Ladislav Cvrček

Sensing of human plasma fibrinogen on polished, chemically etched and carbon treated titanium surfaces by diffractive optical element based sensor

Adsorption of human plasma fibrinogen (HPF) on 6 differently treated titanium samples (polished, polished and etched, and 4 titanium carbide coatings samples produced by using plasma-enhanced chemical vapour deposition (PECVD) method) is investigated by using diffractive optical element (DOE) sensor. Permittivity (susceptibility) change and fluctuation in optical roughness (R(opt)) of treated titanium surface in the presence of background electrolyte without and with HPF molecules are sensed by using DOE sensor and optical ellipsometry. Correlation between transmitted light and thickness of molecule layer was found. The findings allow to sense temporal organization and severity of adsorption of nano-scale HPF molecules on polished, on polished and etched, and on titanium carbide surface.

Optical Sensing of Attached Fibrinogen on Carbon Doped Titanium Surfaces

The adsorption/desorption of Human Plasma fibrinogen (HPF) molecules on biosurfaces was measured in spectroscopic cuvette by a diffractive optical element- (DOE-) based sensor. To characterize the surfaces, the basic parameters as surface tension was obtained by sensing of a contact angle of water droplet and dielectric constant was measured by ellipsometry in the absence of HPF molecules. It was observed a significant correlation between the adsorption ability of HPF molecules (sensed by DOE on the basis of the changes in optical roughness () of studied surface in the absence and presence of HPF molecules), and dielectric constant (measured by ellipsometry) of differently treated titanium surfaces, where the permittivity and dielectric loss have the known linear relation. These findings with carbon-treated biomaterial surfaces can help us to understand mechanisms behind attachment of HPF molecules on biomaterial surfaces to realize and extend variety of implants for hard tissue replacement.

Growth of a TiNb adhesion interlayer for bioactive coatings

Surface bioactivity has been under intensive study with reference to its use in medical implants. Our study is focused on coatings prepared from an electroactive material which can support bone cell adhesion. Until now, hydroxyapatite films have usually been utilized as a chemically-active surface agent. However, electrically-active films could set a new direction in hard tissue replacement. As a base for these films, it is necessary to prepare an intermediate film, which can serve as a suitable barrier against the possible diffusion of some allergens and toxic elements from the substrate. The intermediate film also improves the adaptation of the mechanical properties of the basic material to an electroactive film. The aim of our work was to select an implantable and biocompatible material for this intermediate film that is suitable for coating several widely-used materials, to check the possibility of preparing an electroactive film for use on a material of this type, and to characterize the structure and several mechanical properties of this intermediate film. TiNb was selected as the material for the intermediate film, because of its excellent chemical and mechanical properties. TiNb coatings were deposited by magnetron sputtering on various substrates, namely Ti, Ti6Al4V, stainless steel, and bulk TiNb (as standard), and important properties of the layers, e.g. surface morphology and surface roughness, crystalline structure, etc., were characterized by several methods (SEM, EBSD, X-ray diffraction, nanoindentation and roughness measurement). It was found that the structure and the mechanical properties of the TiNb layer depended significantly on the type of substrate. TiNb was then used as a substrate for depositing a ferroelectrically active material, e.g., BaTiO3, and the adhesion, viability and proliferation of human osteoblast-like Saos-2 cells on this system were studied. We found that the electroactive BaTiO3 film was not only non-cytotoxic (i.e. it did not affect the cell viability). It also enhanced the growth of Saos-2 cells in comparison with pure TiNb and with standard tissue culture polystyrene wells, and also in comparison with BaTiO3 films deposited on Ti, i.e. a material clinically used for implantation into the bone.

Cytocompatibility of implants coated with titanium nitride and zirconium nitride.

INTRODUCTION The positive cell response to the implant material is reflected by the capacity of cells to divide, which leads to the tissue regeneration and osseointegration. Technically pure titanium and its alloys are mostly used for implant manufacturing. These alloys have the adequate mechanical, physical and biological properties; nevertheless, the superior biocompatibility of bioceramics has been proven. With the arrival of new coating techniques, surface modification of materials used for implants has become a widely investigated issue. METHODS The paper studied properties of titanium nitride (TiN) and zirconium nitride (ZrN) coatings deposited by PVD (Physical Vapour Deposition). Coatings were applied to substrates of pure titanium, Ti6Al4V, Ti35Nb6Ta titanium alloys and CoCrMo dental alloy. Different treatments of substrate surfaces were used: polishing, etching and grit blasting. Cytocompatibility tests assessed the cell colonization and their adherence to substrates. RESULTS AND CONCLUSION Results showed that TiN layers deposited by PVD are suitable for coating all substrates studied. The polished samples and those with TiN coating exhibited a higher cell colonization. This coating technique meets the requirements for the biocompatibility of the implanted materials; furthermore, their colour range solves the issue of red aesthetics in oral implantology as the colour of these coatings prevents titanium from showing through the gingiva. This is one the most important criteria for the aesthetic success of implant therapy (Tab. 5, Ref. 18).

Sensing of parameters behind attachment of human plasma fibrinogens on carbon doped titanium surfaces: an optical study

Polished titanium surface and four differently carbon doped titanium surfaces are investigated to characterize adsorption and desorption of human plasma fibrinogen (HPF) molecules. The surface tension and surface energy of carbon doped titanium and other comparative titanium surfaces used in the experiments were observed by measuring optically the contact angle of water droplet on the treated surfaces. The dielectric constant of each bulk surface was measured utilizing ellipsometry in dry environment. Whereas the temporal adsorption or desorption of HPF molecules on test surfaces in background electrolyte with and without HPF molecules were measured using an optical correlator, which utilizes a diffractive optical element (DOE) in non-contact domain. The optical correlator operates in coherent and in non-coherent mode, which allows sensing of optical path differences providing information on the optical roughness (Ropt), contrary to the mechanical roughness obtained from atomic force microscope (AFM) profilometer, and reflectance of the surfaces immersed into a liquid. The knowledge of the parameters helps us to understand mechanisms behind attachment of HPF molecules on biomaterial surfaces in hard tissue replacement.

Characterization of TiNb Films on Ti Alloys for Hard Tissue Replacement

We present here a study of coatings prepared from β-Ti binary alloy Ti-39wt%Nb, a promising metallic material. TiNb is a highly corrosion-resistant and non-toxic material that is potentially applicable as a biomaterial. TiNb coatings can be prepared on substrates of widely-used materials, and promise not only improved properties but also a less high price of potential TiNb implants. A TiNb film can also be used as a barrier for limiting the potential diffusion of some allergens and toxic elements from the substrate to the surface, which can be influenced by layer properties. We deposited thin layers of TiNb by magnetron sputtering, which provides excellent layer properties in applications. These layers were prepared on substrates made from Ti, Ti alloys (Ti39Nb and Ti6Al4V) and stainless steel AISI316. The aim of our work was to characterize the structure and the mechanical properties of the layers, in dependence on the type of substrate, for application as coatings for medical implants.

On the analysis of optical signals from Ti35Nb6Ta and Ti6Al4V surfaces

Chemical components and initial optical responses of Ti35Nb6Ta alloy are reported. Polished titanium and other titanium alloy Ti6Al4V served as reference surfaces. The chemical composition was determined with an X-ray photoelectron spectroscope (XPS) for the surfaces as well as for water, phosphate buffered saline (PBS) and for human plasma fibrinogen (HPF in PBS) exposed surfaces. The reflectance of the surfaces was modeled utilizing Bruggemans model, to evaluate the optical changes that the chemical reaction of each liquid can produce. After the model, a diffractive optical element (DOE) based sensor was used to determine the temporal optical signal from the sample surfaces. The coherent and non-coherent signals gathered with DOE sensor were compared to the reflectance model. Exposing to the liquids showed surface oxidation, which could produce lowered reflectance of the surface. The model and the initial temporal responses showed similarities in non-coherent reflectance.

Plasma Modified Polymeric Materials for Implant Applications

Abstract Polymeric materials are widely used in orthopedics and traumatology where they have an irreplaceable role in the construction of implants. Unlike metals and ceramics, polymers have a low elastic modulus close to that of cortical bone. Bulk properties together with surface, chemical, and biological properties play a crucial role with regards to the biomedical polymers. However, due to the variability of the polymeric implant applications, the large amount of different polymer types, the variability of their properties and chemistry and, last but not least, many possible methods of their treatment to reach or improve the demanded properties, the polymers used in implant applications are a complex and complicated topic. Plasma surface treatment methods provide independent modification possibilities to the surface and biological properties without any alteration or degradation to the bulk (mechanical) properties. The required biological, chemical, and surface properties of the polymer-based implants will be briefly described including an overview of the plasma methods for the surface treatment of polymeric materials. Afterwards, we will also focus on plasma-modified polymer implants used in various medical applications.