 15 (1990), S. 344-346 
    ISSN: 0142-2421
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: In this paper, the stationary charging voltage of human dental enamel samples due to photoelectron ejection in an x-ray photoelectron spectrometer is related to the amount of material adsorbed from commercially available mouthrinses and the adsorbed layer thickness. A clear relationship was observed between the charging voltage versus the C/Ca elemental surface concentration ratio, taken as a measure of the amount of adsorbed material. Consequently, a similar relationship was found between charging versus adsorbed layer thickness.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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