Utilizing Constant Energy Difference between sp-Peak and C 1s Core Level in Photoelectron Spectra for Unambiguous Identification and Quantification of Diamond Phase in Nanodiamonds.

The modification of nanodiamond (ND) surfaces has significant applications in sensing devices, drug delivery, bioimaging, and tissue engineering. Precise control of the diamond phase composition and bond configurations during ND processing and surface finalization is crucial. In this study, we conducted a comparative analysis of the graphitization process in various types of hydrogenated NDs, considering differences in ND size and quality. We prepared three types of hydrogenated NDs: high-pressure high-temperature NDs (HPHT ND-H; 0-30 nm), conventional detonation nanodiamonds (DND-H; ~5 nm), and size- and nitrogen-reduced hydrogenated nanodiamonds (snr-DND-H; 2-3 nm). The samples underwent annealing in an ultra-high vacuum and sputtering by Ar cluster ion beam (ArCIB). Samples were investigated by in situ X-ray photoelectron spectroscopy (XPS), in situ ultraviolet photoelectron spectroscopy (UPS), and Raman spectroscopy (RS). Our investigation revealed that the graphitization temperature of NDs ranges from 600 °C to 700 °C and depends on the size and crystallinity of the NDs. Smaller DND particles with a high density of defects exhibit a lower graphitization temperature. We revealed a constant energy difference of 271.3 eV between the sp-peak in the valence band spectra (at around 13.7 eV) and the sp3 component in the C 1s core level spectra (at 285.0 eV). The identification of this energy difference helps in calibrating charge shifts and serves the unambiguous identification of the sp3 bond contribution in the C 1s spectra obtained from ND samples. Results were validated through reference measurements on hydrogenated single crystal C(111)-H and highly-ordered pyrolytic graphite (HOPG).

On the Origin of Reduced Cytotoxicity of Germanium-Doped Diamond-Like Carbon: Role of Top Surface Composition and Bonding.

This work attempts to understand the behaviour of Ge-induced cytotoxicity of germanium-doped hydrogen-free diamond-like carbon (DLC) films recently thoroughly studied and published by Jelinek et al. At a low doping level, the films showed no cytotoxicity, while at a higher doping level, the films were found to exhibit medium to high cytotoxicity. We demonstrate, using surface-sensitive methods-two-angle X-ray-induced core-level photoelectron spectroscopy (ARXPS) and Low Energy Ion Scattering (LEIS) spectroscopy, that at a low doping level, the layers are capped by a carbon film which impedes the contact of Ge species with tissue. For higher Ge content in the DLC films, oxidized Ge species are located at the top surface of the layers, provoking cytotoxicity. The present results indicate no threshold for Ge concentration in cell culture substrate to avoid a severe toxic reaction.

In Vitro Bioactivity Test of Real Dental Implants According to ISO 23317.

PURPOSE: The goal of this study was to compare the in vitro bioactivity in simulated body fluid (SBF) of commercially available dental implants. MATERIALS AND METHODS: Bioactivity, according to ISO 23317, of commercially available dental implants with various surface modifications (BIO-surface, SLA, SLActive, TiUnite, and OsseoSpeed) was tested in SBF for 1 and 3 weeks. Surface characterizations, especially calcium and phosphorus surface content before and after the immersion in SBF, were performed. The effect of surface treatment on bioactivity was studied. RESULTS: Differences between surfaces before immersion in SBF were confirmed by Raman spectroscopy, x-ray photoelectron spectroscopy (XPS), energy-dispersive x-ray spectroscopy (EDX), and scanning electron microscope (SEM) analysis. Calcium and phosphorus surface content was increasing within the tested period in the case of two (BIO-surface and SLActive) of the five tested dental implants. Calcium-phosphate precipitation was observed by SEM, XPS, EDX, and x-ray micro­diffraction (µ-XRD) analysis. CONCLUSION: Two (BIO-surface from LASAK and SLActive from Straumann) of the five tested dental implants were found to be bioactive, according to ISO 23317. Although it is difficult to unambiguously determine the properties that have influence on the hydroxyapatite precipitation rate, multiple properties that the two surfaces have in common were found.

Adhesion and differentiation of Saos-2 osteoblast-like cells on chromium-doped diamond-like carbon coatings.

Diamond-like carbon (DLC) thin films are promising for use in coating orthopaedic, dental and cardiovascular implants. The problem of DLC layers lies in their weak layer adhesion to metal implants. Chromium is used as a dopant for improving the adhesion of DLC films. Cr-DLC layers were prepared by a hybrid technology, using a combination of pulsed laser deposition (PLD) from a graphite target and magnetron sputtering. Depending on the deposition conditions, the concentration of Cr in the DLC layers moved from zero to 10.0 at.%. The effect of DLC layers with 0.0, 0.9, 1.8, 7.3, 7.7 and 10.0 at.% Cr content on the adhesion and osteogenic differentiation of human osteoblast-like Saos-2 cells was assessed in vitro. The DLC samples that contained 7.7 and 10.0 at.% of Cr supported cell spreading on day 1 after seeding. On day three after seeding, the most apparent vinculin-containing focal adhesion plaques were also found on samples with higher concentrations of chromium. On the other hand, the expression of type I collagen and alkaline phosphatase at the mRNA and protein level was the highest on Cr-DLC samples with a lower concentration of Cr (0-1.8 at.%). We can conclude that higher concentrations of chromium supported cell adhesion; however DLC and DLC doped with a lower concentration of chromium supported osteogenic cell differentiation.

Bonding and bio-properties of hybrid laser/magnetron Cr-enriched DLC layers.

Chromium-enriched diamond-like carbon (DLC) layers were prepared by a hybrid technology using a combination of pulsed laser deposition (PLD) and magnetron sputtering. XRD revealed no chromium peaks, indicating that the layers are mostly amorphous. Carbon (sp(2) and sp(3) bonds) and chromium bonds were determined by XPS from C 1s, O 1s, and Cr 2p photoelectron peaks. Depending on the deposition conditions, the concentration of Cr in DLC layers moved from zero to 10 at.% for as-received sample surfaces, and to about 31 at.% after mild sputter-cleaning by argon ion cluster beam. It should be noted that the most stable Cr(3+) bonding state is in Cr2O3 and Cr(OH)3, and that there is the toxic Cr(6+) state in CrO3. The surface content of hexavalent chromium in the Cr 2p3/2 spectra is rather low, but discernible. The population density of Saos-2 cells was the highest in samples containing higher concentrations of chromium 7.7 and 10 at.%. This means that higher concentrations of chromium supported the cell adhesion and proliferation. In addition, as revealed by a LIVE/DEAD viability/cytotoxicity kit, the cells on all Cr-containing samples maintained high viability (96 to 99%) on days 1 and 3 after seeding. However, this seemingly positive cell behavior could be associated with the risk of dedifferentiation and oncogenic transformation of cells.

Deep Neck infections of Odontogenic Origin and Their Clinical Significance. A Retrospective Study from Hradec Králové, Czech Republic.

INTRODUCTION: Cellulitis remains a very serious disease even today. Mortality, which varied between 10-40%, has been reduced owing to the standard securing of airway patency and use of an appropriate surgical treatment approach. MATERIALS AND METHODS: A total of 195 patients were hospitalised for cellulitis at the University Hospital in Hradec Králové during 2007-2011. The following parameters were evaluated: age, gender, dependence of incidence of the disease on the season of the year, frequency of attacks of the particular areas and their clinical characteristics, aetiology of the inflammation, types of patient complaints, prevalence of current systemic diseases, results of microbiological and selected laboratory analyses, socio-economic status of the patients, and duration of patient stay at the hospital. Statistical analysis was performed by using Pearson's correlation coefficient, the statistical significance level was p < 0.05. RESULTS: The mean age of the patients was 39.8 years. The group of 195 patients included 108 (55%) males and 87 (45%) females. The mean time between the first symptoms of the disease and admission to the Department was 5 days. From among the 195 patients, 116 (59.5%) were working persons, 79 (40.5%) were non-working (children, students, unemployed persons, women on maternity leave, retired people). The odontogenic origin of the disease was verified in 173 (88.7%) patients. In total, 65 (33.3%) patients had no coinciding complicating systemic disease, 22 (11.3%) patients had diabetes mellitus. The most frequent symptom of cellulitis was painful swelling, found in 194 (99.5%) patients, followed by jaw contracture, found in 153 (78.5%) patients. CONCLUSION: The results are largely very similar to those of previous studies performed in other countries, except that we found no correlation between the prevalence of cellulitis and the socio-economic status, nor have we confirmed Klebsiella pneumoniae sp. as the cause of cellulitis in patients with diabetes mellitus.

Self-assembled anchor layers/polysaccharide coatings on titanium surfaces: a study of functionalization and stability.

Composite materials based on a titanium support and a thin, alginate hydrogel could be used in bone tissue engineering as a scaffold material that provides biologically active molecules. The main objective of this contribution is to characterize the activation and the functionalization of titanium surfaces by the covalent immobilization of anchoring layers of self-assembled bisphosphonate neridronate monolayers and polymer films of 3-aminopropyltriethoxysilane and biomimetic poly(dopamine). These were further used to bind a bio-functional alginate coating. The success of the titanium surface activation, anchoring layer formation and alginate immobilization, as well as the stability upon immersion under physiological-like conditions, are demonstrated by different surface sensitive techniques such as spectroscopic ellipsometry, infrared reflection-absorption spectroscopy and X-ray photoelectron spectroscopy. The changes in morphology and the established continuity of the layers are examined by scanning electron microscopy, surface profilometry and atomic force microscopy. The changes in hydrophilicity after each modification step are further examined by contact angle goniometry.

Chromium-doped DLC for implants prepared by laser-magnetron deposition.

Diamond-like carbon (DLC) thin films are frequently used for coating of implants. The problem of DLC layers lies in bad layer adhesion to metal implants. Chromium is used as a dopant for improvement of adhesion of DLC films. DLC and Cr-DLC layers were deposited on silicon, Ti6Al4V and CoCrMo substrates by a hybrid technology using combination of pulsed laser deposition (PLD) and magnetron sputtering. The topology of layers was studied using SEM, AFM and mechanical profilometer. Carbon and chromium content and concentration of trivalent and toxic hexavalent chromium bonds were determined by XPS and WDS. It follows from the scratch tests that Cr doping improved adhesion of DLC layers. Ethylene glycol, diiodomethane and deionized water were used to measure the contact angles. The surface free energy (SFE) was calculated. The antibacterial properties were studied using Pseudomonas aeruginosa and Staphylococcus aureus bacteria. The influence of SFE, hydrophobicity and surface roughness on antibacterial ability of doped layers is discussed.

Electron supersurface scattering on polycrystalline Au.

Supersurface electron scattering, i.e., electron energy losses and associated deflections in vacuum above the surface of a medium, is shown to contribute significantly to electron spectra. We have obtained experimental verification (in absolute units) of theoretical predictions that the angular distribution of the supersurface backscattering probability exhibits strong oscillations which are anticorrelated with the generalized Ramsauer-Townsend minima in the backscattering probability. We have investigated 500-eV electron backscattering from an Au surface for an incidence angle of 70° and scattering angles between 37° and 165°. After removing the contribution of supersurface scattering from the experimental data, the resulting angular and energy distribution agrees with the Landau-Goudsmit-Saunderson (LGS) theory, which was proposed about 60 years ago, while the raw data are anticorrelated with LGS theory. This result implies that supersurface scattering is an essential phenomenon for quantitative understanding of electron spectra.

Electron spectra line shape analysis of highly oriented pyrolytic graphite and nanocrystalline diamond.

The X-ray excited Auger electron spectroscopy (XAES), X-ray photoelectron spectroscopy (XPS) and elastic peak electron spectroscopy (EPES) methods were applied in investigating samples of nanocrystalline diamond and highly oriented pyrolytic graphite of various C sp(2)/sp(3) ratios, crystallinity conditions and grain sizes. The composition at the surface was estimated from the XPS. The C sp(2)/sp(3) ratio was evaluated from the width of the XAES first derivative C KLL spectra and from fitting of XPS C 1s spectra into components. The pattern recognition (PR) method applied for analyzing the spectra line shapes exhibited high accuracy in distinguishing different carbon materials. The PR method was found to be a potentially useful approach for identification, especially important for technological applications in fields of materials engineering and for controlling the chemical reaction products during synthesis.

Modification of glass fibers to improve reinforcement: a plasma polymerization technique.

OBJECTIVES: This study evaluates the effect of plasma treated E-glass fiber to improve the mechanical properties of acrylic resin denture base material, polymethylmethacrlyate (PMMA). Plasma surface treatment of fibers is used as reinforcement in composite materials to modify the chemical and physical properties of their surfaces with tailored fiber-matrix bonding strength. METHODS: Three different types of monomer 2-hydroxyethyl methacrylate (HEMA), triethyleneglycoldimethylether (TEGDME) and ethylenediamine (EDA) were used in the plasma polymerization modification of glass fibers. A radiofrequency generator was used to sustain plasma in a glass vacuum chamber. Glass fibers were modified at the same glow-discharge power of 25 W and exposure time of 30 min for each monomer. Fibers were incorporated into the acrylic with 1% (w/w) loading except control group. Specimens were prepared using a standard mold of 3 cmx0.5 cmx0.8 cm in dimension with eight specimens in each group. Samples were subjected to a flexural strength test set up at a crosshead speed of 5mm/min. Scanning electron microscopy (SEM) was used to examine the microstructure and X-ray photoelectron spectroscopy (XPS) was used for chemical analysis of the surface. RESULTS: Data were analyzed by means of ANOVA and Duncan's tests. Test results revealed that fiber reinforcement had a significant effect on the flexural strength of the specimens (p<0.05). Among the fiber reinforced groups, plasma treatment with EDA monomer resulted in the most significant increase in flexural strength values (p<0.05). XPS results have shown an increasing number of nitrogenous compounds in EDA treated fibers. The chemical structure of the surface, especially with the increase in nitrogenous compounds could give an idea for the amine film deposition and SEM figures showed an increase in surface roughness. SIGNIFICANCE: The results showed that plasma treatment with EDA monomer was an effective alternative method of increasing the flexural strength of PMMA based denture base polymers through fiber reinforcement.

Coating of zinc ferrite particles with a conducting polymer, polyaniline.

Particles of zinc ferrite, ZnOFe2O3, were coated with polyaniline (PANI) phosphate during the in situ polymerization of aniline in an aqueous solution of phosphoric acid. The PANI-ferrite composites were characterized by FTIR spectroscopy. X-ray photoelectron spectroscopy was used to determine the degree of coating with a conducting polymer. Even a low content of PANI, 1.4 wt%, resulted in the 45% coating of the particles' surface. On the other hand, even at high PANI content, the coating of ferrite surface did not exceeded 90%. This is explained by the clustering of hydrophobic aniline oligomers at the hydrophilic ferrite surface and the consequent irregular PANI coating. The conductivity increased from 2 x 10(-9) to 6.5 S cm(-1) with increasing fraction of PANI phosphate in the composite. The percolation threshold was located at 3-4 vol% of the conducting component. In the absence of any acid, a conducting product, 1.4 x 10(-2) Scm(-1), was also obtained. As the concentration of phosphoric acid increased to 3 M, the conductivity of the composites reached 1.8 S cm(-1) at 10-14 wt% of PANI. The ferrite alone can act as an oxidant for aniline; a product having a conductivity 0.11 S cm(-1) was obtained after a one-month immersion of ferrite in an acidic solution of aniline.