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  • Polymer and Materials Science  (4,076)
  • 1995-1999  (1,164)
  • 1990-1994  (1,705)
  • 1980-1984  (1,207)
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  • 1
    Electronic Resource
    Electronic Resource
    Effect of titanium surface roughness on proliferation, differentiation, and protein synthesis of human osteoblast-like cells (MG63) (1995)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 29 (1995), S. 389-401 
    Details
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: The effect of surface roughness on osteoblast proliferation, differentiation, and protein synthesis was examined. Human osteoblast-like cells (MG63) were cultured on titanium (Ti) disks that had been prepared by one of five different treatment regimens. All disks were pretreated with hydrofluoric acid-nitric acid and washed (PT). PT disks were also: washed, and then electropolished (EP); fine sandblasted, etched with HCl and H2SO4, and washed (FA); coarse sandblasted, etched with HCl and H2SO4, and washed (CA); or Ti plasma-sprayed (TPS). Standard tissue culture plastic was used as a control. Surface topography and profile were evaluated by brightfield and darkfield microscopy, cold field emission scanning electron microscopy, and laser confocal microscopy, while chemical composition was mapped using energy dispersion X-ray analysis and elemental distribution determined using Auger electron spectroscopy. The effect of surface roughness on the cells was evaluated by measuring cell number, [3H]thymidine incorporation into DNA, alkaline phosphatase specific activity, [3H]uridine incorporation into RNA, [3H]proline incorporation into collagenase digestible protein (CDP) and noncollagenase-digestible protein (NCP), and [35S]sulfate incorporation into proteoglycan.Based on surface analysis, the five different Ti surfaces were ranked in order of smoothest to roughest: EP, PT, FA, CA, and TPS. A TiO2 layer was found on all surfaces that ranged in thickness from 100 Å in the smoothest group to 300 Å in the roughest. When compared to confluent cultures of cells on plastic, the number of cells was reduced on the TPS surfaces and increased on the EP surfaces, while the number of cells on the other surfaces was equivalent to plastic. [3H]Thymidine incorporation was inversely related to surface roughness. Alkaline phosphatase specific activity in isolated cells was found to decrease with increasing surface roughness, except for those cells cultured on CA. In contrast, enzyme activity in the cell layer was only decreased in cultures grown on FA- and TPS-treated surfaces. A direct correlation between surface roughness and RNA and CDP production was found. Surface roughness had no apparent effect on NCP production. Proteoglycan synthesis by the cells was inhibited on all the surfaces studied, with the largest inhibition observed in the CA and EP groups. These results demonstrate that surface roughness alters osteoblast proliferation, differentiation, and matrix production in vitro. The results also suggest that implant surface roughness may play a role in determining phenotypic expression of cells in vivo.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jbm.820290314
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  • 2
    Electronic Resource
    Electronic Resource
    Effect of titanium surface roughness on chondrocyte proliferation, matrix production, and differentiation depends on the state of cell maturation (1996)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 30 (1996), S. 145-155 
    Details
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Although it is well accepted that implant success is dependent on various surface properties, little is known about the effect of surface roughness on cell metabolism or differentiation, or whether the effects vary with the maturational state of the cells interacting with the implant. In the current study, we examined the effect of titanium (Ti) surface roughness on chondrocyte proliferation, differentiation, and matrix synthesis using cells derived from known stages of endochondral development. Chondrocytes derived from the resting zone (RCs) and growth zone (GCs) of rat costochondral cartilage were cultured on Ti disks that were prepared as follows: HF-HNO3-treated and washed (PT); PT-treated and electropolished (EP); fine sand-blasted, HCl-H2SO4-etched, and washed (FA); coarse sand-blasted, HCl-H2SO4-etched, and washed (CA); or Ti plasma-sprayed (TPS). Based on surface analysis, the Ti surfaces were ranked from smoothest to roughest: EP, PT, FA, CA, and TPS. Cell proliferation was assessed by cell number and [3H]-thymidine incorporation, and RNA synthesis was assessed by [3H]-uridine incorporation. Differentiation was determined by alkaline phosphatase specific activity (AL-Pase). Matrix production was measured by [3H]-proline incorporation into collagenase-digestible (CDP) and noncollagenase-digestible (NCP) protein and by [35S]-sulfate incorporation into proteoglycan. GCs required two trypsinizations for complete removal from the culture disks; the number of cells released by the first trypsinization was generally decreased with increasing surface roughness while that released by the second trypsinization was increased. In RC cultures, cell number was similarly decreased on the rougher surfaces; only minimal numbers of RCs were released by a second trypsinization. [3H]-thymidine incorporation by RCs decreased with increasing surface roughness while that by GCs was increased. [3H]-Uridine incorporation by both GCs and RCs was greater on rough surfaces. Conversely, ALPase in the cell layer and isolated cells of both cell types was significantly decreased. GC CDP and NCP production was significantly decreased on rough surfaces while CDP production by RC cells was significantly decreased on smooth surfaces. [35S]-sulfate incorporation by RCs and GCs was decreased on all surfaces compared to tissue culture plastic. The results of this study indicate that surface roughness affects chondrocyte proliferation, differentiation, and matrix synthesis, and that this regulation is cell maturation dependent. © 1996 John Wiley & Sons, Inc.
    Additional Material: 9 Ill.
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  • 3
    Electronic Resource
    Electronic Resource
    Titanium surface roughness alters responsiveness of MG63 osteoblast-like cells to 1α,25-(OH)2D3 (1998)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 39 (1998), S. 77-85 
    Details
    ISSN: 0021-9304
    Keywords: implant ; titanium ; osteoblasts ; surface roughness ; 1α,25- (OH)2D3 ; differentiation ; local factor ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Surface roughness has been shown to affect differentiation and local factor production of MG63 osteoblast-like cells. This study examined whether surface roughness alters cellular response to circulating hormones such as 1α,25-(OH)2D3. Unalloyed titanium (Ti) disks were pretreated with HF/HNO3 (PT) and then were machined and acid-etched (MA). Ti disks also were sandblasted (SB), sandblasted and acid etched (CA), or plasma sprayed with Ti particles (PS). The surfaces, from smoothest to roughest, were: PT, MA, CA, SB, and PS. MG63 cells were cultured to confluence on standard tissue culture polystyrene (plastic) or the Ti surfaces and then treated for 24 h with either 10-8M or 10-7M 1α,25-(OH)2D3 or vehicle (control). Cellular response was measured by assaying cell number, cell layer alkaline phosphatase specific-activity, and the production of osteocalcin, latent (L) TGFβ, and PGE2. Alkaline phosphatase activity was affected by surface roughness; as the surface became rougher, the cells showed a significant increase in alkaline phosphatase activity. Addition of 1α,25-(OH)2D3 to the cultures caused a dose-dependent stimulation of alkaline phosphatase activity that was synergistic with the effect caused by surface roughness alone. 1α,25-(OH)2D3 also caused a synergistic increase in osteocalcin production as well as local factor (LTGFβ and PGE2) production on the rougher CA, SB, and PS surfaces, but it had no effect on the production on smooth surfaces. The inhibitory effect of surface roughness on cell number was not affected by 1α,25-(OH)2D3 except on the SB surface. 1α,25-(OH)2D3 decreased cell number, increased alkaline phosphatase activity and osteocalcin production, and had no effect on LTGFβ or PGE2 production by MG63 cells grown on tissue culture polystyrene. These data suggest that bone cell response to systemic hormones is modified by surface roughness and that surface roughness increases the responsiveness of MG63 cells to 1α,25-(OH)2D3. They also suggest that the endocrine system is actively involved in normal bone healing around implants. © 1998 John Wiley & Sons, Inc. J Biomed Mater Res, 39, 77-85, 1998.
    Additional Material: 6 Ill.
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  • 4
    Electronic Resource
    Electronic Resource
    Surface roughness modulates the local production of growth factors and cytokines by osteoblast-like MG-63 cells (1996)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 32 (1996), S. 55-63 
    Details
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Titanium (Ti) surface roughness affects proliferation, differentiation, and matrix production of MG-63 osteoblast-like cells. Cytokines and growth factors produced in the milieu surrounding an implant may also be influenced by its surface, thereby modulating the healing process. This study examined the effect of surface roughness on the production of two factors known to have potent effects on bone, prostaglandin E2 (PGE2) and transforming growth factor β1 (TGF-β1). MG-63 cells were cultured on Ti disks of varying roughness. The surfaces were ranked from smoothest to roughest: electropolished (EP), pretreated with hydrofluoric acid-nitric acid (PT), fine sand-blasted, etched with HCl and H2SO4, and washed (EA), coarse sand-blasted, etched with HCl and H2SO4, and washed (CA), and Ti plasma-sprayed (TPS). Cells were cultured in 24-well polystyrene (plastic) dishes as controls and to determine when confluence was achieved. Media were collected and cell number determined 24 h postconfluence. PGE2 and TGF-β1 levels in the conditioned media were determined using commercial radioimmunoassay and enzyme-linked immunosorbent assay kits, respectively. There was an inverse relationship between cell number and Ti surface roughness. Total PGE2 content in the media of cultures grown on the three roughest surfaces (FA, CA, and TPS) was significantly increased 1.5-4.0 times over that found in media of cultures grown on plastic or smooth surfaces. When PGE2 production was expressed per cell number, CA and TPS cultures exhibited six- to eightfold increases compared to cultures on plastic and smooth surfaces. There was a direct relationship between TGF-β1 production and surface roughness, both in terms of total TGF-β1 per culture and when normalized for cell number. TGF-β1 production on rough surfaces (CA and TPS) was three to five times higher than on plastic. These studies indicate that substrate surface roughness affects cytokine and growth factor production by MG-63 cells, suggesting that surface roughness may modulate the activity of cells interacting with an implant, and thereby affect tissue healing and implant success. © 1996 John Wiley & Sons, Inc.
    Additional Material: 5 Ill.
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  • 5
    Electronic Resource
    Electronic Resource
    Poly(dimethylsiloxane)-poly(ethylene oxide)-heparin block copolymers III: Surface and bulk compositional differences (1990)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 24 (1990), S. 547-571 
    Details
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Previously observed bioactivity of poly(dimethylsiloxane)-poly(ethyelene oxide)-heparin (PDMS-PEO-Hep) triblock copolymers has prompted studies of the surface and bulk character of this copolymer using angular-dependent electron spectroscopy for chemical analysis (ADESCA), static secondary mass spectroscopy (SIMS), differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA). Because the low-energy PDMS phase dominates surfaces of this copolymer when solvent cast under air or vacuum conditions, attempts were made to explain surface restructuring and rearrangements induced in hydrated or aqueous environments that permit surface accessibility and bioactivity of heparin moieties. Based on comparisons with PDMS, PEO, and heparin homopolymers, PEO/heparin blends, and an unheparinized PDMS-PEO diblock copolymer, PDMS-PEO-heparin demonstrates both phase-mixed and phase-separated regions in DSC analysis. During annealing cycles above the Tg values of the copolymer constituents, phase-mixed regions become increasingly phase separated and PEO enriched. TGA analysis confirmed the presence of block copolymer constituents and presented evidence of intermolecular segmental interactions, hence phase-mixing in the copolymers. ADESCA analysis indicates that the outer 5 Å of both the PDMS-PEO and PDMS-PEO-Hep copolymers is essentially pure PDMS. However, significant amounts of PEO are detected 5 to 20 Å below the surface. Static SIMS also detects the presence of PDMS at the surfaces of the PDMS-PEO and PDMS-PEO-Hep copolymers. Compositional models based on ADESCA, SIMS, and DSC data are presented for desiccated and hydrated copolymer surfaces.
    Additional Material: 16 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jbm.820240503
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  • 6
    Electronic Resource
    Electronic Resource
    Prostaglandins mediate the effects of titanium surface roughness on MG63 osteoblast-like cells and alter cell responsiveness to 1α,25-(OH)2D3 (1998)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 41 (1998), S. 489-496 
    Details
    ISSN: 0021-9304
    Keywords: implant ; titanium ; osteoblasts ; prostaglandin ; indomethacin ; surface roughness ; 1α,25-(OH)2D3 ; differentiation ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Surface roughness affects proliferation, differentiation (alkaline phosphatase and osteocalcin), local factor production [transforming growth factor (TGFβ) and prostaglandin E2 (PGE2)], and response to 1,25-(OH)2D3 (1,25) of MG63 osteoblast-like cells. In this study, we examined whether the effect of surface roughness on MG63 cells is mediated by prostaglandins produced by the cells. Unalloyed titanium (Ti) disks were pretreated with HF/HNO3 (PT) and then machined and acid-etched (MA). Disks were also coarse grit-sandblasted (SB), coarse grit-sandblasted and acid-etched (CA), or plasma-sprayed with Ti particles (PS). The surfaces, from smoothest to roughest, were PT, MA, CA, SB, and PS. MG63 cells were cultured to confluence on the Ti disks in the presence or absence of 10-7M indomethacin (Indo), a specific inhibitor of cyclooxygenase activity, resulting in decreased prostaglandin production. When the cells reached confluence, cell number, cell layer alkaline phosphatase specific activity (ALPase), and osteocalcin (OC) and latent TGFβ (LTGFβ) production were determined. In addition, confluent cultures which had been grown in the absence of Indo were exposed to 10-7M 1,25, 10-7M Indo, or a combination of the two for 24 h. On the rougher surfaces, cell number was decreased and ALPase, OC, and LTGFβ were increased. When indomethacin was present throughout the culture period, the effect of surface roughness on cell number, OC, and LTGFβ was abolished. ALPase was reduced, but surface roughness-dependent effects were still observed. Addition of indomethacin to confluent cultures for 24 h had no effect on any of the parameters examined, with one exception: Cells cultured on MA surfaces exhibited a more differentiated phenotype. 1,25 increased all parameters examined on SB, CA, and PS surfaces. When indomethacin was added with 1,25, the 1,25-dependent effects on cell number and OC and LTGFβ production were abolished; however, ALPase was unaffected. This indicates that bone cell response to systemic hormones may be modified by implant surface roughness. This effect may be mediated, at least in part, by prostaglandins produced by the same cells. © 1998 John Wiley & Sons, Inc. J Biomed Mater Res, 41, 489-496, 1998.
    Additional Material: 8 Ill.
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  • 7
    Electronic Resource
    Electronic Resource
    Chain orientation and anisotropies in optical and dielectric properties in thin films of stiff polyimides (1992)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 30 (1992), S. 1321-1327 
    Details
    ISSN: 0887-6266
    Keywords: polyimides. stiff, optical and dielectric properties in their films of ; optical anisotropy and chain orientation stiff polyimide thin films ; dielectric properties of stiff polyimide thin films ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Thin films of poly(p-phenylene biphenyltetracarboximide) (BPDA-PDA), prepared by thermal imidization of the precursor poly(amic acid) on substrates, have been investigated by optical waveguide, ultraviolet-visible (UV-VIS), infrared (IR), and dielectric spectroscopies. The polyimide films exhibit an extraordinarily large anisotropy in the refractive indices with the in-plane index n∥ = 1.806 and the out-of-plane index n⊥ = 1.589 at 1064 nm wavelength. No discernible effect of the film thickness on this optical anisotropy is found between films of ca. 2.1 and ca. 7.8 μm thickness. This large birefringence is attributed to the preferential orientation of the biphenyltetracarboximide moieties with their planes parallel to the film surface, coupled with the strong preference of BPDA-PDA chains to align along the film plane. The frequency dispersion of the in-plane refractive index n∥ is consistent with the results calculated by the Lorentz-Lorenz equation from the UV-visible spectrum exhibiting several absorption bands in the 170-500 nm region. The contribution from the IR absorption in the range 7000-400 cm,-1 computed by the Spitzer-Kleinmann dispersion relations from the measured spectra, adds ca. 0.046 to the in-plane refractive index n∥. Tilt-angle-dependent polarized IR results indicate nearly the same increase for the out-of-plane index n⊥. Application of the Maxwell relation then leads to the out-of-plane dielectric constant ε⊥ ≃ 2.7 at 1.2 × 1013 Hz, as compared with the measured value of ca. 3.0 at 106 Hz. Assuming this small difference to remain the same for the in-plane dielectric constants ε∥, we obtain a very large anisotropy in the dielectric properties of these polyimide films with the estimated in-plane dielectric constant ε∥ ≃ 3.4 at 1.2 × 1013 Hz, and ε∥ ≃ 3.7 at 106 Hz. © 1992 John Wiley & Sons, Inc.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/polb.1992.090301203
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  • 8
    Electronic Resource
    Electronic Resource
    NMR relaxation study of thermal degradation in cured PMR polyimidesWork supported in part by NASA under grant NCC-3-164. (1995)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 33 (1995), S. 1545-1557 
    Details
    ISSN: 0887-6266
    Keywords: NMR relaxation ; PMR polyimides ; thermal degradation ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: We have studied cross-linking and thermal degradation of high-performance first-and second-generation PMR-15 polyimides, both thermoset and thermoplastic versions, by performing nonspectroscopic NMR solid echo T*2 relaxation measurements at temperatures up to 430°C using probes built for this purpose. We employ signal averaging and automated decomposition of the relaxation decays into two Gaussian components, the slower of which gradually appears above 300°C. Tracking the molecular mobility spectrum in terms of the relative intensity of the components and their relaxation times as temperature is cycled, we detect essentially no irreversible effects below the glass transition, measure permanent mobility reductions attributable to completion of cure, and find that exposure to temperatures above 380°C on the order of 1 h is required for substantial thermal degradation to occur. These results are closely supported by thermal and mechanical measurements on parallel specimens. Second-generation PMR resins appear to have higher microscopic rigidity and reduced viscous fraction at high temperatures. ©1995 John Wiley & Sons, Inc.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/polb.1995.090331012
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  • 9
    Electronic Resource
    Electronic Resource
    An investigation of surface segregation in magnetron-sputtered NbSi using UPS and AES (1992)
    Chichester [u.a.] : Wiley-Blackwell
    Surface and Interface Analysis 19 (1992), S. 23-26 
    Details
    ISSN: 0142-2421
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: Films of amorphous NbSi prepared by magnetron sputtering were found to have a higher concentration of silicon at the surface than in the bulk material. In this paper we report on measurements of both ultraviolet photoemission spectroscopy and Auger electron spectroscopy carried out on samples prepared in situ at the UK Synchrotron Radiation Source, Daresbury. Spectr taken immediately after sputter deposition show that the surface is rich in silicon, while following argon ion bombardment the bulk composition is slowly revealed with a much greater concentration of niobium. This is observed by a comparison of the relative heights of peaks in the Auger spectra and by resonance effects and the sharpening of the Fermi edge in the UP spectra. Of particular interest are changes around the metal-insulator transition that occur at approximately 11 at.% niobium.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/sia.740190108
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  • 10
    Electronic Resource
    Electronic Resource
    Identification and quantification of Cu contamination on GaAs surfacesPaper presented at QSA 7, Guildford, September 1992. (1994)
    Chichester [u.a.] : Wiley-Blackwell
    Surface and Interface Analysis 21 (1994), S. 51-55 
    Details
    ISSN: 0142-2421
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: Secondary ion mass spectrometry has been used to identify the presence of Cu contamination on undoped semiinsulating GaAs wafer surfaces following polishing under certain conditions. The presence of a contaminating species on the wafer surface is indicated by the influence of pre-etch treatments on electrical measurements performed on heat-treated wafers, with and without Si implants. The identification of Cu as a contaminant is confirmed by photoluminescence measurements. With the appropriate wafer preparation process, the level of Cu contamination is below the SIMS detection limit of 〈1 × 1016 atoms cm-3.In the SIMS analysis of the surface-contaminated wafers, the Cu depth profile shape was dependent on the primary beam bombardment energy, suggesting a chemical segregation of Cu out of the altered layer, a redistribution that is known to occur in Si.To quantify the surface concentration of Cu, GaAs wafers were deliberately contaminated with Cu, heat treated and analysed with glow discharge mass spectrometry and SIMS to provide a cross-calibration.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/sia.740210108
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