摘要:

Pyrolite®has been used in many implantable medical devices over the last 25 years. This test specimen is typical of Pyrolite®as manufactured for implantable products. Minor statistical variation from the reported values can be expected due to variation in the manufacturing process as a result of different component geometries. The data is critical as new pyrolytic carbons that approximate Pyrolite®are developed. The data were collected using a Perkin–Elmer 5000-LS ESCA spectrometer, with monochromated AlKαexcitation at a resolution of 1.7895 eV.

ISSN:1055-5269    

DOI:10.1116/1.1247805

出版商:American Vacuum Society    

年代:1996

数据来源: AIP

摘要:

Biolite®, a vapor deposited, thin, amorphous carbon film, has been used successfully as a component of implantable medical devices during the last 25 years. Biolite®has not been previously characterized using XPS. We have used XPS to explore the chemical composition of Biolite®samples that are typical of those deposited onto implantable medical devices; we report the findings here. This data is an important part of any effort regarding understanding why Biolite®is a good biocompatible material. The data were collected using a Perkin–Elmer 5000-LS ESCA spectrometer with monochromated AlKαexcitation, at a resolution of 1.7895 eV.

ISSN:1055-5269    

DOI:10.1116/1.1247804

出版商:American Vacuum Society    

年代:1996

数据来源: AIP

摘要:

Hydroxyapatite [Ca10(PO4)6(OH)2] is commonly used as a coating material on orthopedic and dental implants. Hydroxyapatite is the major inorganic component of bone and is biocompatible with tissues when used on implants. Quality control tests are critical for the proper calcium to phosphorous ratio and also for checking for the presence of impurities. Being an important surface analytical tool used in the field of biomaterials, x-ray photoelectron spectroscopy was used to examine as-received hydroxyapatite pressed powders.

ISSN:1055-5269    

DOI:10.1116/1.1247808

出版商:American Vacuum Society    

年代:1996

数据来源: AIP

摘要:

The surface composition of anionic polymerized poly(2-hydroxyethyl methacrylate) (PHEMA) films cast onto glass coverslips was examined with x-ray photoelectron spectroscopy (XPS). The elemental composition determined from a survey scan was 68.3 at. % carbon and 31.7 at. % oxygen. This composition is within experimental error of the composition expected based on the structure of PHEMA (66.7 at. % carbon and 33.3 at. % oxygen). The C 1sspectrum was fit using four components corresponding to C—H/C—C, beta-shifted C—H, C—O, and O=C—O species. The O1sspectrum was fit using three components corresponding to C=O, C—OH, and C—O—C species. The assignment, binding energies, and relative areas are all consistent with the structure of PHEMA and previous XPS studies of methacrylates [D. G. Castner and B. D. Ratner, Surf. Interface Anal.15, 479 (1990) and G. P. Lopez, D. G. Castner, and B. D. Ratner,17,ibid.267 (1991)]. The surface composition of PHEMA after reaction of the hydrdoxyl groups with (CH3Si)2NHSi(CH3)3Cl to produce trimethyl silyated PHEMA (PHEMA-TMS) was also examined with XPS. The elemental composition of PHEMA-TMS determined from a survey scan was 69.2 at. % carbon, 21.9 at. % oxygen, and 8.9 at. % silicon. This composition is within experimental error of the composition expected based on the structure of PHEMA-TMS (69.2 at. % carbon, 23.1 at. % oxygen, and 7.7 at. % silicon). The C 1sspectrum was fit using four components corresponding to C—H/C—C, beta-shifted C—H, C—O, and O=C—O species. The O 1sspectrum was fit using two components corresponding to C=O/C—O—Si and C—O—C species. The assignment, binding energies, and relative areas are all consistent with the structure of PHEMA-TMS and previous XPS studies of methacrylates [D. G. Castner and B. D. Ratner, Surf. Interface Anal.15, 479 (1990) and G. P. Lopez, D. G. Castner, and B. D. Ratner,17,ibid.267 (1991)].

ISSN:1055-5269    

DOI:10.1116/1.1247807

出版商:American Vacuum Society    

年代:1996

数据来源: AIP

摘要:

The surface chemical composition of top fermenting brewing yeastSaccharomyces cerevisiaeMUCL 38475 was determined by XPS. The sample was prepared by washing the harvested cells in distilled water, freezing the suspension in liquid nitrogen, freeze drying, filling a trough with the powder and pressing gently. The yeast surface is mainly composed of carbon, oxygen, and nitrogen. Phosphorus and potassium were found as minor elements. The C 1s, O 1s, and N 1speaks were broken down into components which were assigned to chemical functions on the basis of analysis of sugar derivatives and homopeptides. The XPS analysis of brewing yeasts relates the surface chemical composition to physicochemical properties (electrical properties, hydrophobicity) and cell behavior (flocculation, flotation).

ISSN:1055-5269    

DOI:10.1116/1.1247802

出版商:American Vacuum Society    

年代:1996

数据来源: AIP

摘要:

Maltodextrin was analyzed as a model compound representative of polysaccharides. A relatively smooth surface was obtained by pressing the maltodextrin powder in a small trough. The C 1speak component was split into three components with the same FWHM. The main component was found at 286.3 eV and was attributed to carbon involved in the alcohol functions. The component found at 287.8 eV was attributed to carbon in the acetal function; the alcohol to acetal ratio([C_—OH]/[O—C_—O])was 0.21, i.e., close to the stoichiometric ratio 0.20. A component found at 284.8 eV indicated the presence of hydrocarbon-like surface contamination. The O 1speak showed only one component at 532.7 eV; oxygen involved in hydroxyl could not be distinguished from oxygen involved in a acetal function. The surface analysis of model compounds was performed under conditions of practical significance for the analysis of microbial cells and of materials treated by biological fluids. This approach allowed quantification of chemical functions of biosurfaces and modeling of the composition of the latter in terms of classes of biochemical compounds (polysaccharides, proteins, lipids, …)

ISSN:1055-5269    

DOI:10.1116/1.1247803

出版商:American Vacuum Society    

年代:1996

数据来源: AIP

摘要:

Glycine (GL) overlayers of varying thickness were depositedin situon the clean Pt(111) surface by evaporating commercially available glycine powder. The temperature-stabilized evaporation source, made of Cu, was kept at 420 K during evaporation. The distance between Pt and the evaporation source was about 240 mm. The deposition rate and the total amount of glycine deposited were monitored by a quartz crystal microbalance that could be moved to intersect the GL beam approximately 40 mm downstream compared to the Pt position. The total amount of glycine in the reproduced spectra was 34 (~0.5 ML) and 340 ng/cm2(~ 5 ML), respectively. We discuss the spectra with reference to both the neutral and zwitterionic states. There are two glycine-related C 1speaks at both low and high GL coverages and a shoulder at ~ 285 eV most probably due to partial decomposition of glycine inside the evaporation source, at least for a thicker GL layer. The C 1speak at lower binding energy is usually attributed to the C 1scarbon, while the peak at higher BE is supposed to stem from the carboxyl group. The energy of the peaks shifts with coverage, mainly due to the differences in charge transfer between Pt-GL (low coverage) compared to the GL-GL (high coverage). Slight charging of the sample (3.7 meV/ML) takes place, but results in a virtually uniform shift of all the GL levels involved. In the N 1sspectral region there appear two different N 1scomponents. The intensity of the peak at lower BE levels off with increased coverage from ~25% of the total N 1sintensity at low coverage to ~8% at higher coverages. The energy position of this lower BE peak is characteristic of NH2-like bonding. The position of the second N 1speak suggestsNH3+-like bonds. At high GL coverages the N 1speak at low BE, and a C 1sshoulder at 285 eV, stem mainly from a slight decomposition of GL inside the evaporation source (below 8%). At low glycine coverages (<1 ML) there exist two different GL states on the surface: a majority of the amino acid molecules form zwitterions, while the remaining part is either neutral or decomposes into fragments some of which contain the NH2group.

ISSN:1055-5269    

DOI:10.1116/1.1247824

出版商:American Vacuum Society    

年代:1996

数据来源: AIP

摘要:

Commercially pure (c.p., 99.6%) titanium and theTi6Al4Valloy are widely used in biomedical applications. The surface (oxide) properties of these materials play a key role for their function in biomaterial applications, and it is therefore important to analyze their surface composition. XPS survey and high resolution spectra (Ti 2p, O 1s, and C 1s) are presented from three commercially available dental implants, all manufactured by machining but with different post treatments (grit blasting, cleaning, sterilizing, and packaging). Comparison is made with a TiO2single crystal (rutile (110)) reference sample, and with Ti andTi6Al4Vfoils prepared by the following treatments commonly used for titanium biomaterials: ASTM F86/B600 passivation, electropolishing in perchloric acid based electrolyte, anodization in sulfuric acid and phosphoric acid, and glow discharge plasma oxidation. Survey spectra from the implants are qualitatively similar but quantitatively different, with Ti, O, and C as the main elements and trace amounts of preparation-specific impurities. The high resolution spectra show differences in oxide composition (varying deviations from pure TiO2stoichiometry), thickness, and carbon overlayer composition. Spectra from the differently prepared Ti and Ti6Al4V foils showed preparation-specific differences mainly with respect to oxide composition, oxide thickness, and trace impurities. For the Ti6Al4V the different preparations lead to various amounts of detected Al. A general difference between the differently prepared Ti andTi6Al4Vfoils was that Al and V were always detected on the latter, but only sporadically on the Ti. These results clearly show that the composition of titanium surfaces varies considerably depending on the surface preparation used. Important implications are: (i) surface preparation and characteristics need to be considered when results from biological studies on Ti surfaces are interpreted and compared, (ii) Ti andTi6Al4Vform oxides with different composition, and (iii) different commercial Ti implants cannota prioribe assumed to have similar surface composition.

ISSN:1055-5269    

DOI:10.1116/1.1247834

出版商:American Vacuum Society    

年代:1996

数据来源: AIP

摘要:

A poly(tetramethylene oxide) [PTMO] based polyetherurethaneurea (PEUU), produced by Polymer Technology Group Inc. (Emeryville, CA) as a Primary Reference Material, was spin-cast from a 3% (w/v) DMAc solution onto a glass cover slip. The polymer coating was analyzed at ambient temperature by XPS using a 55° take-off angle. An elemental survey scan shows the presence of C, N, and O (no trace elements were detected). The C 1sspectrum shows a nearly equal concentration of ether and hydrocarbon environments, suggesting that surface localization of the PTMO soft segment is occuring. A broadened peak at higher binding energy (~289.1 eV) is indicative of the presence of both urea and urethane nitrogens. The N 1speak location suggests that there is a greater contribution from urea groups. The dominant contributors to the O 1sspectra are ether functionalities. The urea and urethane contributions are apparent as high and low binding energy tails but are too small to be resolved accurately.

ISSN:1055-5269    

DOI:10.1116/1.1247809

出版商:American Vacuum Society    

年代:1996

数据来源: AIP

摘要:

Methionine is one of the 20 amino acids, and one of the two sulfur-containing amino acids. Observations of chemical shifts in various constituents of methionine are important in determining its interaction with a surface in a thin film. As such, spectra of bulk films of methionine, as in this work, serve as a baseline for the thin film studies. In this work, an aqueous solution prepared from methionine powder was poured into a recessed sample holder and allowed to dry. This formed a block of methionine approximately 1/4 in. thick. The spectra were acquired at liquid nitrogen temperature. The atomic concentrations measured with XPS agree well with those expected for methionine, assuming the small amount of excess carbon and oxygen is due to adventitious material. Predominantly zwitterionic character is observed in the O 1sand N 1sspectra. A small amount of either neutral species or condensed polypeptide is also observed.

ISSN:1055-5269    

DOI:10.1116/1.1247810

出版商:American Vacuum Society    

年代:1996

数据来源: AIP