Evaluation Of Surface Modification Research Articles

Surface Modification of Artificial Implants by Hybrid Nanolayers: Antimicrobial Surface Finishing and Strength Tests

Introduction: The aim of this work was the evaluation of surface modification in surgery of normally used hernia implants and thus improving their antimicrobial properties. The modification consisted of applying hybrid nanolayers with immobilized antiseptic substances (metal cations of Ag, Cu, and Zn) by sol-gel method which ensures prolonged effect of these substances and thus enables a greater resistance of the implant towards infection. In this work, attention is drawn to the issue of applying hybrid nanolayers, activation of mesh surfaces by physical plasma modification or ultraviolet C (UV C) radiation, and influence of these modifications on the mechanical properties of the final meshes. Next work will continue concentrating on the issue of antimicrobial efficacy and eventual toxicity of the prepared layers. Materials and Methods: Present-day materials of the most commonly used types of implants for reconstruction of the abdominal wall in surgery (polypropylene, polyester, polyvinylidenefluoride) were tested. Optimum conditions of application of nanolayers by sol-gel method and their thermal stabilization were examined first. Surface modification was verified by scanning electron microscope. The surface of implants was first activated for better adhesion by plasma treatment or UV radiation after preliminary tests. Maximum strength and ductility after activation and hybrid nanolayer modification were objectively measured on a universal Testometric tensile testing machine. Results: The results of surface activation of the meshes (by both plasma treatment or UV C radiation) provided similar and satisfactory results, and particular conditions differed based on the type of material of the mesh. Usage of antimicrobial sol AD30 diluted by isopropyl alcohol in 1:1 proportion appear to be optimal. All tested cases of meshes activated by plasma treatment or UV C radiation and with applied nanolayer concluded in a slight reduction of mechanical properties in modified meshes in comparison with the original ones. However, a slight reduction of test values was not of clinical importance. Conclusion: It was verified that surface modification of implants by sol-gel method is effective and technically possible, providing hopeful results.

CARD25: Computational Fluid Dynamics Evaluation of Surface Modification to Improve Endothelial Retention on Blood-wetted Artificial Organs

CARD25: Computational Fluid Dynamics Evaluation of Surface Modification to Improve Endothelial Retention on Blood-wetted Artificial Organs

Antimicrobial potential and osteoblastic cell growth on electrochemically modified titanium surfaces with nanotubes and selenium or silver incorporation

Titanium nanotube surfaces containing silver, zinc, and copper have shown antimicrobial effects without decreasing osteoblastic cell growth. In this in-vitro study we present first results on the biological evaluation of surface modifications by incorporating selenium and silver compounds into titanium-dioxide (TiO2) nanotubes by electrochemical deposition. TiO2-nanotubes (TNT) and Phosphate-doped TNT (pTNT) were grown on the surface of Ti6Al4V discs by anodization. Hydroxyapatite (HA), selenium (Se) and silver (Ag) compounds were incorporated by electrochemical deposition. Colony forming units of Staphylococcus epidermidis (DSM 3269) were significantly decreased in SepTNT (0.97 ± 0.18 × 106 CFU/mL), SepTNT-HA (1.2 ± 0.39 × 106 CFU/mL), AgpTNT (1.36 ± 0.42 × 106 CFU/mL) and Ag2SepTNT (0.999 ± 0.12 × 106 CFU/mL) compared to the non-modified control (2.2 ± 0.21 × 106 CFU/mL). Bacterial adhesion was calculated by measuring the covered area after fluorescence staining. Adhesion was lower in SepTNT (37.93 ± 12%; P = 0.004), pTNT (47.3 ± 6.3%, P = 0.04), AgpTNT (24.9 ± 1.8%; P < 0.001) and Ag2SepTNT (14.9 ± 4.9%; P < 0.001) compared to the non-modified control (73.7 ± 11%). Biofilm formation and the growth of osteoblastic cells (MG-63) was observed by using Crystal Violet staining. Biofilm formation was reduced in SepTNT (22 ± 3%, P = 0.02) and Ag2SepTNT discs (23 ± 11%, P = 0.02) compared to the non-modified control (54 ± 8%). In comparison with the non-modified control the modified SepTNT-HA and pTNT surfaces showed a significant higher covered area with osteoblastic MG-63-cells. Scanning electron microscope (SEM) images confirmed findings regarding bacterial and osteoblastic cell growth. These findings show a potential synergistic effect by combining selenium and silver with titanium nanotubes.

Evaluation of surface modification in a steel track for the rubber tyred Metro

The rubber tyred metro is a very popular transportation system in some countries, like in Mexico City where 12 lines transport around 5.5 million people every day. The rubber tyre rolls over a steel track subjected under different sources of contamination. Firstly, the rubber tyre accumulates contaminants all over the tread tyre, such as: oil, water, tyre debris, wear particles from the braking and electrical systems, garbage from platforms and steel debris among others. Due to these facts, contamination problems and the rainy season, the metro system suffers severe problems of adhesion. Dangerously, the trains present skidding and slipping problems. The operator must approach and leave the station at very low velocity to prevent accidents. This problem causes delays in the system transportation and discomfort. As a remedy, to reduce the low adhesion, technicians from the metro system have machined grooves on the steel track, however the problem has not been considerably reduced. This work aims to improve the coefficient of friction (CoF) machining the steel track surface with different macro textures. Tests were carried out by using a pendulum friction tester in laboratory. The values indicated an increase in the friction because the grooves help to evacuate water on both sides of the steel track. In addition, the wear rate of some pads from the pendulum increased, indicating a potential increase of wear of rubber tyres due to texturing.

Evaluation of Surface Modification of PA 2200 Parts Made by Selective Laser Sintering Process

Cellular adhesion on surface structures from PA 2200 made through Selective Laser Sintering (SLS) process can be improved by modifying the parts surface. In this paper, different methods for surface modification are presented. The PA 2200 samples were immersed in six different solvents. SEM images and surface roughness tests were performed in order to evaluate the surface modification both for the control group and for the tested groups. The obtained results clearly show that there is a significant difference between the roughness of the control (untreated) surface and each of the treated surfaces. Modifying by immersion, of the PA 2200 structures produced by Selective Laser Sintering process, brings original approaches concerning the use of those procedures in the increase of the surfaces quality.

Surface modifications and oxidative degradation in MPC-grafted highly cross-linked polyethylene liners retrieved from short-term total hip arthroplasty.

Several studies reported that highly crosslinked polyethylene (HXLPE) have resulted in reduced wear in total hip arthroplasty. Beyond those studies, HXLPE hip liners grafted with 2-methacryloyloxyethyl phosphorylcholine (MPC) on their bearing surface were extensively studied in vitro and then commercialized as a new generation of artificial hip joints. The present study reports for the first time results about the evaluation of surface modification and oxidative degradation in retrieved the MPC grafted liners. The findings of this investigation clearly show that the MPC layer has been peeled off on the bearing surface of the liner main wear zone although the MPC layer remained on the surface of the rim zones. Furthermore, we assessed the microstructural modifications and the oxidation drifts that occurred in vivo in the hip joints despite the presence of the MPC layer.

Evaluation of surface modification by electrokinetic measurements

For a long time, measurements of the electrokinetic potential have been used in colloid chemistry mainly for the calculation of electrostatic interaction forces in colloid systems. Moreover, electrokinetic measurements are increasingly successful in characterising solid surfaces. Studies of the effects of pH, surface-active agents, etc. on the electrokinetic potential give valuable information about the nature of solid surfaces. According to Jacobasch [Prog. Org. Coat. 17 (1989) 115], it is possible to distinguish between dissociation and adsorption processes. We are also able to recognise chemical reactions on the surface during measurement. Electrokinetic properties of different polyformamidines should give us an idea about the chances of this method. While electrokinetic properties of colloidal particles have been widely investigated by means of electrophoresis, the electrokinetic characterisation of the surface of macroscopic specimens is still rather uncommon. Indeed, the use of a commercial electrokinetic analyser (EKA) streaming potential measurement apparatus (Anton Paar KG, Graz, Austria) allows the rapid and reproducible measurement of streaming potential, including those of plates and sheets. By means of these investigations, we are able to tackle problems of adhesion of coatings on polymers. This was already demonstrated at the influence of different finishing methods like oxygen plasma treatment or flame treatment on the surface of polypropylene rubber blends [Prog. Org. Coat. 26 (1995) 131; J. Adhes. Sci. Technol. 9 (1995) 327]. By creating special conditions, we succeeded in measuring streaming potentials on metal surfaces, as shown by the example of Al-sheets. With the help of these measurements, different surface treatments were determined.

Surface characterisation of NH 3 plasma treated polyamide 6 foils

Nitrogen-containing plasmas are widely used to improve wettability, printability, bondability, and biocompatibility of polymer surfaces. Plasma-treatments fed with NH 3 give rise to N-functionalities, such as amino (NH 2), imino (CHNH), cyano (CN) and others on polymers, plus oxygen-containing groups due to post-plasma atmospheric oxidation. This work deals with NH 3 plasma treatment of PA 6 foils and the evaluation of surface modification as a function of treatment time. The introduced functionalities were observed by streaming potential measurements (surface charge), X-ray photoelectron spectroscopy analysis (nature of introduced functionalities), atomic force microscopy (surface topography), and contact angle measurement (assessment of treatment effect). The results show that the introduction of N-containing groups is increasing with longer treatment time only to a certain extent where the negative effect of surface destruction prevails over the positive effect of introduction of functional groups. The treatment causes a shift of the isoelectric point (IEP) toward pH of 6.2 as compared to 4.2 found for the untreated foil. If the treatment time is longer than 1 min the IEP is shifted to lower pH, the number of amino groups on the surface is reduced and the contact angle is increased.

IGC Characterization of PMMA Grafted onto CTMP Fiber

Abstract Inverse Gas Chromatography (IGC) was used to characterize chemithermomechanical pulp (CTMP) wood fiber surfaces modified by polymer grafting. From the retention times at infinite dilution over a range of temperatures, the differential heat of adsorption, ΔHoA, the standard free energy, ΔGoA, and the standard entropy of adsorption, ΔSoA, have been determined for the n-alkanes vapors C8-C11 on CTMP wood fibers grafted with poly(methylmethacrylate) (PMMA) at various polymer loadings (PL). The dispersive component of the surface free energy γLS (London) has also been calculated by using a method based on the increment of ΔGoA per CH2 group. Comparison of results for the original material, CTMP and PMMA, with those of the grafted fibers has allowed the evaluation of surface modification. Grafted samples at high PL show values of ΔHoA, ΔGoA, and γLS approaching those of the pure PMMA indicating a high density of polymer chains grafts on the CTMP wood fiber.

High-loading effect of surface-modified inorganic particles in polymer materials

Recently fine-particle technology has been extending its application not only to existing multiphase metals, paint and coatings, but also to other wider industrial fields (such as polymers, ceramics, etc.). In the polymer industries, inorganic particles (mica, talc, calcium carbonate, etc.) are combined to polymer materials in order to improve the stiffness and thermal stability, but the lack of affinity at the interface between particles and the polymer matrix causes a reduction of the mechanical properties and increases the melt viscosity of the composites. Various surface modifications of inorganic particles have therefore been undertaken in order to improve the affinity of the interface between both phases [1-7]. The ceramics industry requires new technology developments such as (a) the evaluation of surface modification for ceramic powders and their sintering performance and (b) high-loading of ceramic powders for the preparation of injection-moulding material for ceramic products [8, 9]. As mentioned above, fineparticle loading technology, evaluation of the particle surface modification, interactive particle-particle forces and the role of the particle-polymer interface are becoming an important technology which is essential for the development and design of composite materials. Based on the above considerations, the high-loading method of inorganic particles in a polymer matrix has been tried and the relationship between particle properties (particle size, size distribution and surface modification) and the properties of particle-filled polymer (the flux rate of the composites and maximum particle loading rate) was investigated in this study. Isotactic polypropylene (PP; Showalomer SA710 from Showa Denko Co. Ltd, [r/] = 1.78 dl g ~ in tetralin at 135°C) was used as the polymer base resin. Calcium carbonate (CaCO3, density 2.7 g cm-3; Bifoku Funka Co. Ltd) and aluminium oxide (A1203, density 4.0 g cm 3; Showa Keikinzoku Co. Ltd) were used as particles as shown in Table I. The surface modifiers for TABLE I Particle properties of CaCO 3 and AI203 Mean particle Surface area a*-value size 0zm) (m2g 1)