One of the main challenges in endoprosthesis surgeries are implant-associated infections and aseptic-loosenings, caused by wear debris. To combat these problems, the requirements to surfaces of endoprostheses are wear-resistance, low cytotoxicity and antimicrobial efficacy. We here present antimicrobial coatings with a smart, adaptive release of metal ions in case of infection, based on ZnO-nanoparticles embedded in diamond-like carbon (DLC). The Zn2+ ion release of these coatings in aqueous environments reacts and adapts smartly on inflammations accompanied by acidosis. Moreover, we show that this increased ion release comes along with an increased toxicity to fibroblastic cells (L929) and bacteria (Staphylococcus aureus subsp. aureus, resistant to methicillin and oxacillin. (ATCC 43300, MRSA) and Staphylococcus epidermidis (ATCC 35984, S. epidermidis). Interestingly, the antimicrobial effect and the cytotoxicity of the coatings increase with a reduction of the pH value from 7.4 to 6.4, but not further to pH 5.4.

The implant-bone interface is the scene of competition between microorganisms and distinct types of tissue cells. In the past, various strategies have been followed to support bony integration and to prevent bacterial implant-associated infections. In the present study we investigated the biological properties of diamond-like carbon (DLC) surfaces containing silver nanoparticles. DLC is a promising material for the modification of medical implants providing high mechanical and chemical stability and a high degree of biocompatibility. DLC surface modifications with varying silver concentrations were generated on medical-grade titanium discs, using plasma immersion ion implantation-induced densification of silver nanoparticle-containing polyvinylpyrrolidone polymer solutions. Immersion of implants in aqueous liquids resulted in a rapid silver release reducing the growth of surface-bound and planktonic Staphylococcus aureus and Staphylococcus epidermidis. Due to the fast and transient release of silver ions from the modified implants, the surfaces became biocompatible, ensuring growth of mammalian cells. Human endothelial cells retained their cellular differentiation as indicated by the intracellular formation of Weibel-Palade bodies and a high responsiveness towards histamine. Our findings indicate that the integration of silver nanoparticles into DLC prevents bacterial colonization due to a fast initial release of silver ions, facilitating the growth of silver susceptible mammalian cells subsequently.

Antibacterial coatings of medical devices have been introduced as a promising approach to reduce the risk of infection. In this context, diamond-like carbon coated polyethylene (DLC-PE) can be enriched with bactericidal ions and gain antimicrobial potency. So far, influence of different deposition methods and ions on antimicrobial effects of DLC-PE is unclear.

The aim of this study was the synthesis of hard and low-abrasive novel implant materials with built-in time-dependent antibacterial properties, which can be tailored by a well-defined time-dependent and finite release of metal ions. We were able to synthesize such smart implant surfaces employing ECR (electron cyclotron resonance)-plasma on typical titanium implant material by transforming a polymer film into diamond-like carbon (DLC) which contains metal nanoparticles as reservoirs for controlled metal ion release. We found that the amount of released antibacterial metal ions is a biexponential function of time with a high release rate during the first few hours followed by a decreased ion release rate within the following days. To describe our experimental findings, we developed a kinetic model assuming that both nanoparticles near the surface and nanoparticles in the DLC bulk contribute to the total amount of ions released with different time constants.

Silver ions (Ag + ) have strong bactericidal effects and Ag-coated medical devices proved their effectiveness in reducing infections in revision total joint arthroplasty. We quantitatively determined the antimicrobial potency of different surface treatments on a titanium alloy (Ti), which had been conversed to diamond-like carbon (DLC-Ti) and doped with high (Ag:PVP = 1:2) and low (Ag:PVP = 1:10 and 1:20) concentrations of Ag (Ag-DLC-Ti) with a modified technique of ion implantation. Bacterial adhesion and planktonic growth of clinically relevant bacterial strains ( Staphylococcus epidermidis, Staphylococcus aureus, and Pseudomonas aeruginosa ) on Ag-DLC-Ti were compared to untreated Ti by quantification of colony forming units on the adherent surface and in the growth medium as well as semiquantitatively by determining the grade of biofilm formation by scanning electron microscopy. (1) A significant (p < 0.05) antimicrobial effect could be found for all Ag-DLC-Ti samples (reduced growth by 5.6–2.5 logarithmic levels). (2) The antimicrobial effect was depending on the tested bacterial strain (most for P. aeruginosa , least for S. aureus ). (3) Antimicrobial potency was positively correlated with Ag concentrations. (4) Biofilm formation was decreased by Ag-DLC-Ti surfaces. This study revealed potent antibacterial effects of Ag-DLC-Ti. This may serve as a promising novel approach to close the gap in antimicrobial protection of musculoskeletal implants.

For an optimal implementation of materials, such as, e.g. medical implants in living environments, a thorough characterization of cell adhesion, kinetics and strength is required, as well as a prerequisite e.g. for bone integration. Here we present a miniaturized (~100 μl) lab-on-a-chip implant hybrid system which allows quantification of cell adhesion under dynamic conditions mimicking those of physiological relevance. Surface acoustic waves are excited and used on optical transparent chips to induce micro acoustic streaming and to create a microfluidic shear spectrum ranging from 0 to ~35 s(-1). We demonstrate its potential for a time-efficient, dynamic screening test of new implant materials using a model of an osseointegration with SAOS-2 cells. The upside-down orientation also allows utilization of the micro reactor on non-transparent materials like titanium and diamond-like-carbon (DLC).

Light propagation is usually reciprocal. However, a static magnetic field along the propagation direction can break the time-reversal symmetry in the presence of magneto-optical materials. The Faraday effect in magneto-optical materials rotates the polarization plane of light, and when light travels backward the polarization is further rotated. This is applied in optical isolators, which are of crucial importance in optical systems. Faraday isolators are typically bulky due to the weak Faraday effect of available magneto-optical materials. The growing research endeavour in integrated optics demands thin-film Faraday rotators and enhancement of the Faraday effect. Here, we report significant enhancement of Faraday rotation by hybridizing plasmonics with magneto-optics. By fabricating plasmonic nanostructures on laser-deposited magneto-optical thin films, Faraday rotation is enhanced by one order of magnitude in our experiment, while high transparency is maintained. We elucidate the enhanced Faraday effect by the interplay between plasmons and different photonic waveguide modes in our system.

In this work TiO2/Si multilayer structures have been grown by sputtering. After rapid thermal annealing in pure inert gas or inert gas with oxygen atmosphere the multilayers have been investigated by high resolution transmission electron microscopy, μ-Raman and dynamic secondary ion mass spectrometry for their structure and anatase/rutile phase composition. It has been found that the photocatalytically more active anatase TiO2 is stabilized and that interdiffusion and chemical reaction processes were strongly hindered up to 1100°C annealing temperature in oxygen containing atmosphere. These findings are of particular importance since only at this high temperature simultaneous formation of embedded Si nanocrystallites can be achieved.

This paper reports the successful reduction of tensile strain in a thin ion-beam-synthesized 3C-SiC(111) layer on silicon. Significant relaxation is achieved by creating a near-interface defect structure containing nanometric voids and dislocation loops by the implantation of He ions and subsequent thermal annealing. The structural features of this defect microstructure are investigated by transmission electron microscopy. High-resolution X-ray diffraction in a parallel beam configuration is used to quantify the strain state of the top SiC layer. Further annealing experiments were carried out in order to emulate typical process conditions for the growth of wide-bandgap semiconductors like, for example GaN. It is found that prolonged annealing at elevated temperatures leads to coarsening of the voids and to a much less efficient strain reduction. We show that this issue can be resolved by the co-implantation of oxygen to form highly thermally stable cavity/extended defect structures. The technique presented here may be useful for a variety of other thermally mismatched bulk/thin film couples as well. (C) 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

Depth profiles of the radiation damage produced by 4 MeV Ag ions in Si(111) at temperatures of 210-450 K are studied by optical reflectivity depth profiling and TEM for doses between 1012 and 1015 Ag/cm2. For high implantation temperatures, the depth of maximum damage is shown to be dose dependent. Point defect diffusion is shown to result in long tails of defect depth profiles. High-temperature amorphization is observed to proceed via the formation and bridge-like coalescence of isolated amorphous volumina. The damage at the depth of the maximum in the nuclear stopping power is described as a function of dose and temperature by the Hecking model. The model parameters and a comparison with those obtained for lighter ions reflect the particular properties of heavy ion collision cascades.

Diamond-like carbon (DLC) is known to be a versatile coating material for biomedical applications like endoprosthesis and dental implants. It provides mechanical robustness and cell-compatibility at the same time. To even more broaden this range of beneficial properties, it is tried to add antibacterial properties by incorporating silver nanoparticles. In this paper we discuss a novel approach to producing such coatings, capable of circumventing typical drawbacks of conventional deposition methods. To investigate the potential antibacterial properties an in vitro adhesion assay was created. Thereto Streptococcus sanguinis (DSM 20068) responsible for initial biofilm formation in peri-implant infection has been used. The results clearly show that silver nanoparticles are crucial for the antimicrobial effect as long as they are incorporated in the DLC-surface so that the adhering bacteria are directly exposed.

In this work the effect of elliptical beam shapes on cutting performance of silicon is studied experimentally using a Diode Pumped Solid State Q-switched UV laser operating at the wavelength of 355 nm. Elliptical beams are investigated by varying scanning speed, repetition rate and average output power. It is shown that a short elliptical beam with 6×230 μm dimension forms a deeper groove at higher cutting speed and lower average output power compared to a longer elliptical beam. A numerical model of the laser cutting process is also described. Some validation results for single and multi-pulse cutting are shown.

The phase and element composition, microhardness of a 'Ti/steel' system mixed under the action of compression plasma flows have been investigated in this work. Non-Rutherford backscattering, X-ray diffraction, scanning electron microscopy and Vickers microhardness measurements were used for samples characterization. The findings showed that the change of the coating thickness in the range of 0.5-5 mu m resulted in the Ti concentration change in the mixed layer from 4 to 30 at.-%. The increase of the titanium content was accompanied by the formation of a supersaturated alpha-Fe(Ti) solid solution, Fe2Ti and TiN. The phase composition changes and quenching effect led to the surface layer microhardness increase.

We review briefly reports on lasing in different kinds of ZnO nanostructures ranging from clusters to pillars, tetrapods, and belts. Then detailed studies on individually in-situ accessible, well-faceted upright pillars grown on a metal interlayer on silicon substrate are presented. We observe in cathodoluminescence directly ultraviolet light standing wave resonator modes, and tinder pulsed excitation lasing activity based on (e,h) plasma recombination.

The selective formation of large-scale graphene layers on a Rh-YSZ-Si(111) multilayer substrate by a surface-induced chemical growth mechanism is investigated using low-energy electron diffraction, X-ray photoelectron spectroscopy, X-ray photoelectron diffraction, and scanning tunneling microscopy. It is shown that well-ordered graphene layers can be grown using simple and controllable procedures. In addition, temperature-dependent experiments provide insight into the details of the growth mechanisms. A comparison of different precursors shows that a mobile dicarbon species (e.g., C(2)H(2) or C(2)) acts as a common intermediate for graphene formation. These new approaches offer scalable methods for the large-scale production of high-quality graphene layers on silicon-based multilayer substrates.

Ion beam assisted deposition (IBAD) allows a biaxial texturing of oxide layers on polycrystalline or amorphous substrates. Even the best layers still contain an in-plane angular spread of about 4 degrees. We report here a method to grow Ir films oil top of with a factor of 5 lower misorientation. It is shown that the huge texture improvement involves a massive these oxide layers realignment of the iridium islands and in orientation averaging process. Heteroepitaxial diamond was successfully deposited oil the Ir/IBAD-MgO multilayer stacks. The described texture improvement by irichum layers provides a general concept towards single crystal growth on arbitrary substrates. [DOI: 10.1143/JJAP.47.8925]

Carbides stand out because of their high hardness and wear-resistance. Thus these materials are often discussed for coatings of machine tools etc. Within this work Boron Carbide (B4C) and Carbide (C) thin films were deposited on Si (100) substrates by pulsed-laser deposition technique. In order to improve the wear-resistance of the deposited films, we introduced a new working technique including the application of a second excimer laser in a special working mode. Thereby one laser was used to ablate the carbide material from a target and to deposit the material on the substrate. The light of the second laser was directed directly onto the substrate in order to modify the ablated material. We report on details for film deposition and film properties determined by Scanning Electron Microscope, Energy Dispersive X-Ray Spectroscopy, X-Ray Diffraction, Rutherford Backscattering, Raman Spectroscopy and tribological experiments.

In this paper, we present extensive investigations of the growth of bismuth-substituted iron garnet Bi3Fe5O12 (BIG) on (001)-, (111)- and (110)-oriented gadolinium gallium garnet Gd3Ga5O12 (GGG) and doped GGG (SGGG, S*GGG) substrates by pulsed laser deposition. The growth has been studied by the use of in-situ reflecting high-energy electron diffraction, atomic force microscopy, scanning electron microscopy and X-ray diffraction. We found 3D island growth to be the dominant growth mode for the BIG films. Additionally, we present a special technique to create very large BIG growth islands. This method involves the use of a metallic bismuth iron ablation target and partially shielding the substrate during deposition. The growth islands have a characteristic geometry depending on the cut of the substrate. We could explain their shapes by the assumption that growing BIG tends to form {110} facets.

Silicon nanowires (SiNWs) were grown on Si(100) and Si(111) substrates by chemical vapour deposition (CVD) via the vapour–liquid–solid (VLS) mechanism with small gold particles used as seeds. In order to control the diameter of nanowires, their density on the substrate and their orientation we controlled the size and the distribution of Au seed particles. This was accomplished using nanosphere lithography (NSL) by which regular arrays of Au nanoparticles can be generated. This allowed us to grow single-crystalline SiNWs perpendicular to the surface of Si(111) substrates. The SiNWs and their Au caps were studied with respect to their morphology and composition using TEM, HREM and EFTEM methods. Clusters of Au are observed along the surface of SiNWs and the existence of a thin Si film on gold particles capping the SiNWs is demonstrated.