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PubMed2007

Inflammatory response to titanium surfaces with fibrinogen and catalase coatings: an in vitro study.

The aim of the present study was to evaluate the possibility to modulate the early inflammatory response in vitro by coating titanium surfaces with candidate proinflammatory (fibrinogen coated turned titanium "Fib") and antiinflammatory proteins (catalase on top of fibrinogen coated turned titanium "Cat"). Additionally, turned titanium surfaces (Ti) were used as controls. The discs were incubated with human mononuclear cells. Adhered cells were investigated with respect to number, viability, differentiation (acute marker 27E10 vs. chronic marker RM3/1), and cytokine production (TNF-alpha and IL-10), after 24 and 72 h. The results indicated that it is possible to modulate the inflammatory response with protein coatings. However, the strongest inflammatory response, indicated by increased number of adhered cells and release of pro and antiinflammatory mediators, was induced by Cat. Furthermore, the cytokine production on this surface was not sensitive to LPS stimulation. Differentiation measured as the expression of the chronic cell surface marker, dominated after 72 h for all surface modifications and Cat displayed an increased number compared to the others. A decrease in the total number of adhered cells and amounts of TNF-alpha were observed on all surfaces over time. The cell viability was, in general, high for all tested surfaces. In conclusion, the study proved it possible to influence the early inflammatory response in vitro by immobilizing protein coatings to titanium surfaces. However, the catalase surface demonstrated the strongest inflammatory response, and the possibility to selectively use the potent antiinflammatory capacity of catalase needs to be further evaluated.

Catalase↗

PubMed2005

Study of the influence of beta-radiation on the properties and mineralization of different starch-based biomaterials.

In this work, the effects of beta-radiation are assessed, for the first time, on starch-based biodegradable polymers, with the aim of using it as an alternative sterilization process to the previously studied sterilization methods. Different doses of radiation were used in order to investigate the possibility of using this sterilization technique as a treatment to tailor the surface and bulk properties (namely mechanical) of these polymers. The as-treated substrates were characterized by water-uptake measurements and contact angle (theta) measurements. The mechanical properties of the materials were characterized by tensile tests by means of ultimate tensile strength (UTS) and strain at break (epsilon). The fracture of the surfaces was observed by scanning electron microscopy (SEM). Dynamic mechanical analysis (DMA) was also used to characterize the viscolelastic behavior of the irradiated materials. The main effect of sterilization with beta-radiation over the starch-based polymers seems to be a surface modification by an increase of the hydrophilicity. Nevertheless, because beta-radiation did not significantly affect the mechanical properties, it can be regarded as an effective way of modifying the surface for applications were more hydrophilic surfaces are desirable.

Beta Particles↗

PubMed2006

Surface elastic properties of Ti alloys modified for medical implants: a force spectroscopy study.

We report here the first nanoscale surface elasticity measurements on surface-modified titanium alloys using the force spectroscopy mode in scanning force microscopy. Samples of three vanadium-free titanium alloys, Ti-7Nb-6Al, Ti-13Nb-13Zr and Ti-15Zr-4Nb, were investigated. Surface modification of the three alloys was produced by thermal oxidation in air at 750 degrees C for different times, which resulted in the formation of protective oxide layers with different surface composition and morphology. The elastic properties of the surface layers were studied comparatively in the as-received Ti alloys and after the oxidation process using cantilevers with different stiffness to evaluate the influence of the indentation depth. In all cases, Young's modulus of the sample surfaces was found to be lower than 65GPa, and as low as 20GPa for some of the oxidized samples. Variations observed for the three oxidized Ti alloys can be related to the different chemical composition of the outer layers generated for the different oxidation times.

Alloys↗

PubMed2004

The hydrophilization of polystyrene substrates by 172-nm vacuum ultraviolet light.

This paper describes the photochemical surface modification of polystyrene (PS) substrates using vacuum ultraviolet (VUV) light 172 nm in wavelength. We have particularly focused on the effects of atmospheric pressure during VUV irradiation on the obtained surface's wettability and the stability of the wettability, in addition to its chemical structure, morphology, and photooxidation rate. Samples were photoirradiated with VUV light under pressures of 10, 10(3), or 10(5) Pa. Although, in each case, the originally hydrophobic PS surface became highly hydrophilic, the final water-contact angle and photooxidation rate depended on the atmospheric pressure. The samples treated at 10 Pa were less wettable than those prepared at 10(3) and 10(5) Pa due to the shortage of oxygen molecules in the atmosphere. The minimum water-contact angles of the samples treated at 10, 10(3), and 10(5) Pa were about 8 degrees, 0 degrees, and 0 degrees, respectively. With the samples prepared at 10 and 10(3) Pa, photooxidation reactions proceeded in the topmost region closest to the surface, while at 10(5) Pa photooxidation was found to be greatly enhanced in the deeper regions, as evidenced by angle-resolved X-ray photoelectron spectroscopy. Photoetching rates were determined through atomic force microscope observation of microstructured PS samples prepared by a simple mesh-contact method. As estimated from AFM images of the latticed microstructures obtained, the rates of samples prepared at 10(3) and 10(5) Pa were about 1.5 and 1.3 nm/min, respectively. However, no photoetched features were observable on the sample surface prepared at 10 Pa. Hydrophilic stability also varied greatly depending on atmospheric pressure. The hydrophilicity of samples treated at 10 and 10(3) Pa gradually decreased as they were exposed to air. On the other hand, the sample surface prepared at 10(5) Pa showed excellent hydrophilicity even after being left in air for 30 days.

Journal Article↗

PubMed2004

Prolonged circulation of large polymeric nanoparticles by non-covalent adsorption on erythrocytes.

Polymeric nanoparticles have been extensively studied for use as intravascular drug delivery vehicles; however, their applications are limited by rapid clearance from circulation by the reticuloendothelial system (RES). Previous attempts to improve vascular circulation have focused on surface modification using polymers such as poloxamines, poloxamers, and polyethylene glycol, to prevent opsononization. We report on a novel method of prolonging intravascular particle circulation by anchoring the nanoparticles to the surface of red blood cells (RBCs). We hypothesize that particles adhered to RBCs can escape RES clearance due to the ability of RBCs to do so. This method is motivated by the strategy adopted by certain bacteria, for example, hemobartonella, that adhere to RBCs and remain in circulation for several weeks. Prolonged circulation of nanoparticles as large as 450 nm was observed after adsorption on RBCs. Although particles were eventually eliminated from circulation, RBCs were not cleared. RBC-anchored nanoparticles offer a novel approach for intravascular drug delivery and blood pool imaging.

Adsorption↗

PubMed2002

Ketoimino groups as silica surface modifiers.

The presented work is devoted to Porasil C silica, with organic compounds bonded to its surface and capable of electron-donor-acceptor (EDA) interactions. These packings are a good base for studying interactions among stationary phases and the adsorbate molecules showing electron-donor properties. The presented work concentrates on the phases containing ketoimino groups at their surface. Copper and chromium chlorides were bonded through these to the surface. Physicochemical characteristics of the obtained packings were determined by the use of elemental analysis, differential scanning calorimetry (DSC) and inverse gas chromatography. We examined the influence of the surface modification on the retention parameters of the nucleophilic compounds.

Chromatography, Gas↗

PubMed2001

Effect of solid surface composition on the migration of tributyltin in groundwater.

Tributyltin (TBT) is the most important organotin compound that has been introduced into aquatic ecosystems. A better understanding of its interactions with solid surfaces is essential to estimate the possibilities of TBT migration through subsurface environments. For this purpose, TBT sorption onto a porous matrix of natural origin, a quartz sand as an aquifer material, was studied at low concentration levels with a monodirectional model of column type allowing sequential investigation of sorption and desorption processes. Different treatments of the solid phase were performed by injecting alkaline solutions, NaOH at pH 10.8 or NaClO-NaCl at pH 11.5, by decreasing the ionic strength or by adding kaolinite to change the surface composition and properties. The removal of iron and aluminum (hydr)oxides from the sand surface did not affect so much the sorption (decrease in 14% as compared to sorption on the raw sand). The original use of X-ray photoelectron spectroscopy to control treatment efficiency and to characterize sand surface modifications permitted to relate TBT sorption onto the aquifer material to quartz, the main component of the sand, and clay minerals (mainly kaolinite) present at trace levels at the sand surface. A first attempt of transport modeling with these two surface sites showed the consistency of our assumption. Moreover, estimation of Langmuir-type constants showed that TBT sorption affinity for the quartz surface (KL = 26.7 L micromol(-1)) was much greater than for kaolinite (KL = 6.3 L micromol(-1)).

Adsorption↗

PubMed2001

Functionalization of silicone rubber for the covalent immobilization of fibronectin.

Surface modification techniques were employed in order to provide functionalized silicone rubber with enhanced cytocompatibility. Acrylic acid (AAc), methacrylic acid (MAAc) and glycidylmethacrylate (GMA) were graft-co-polymerized onto the surface of silicone induced by an argon plasma and thermal initiation. The polymerizations were carried out in solution, in the case of acrylic acid a vapor phase graft-co-polymerization subsequent to argon plasma activation was carried out as well. Human fibronectin (hFn), which acts as a cell adhesion mediator for fibroblasts, was immobilized by making use of the generated carboxylic or epoxy groups, respectively. Surface analysis was accomplished by means of X-ray photoelectron spectroscopy (XPS), infrared spectroscopy in attenuated total reflection mode (IR-ATR), scanning electron microscopy (SEM), atomic force microscopy (AFM) and dynamic contact angle measurements using the Wilhelmy-plate method. The amount of immobilized active hFn was semiquantified by enzyme-linked immunosorbent assay (ELISA) using a structure-specific antibody against the cell-binding domain of hFn. In vitro testing showed a remarkable difference between surfaces exposing adsorbed-only and surfaces with covalently immobilized hFn.

Journal Article↗

PubMed2005

Effects of glow-discharge and surfactant treatments on the wettability of vinyl polysiloxane impression materials.

STATEMENT OF PROBLEM: Although surfactant-modified vinyl polysiloxane (VPS) is described as hydrophilic by manufacturers, interaction with dental gypsum is relatively poor. PURPOSE: The purpose of this study was to compare and evaluate the wettability of surfactant-modified VPS after different surface treatments. MATERIAL AND METHODS: Eighty-four impression-material specimens (20 x 10 x 1 mm) were prepared from 3 different brands of VPS (Aquasil, Panasil Contact Plus, and Accuflex). Four groups (n = 7) of specimens were established according to the surface treatment method used: no treatment, topical application of 2 different surface wettability agents (Silwet Copolymer L-77 or Delar surfactant), or coating with an acrylic acid plasma in a glow-discharge reactor. Plasma treatment specimens were coated with acrylic acid in a glow-discharge system at a radio frequency of 13.56 MHz with 20-W discharge power and 5 minutes of exposure time. Wettability was measured using the contact-angle method. Values were recorded after the drop contacted the surface at 0.6 second, 30.7 seconds, and 210.8 seconds. Contact-angle mean values were compared using 3-way analysis of variance with repeated measures on 1 factor, followed by a post hoc Duncan test (alpha=.05). RESULTS: As the sphericity assumption was not satisfied, the Greenhouse-Geisser correction was used for contact-angle values. Glow-discharge treatment proved to be effective for increasing the surface energy of the VPS compared to controls at all time points studied (P <.0001). At 0.6 second, Silwet significantly decreased the contact-angle values for Aquasil and for Panasil Contact Plus (P <.0001). Delar treatment, at this time point, significantly increased the contact-angle values of GC (P <.0001) and decreased the contact-angle values of Aquasil (P <.0001). At 30.7 seconds, Silwet significantly increased the wettability of Aquasil and Panasil Contact Plus ( P <.0001) but did not significantly increase the wettability of GC. Delar treatment, at 30.7 seconds, increased the contact-angle values of GC (P <.0001), whereas contact-angle values of Aquasil significantly decreased (P <.0001). At 210.8 seconds, all surface-modification methods used were effective in increasing the wettability of VPS tested over untreated controls (P <.0001). CONCLUSION: Wettability of VPS-based impression materials can be increased by coating the surface with acrylic acid in a glow-discharge reactor. The change in wettability achieved by the application of topical surfactants resulted in variations among surfactant-VPS combinations.

Acrylates↗

PubMed2003

Ion implantation: surface treatment for improving the bone integration of titanium and Ti6Al4V dental implants.

Dental implants subjected to surface treatment have shown better bone integration than implants which have only been turned (machined). Three main types of treatment are presently available: the addition of material or coating, the removal of material, and surface modification. Ion implantation corresponds to the third approach. A histomorphometric study is made following the rabbit tibial bone placement of 88 commercial dental implants of pure titanium and Ti6AI4V subjected to surface treatment in the form of different ion implants (C+, CO+, N+, Ne+). Light microscopic, scanning electron microscopic (SEM), electron microsonde (EDS) and X-ray photoelectron spectroscopy (XPS) studies were made. The results indicate improved bone integration (expressed as percentage bone-implant contact) in those specimens subjected to ion implantation versus the non-treated controls, the difference being statistically significant for the groups treated with C+ and CO+. In these groups, XPS showed a Ti-O-C junction (bone-implant interface) involving covalent type bonds, these being stronger and more stable than the ion-type bonds usually established between the titanium oxide and bone.

Alloys↗

PubMed1971

Studies on gonococcus infection. I. Pili and zones of adhesion: their relation to gonococcal growth patterns.

The four colony types of several different strains of gonococci were isolated by selective transfers on agar. These colony variants differed in the degree of autoagglutination which occurred when they were grown in fluid medium. It was found that this clumping behavior was related to the colonial type, with type 2 isolates exhibiting the greatest autoagglutination followed by types 3, 1, and 4. Electron microscopic examination of thin sections indicated that the clumping in fluid medium was mediated by peculiar zones of adherence of the outer membranes of gonococci. These resembled the gap junctions seen in animal cell systems but differed in that the gonococcal membranes involved in the zone of adherence did not bear typical surface modifications. Electron microscopic study of negatively stained specimens of gonococci revealed that pili with a diameter of approximately 85 A and a length up to 4 micro were present on the surfaces of all type 1 and type 2 gonococci examined, and were not seen on any type 3 or 4 gonococci. The consistent presence of pili on type 1 and type 2 gonococci which are virulent colony forms and the lack of pili on avirulent colony types 3 and 4 suggests a relationship between the gonococcal pili and pathogenetic potential of the organisms.

Agar↗

PubMed2026

Single antiplatelet therapy and tirofiban bridged with surface modified flow diverters for ruptured blood blister-like aneurysms: single center experience and systematic review.

BACKGROUND: Blood blister-like aneurysms (BBAs) of the internal carotid artery are rare but high risk lesions that frequently re-rupture due to their fragile structure and dissecting pathology. Treatment is particularly challenging in ruptured cases, given the risks associated with dual antiplatelet therapy. Recent advancements in flow diverter stents (FDSs) with surface modifications, and the use of single antiplatelet therapy (SAPT), offer a potential alternative strategy. METHODS: We conducted a retrospective review of 17 patients with ruptured internal carotid artery BBAs treated with surface modified FDS under SAPT (ticagrelor or prasugrel) bridged periprocedurally with intravenous tirofiban. All procedures were performed within the acute phase of subarachnoid hemorrhage. Clinical, radiographic outcomes, and procedure related complications were evaluated. RESULTS: Among 17 patients, 94.1% achieved complete angiographic occlusion, and 76.5% attained favorable clinical outcomes (modified Rankin Scale score ≤2). No aneurysm rebleeding or device related ischemic events occurred. A total of 11 patients underwent external ventricular drainage or ventriculoperitoneal shunting without discontinuing SAPT, and no hemorrhagic complications were observed. A literature review incorporating seven additional series identified a total of 42 FDS plus SAPT treated BBA cases, with similar safety and efficacy profiles. CONCLUSIONS: Surface modified FDS with SAPT and tirofiban bridging appears to be a promising treatment option for ruptured BBAs, offering high occlusion rates with minimal thromboembolic and hemorrhagic complications. Larger prospective studies are needed to validate these findings.

Humans↗

PubMed2006

A new chemical etching process to improve endosseous implant osseointegration: in vitro evaluation on human osteoblast-like cells.

The development of novel mechanical and chemical surface modification treatments to improve the osteointegration properties of osseointegrated dental implants is nowadays a topic of great applicative interest. The aim of the present study was to analyse the role of surface topography and chemistry of four different surface treatments on titanium by an in vitro human osteosarcoma immortalised cell line model (MG63). The surface treatments considered were (a) machined titanium, (b) chemical etched on machined titanium, (c) sandblasted titanium and (d) chemical etching on sandblasted titanium. Chemical and physical surface properties were investigated by Scanning Electron Microscopy, Thin Film-X ray Diffraction and by Laser Profilometry. The in vitro biological response was characterised using the MG63 cell line by elution cytotoxicity tests, cell morphology, adhesion, proliferation activity, alkaline phosphatase activity and total DNA content in order to show a relationship between osteoblast response and surface features. Chemical and physical characterisation showed that the considered treatments differently modify the surface morphology in the micro and sub-micrometric scale. Although some differences in alkaline phosphatase activity were observed in the biological characterisation, depending on the specific material's surface finishing, the results showed that cells were well responsive on all the tested materials and grew and differentiated with similar proliferation rate.

Air Abrasion, Dental↗

PubMed1979

Surface morphology of macrophages in the regressing corpus luteum, as revealed by scanning electron microscopy.

Activated macrophages phagocytize moribund luteal cells and thus play a central role in the postpartum regression of corpora lutea in guinea pigs (Paavola, '79). When viewed by transmission electron microscopy (TEM), these luteal macrophages exhibit many surface protrusions. To characterize more fully the nature and extent of these evaginations, as well as to gain further understanding of phagocytes in their natural surroundings, luteal macrophages were studied in situ by scanning electron microscopy of regressing corpora lutea. Correlated TEM was carried out to confirm the identity of the various cell types. Even in low power scanning electron micrographs, macrophages are consipicuous, and can be readily distinguished from luteal cells by their surface topography. Luteal cell surfaces bear low ridge-like folds and sparse microvilli. In contrast, macrophages characteristically exhibit highly developed surface projections, the most common of which are knob-like or clubbed processes of varying size and shape. Other distinctive surface modifications displayed by luteal macrophages include long, slender filopodia, and well developed pseudopodia. These processes generally have an uneven distribution over the cell; thus, luteal macrophages may appear polarized with regard to surface activity. Both filopodia and pseudopodia occur in close contact with luteal cell surfaces. In addition, occasional luteal macrophages have surfaces that are covered with large, crater-like depressions. The phagocytosis of cells and cellular debris by macrophages was also observed. In summary, the highly pleomorphic surface activity of luteal macrophages appears to be correlated with their role in the removal of senescent luteal cells.

Animals↗

PubMed1993

Tissue reactions to subcutaneously implanted, surface-modified silicones.

To evaluate the influence of surface properties on tissue reactions, the surface of a medical-grade silicone elastomer was modified without changing the bulk properties. Surface modifications employed were oxidation by corona discharge in air, graft polymerization of water-soluble monomers, coating a polysaccharide through polyion complex formation, and covalent immobilization of cell-adhesive proteins. Surface-modified silicone sheets were implanted in the subcutaneous tissue of rats, and tissue reactions such as infiltration of inflammatory cells, appearance of foreign-body giant cells, and collagenous capsule formation were studied. It was found that the thickness of collagenous capsules formed after 16 weeks' implantation was in the range of 85-95 microns for the nontreated ones and all the modified silicones except the acrylic acid-grafted and the collagen-immobilized silicones.

Animals↗

PubMed2003

Differentiation of human bone-derived cells grown on GRGDSP-peptide bound titanium surfaces.

Various surface modifications have been applied to titanium alloy (Ti-6Al-4V) implants, in an attempt to enhance osseointegration; crucial for ideal prosthetic fixation. Despite the numerous studies demonstrating that peptide-modified surfaces influence in vitro cellular behavior, there is relatively little data reporting their effects on bone remodeling. The objective of this article was to examine the effects of chemically modifying Ti-6Al-4V surfaces with a common RGD sequence, a 15-residue peptide containing GRGDSP (glycine-arginine-glycine-aspartate-serine-proline), on the modulation of bone remodeling. The expression of proteins known to be associated with osseous matrix and bone resorption were studied during the growth of human bone-derived cells (HBDC) on these peptide-modified surfaces. HBDC grown for 7 days on RGD surfaces displayed significantly increased levels of osteocalcin, and pro-collagen Ialpha1 mRNAs, compared with the production by HBDC grown on the native Ti-6Al-4V. A pattern that was also reflected at the protein levels for osteocalcin, type I collagen, and bone sialoprotein. Moreover, HBDC grown for 7 and 14 days on RGD-modified Ti-6Al-4V expressed significantly higher level of osteoclast differentiation factors and lower levels of osteoprotegerin and IL-6 proteins compared with other surfaces tested. These results suggest that different chemical treatments of implant material (Ti-6Al-4V) surface result in differential bone responses, not only their ability to form bone but also to stimulate osteoclastic formation.

Amino Acid Sequence↗

PubMed2006

Mesenchymal stem cell adhesion and spreading on microwave plasma-nitrided titanium alloy.

Improved methods to increase surface hardness of metallic biomedical implants are being developed in an effort to minimize the formation of wear debris particles that cause local pain and inflammation. However, for many implant surface treatments, there is a risk of film delamination due to the mismatch of mechanical properties between the hard surface and the softer underlying metal. In this article, we describe the surface modification of titanium alloy (Ti-6Al-4V), using microwave plasma chemical vapor deposition to induce titanium nitride formation by nitrogen diffusion. The result is a gradual transition from a titanium nitride surface to the bulk titanium alloy, without a sharp interface that could otherwise lead to delamination. We demonstrate that vitronectin adsorption, as well as the adhesion and spreading of human mesenchymal stem cells to plasma-nitrided titanium is equivalent to that of Ti-6Al-4V, while hardness is improved 3- to 4-fold. These in vitro results suggest that the plasma nitriding technique has the potential to reduce wear, and the resulting debris particle release, of biomedical implants without compromising osseointegration; thus, minimizing the possibility of implant loosening over time.

Cell Adhesion↗

PubMed1995

Development and characterization of a wettable surface modified aromatic polyethersulphone using glow discharge induced HEMA-graft polymerisation.

The aromatic polyethersulphone (PES) is a well known polymer for the preparation of membranes with excellent thermal stability and chemical resistance. The disadvantage of PES-membranes is their hydrophobic character, which in contact with protein containing solutions leads to high protein adsorption and as a consequence to deterioration of membrane properties. In this report the surface modification of PES by means of glow discharge induced grafting of 2-hydroxyethyl methacrylate (HEMA) is described. Graft polymerisation creates a largely wettable layer of poly(2-hydroxyethyl methacrylate) (PHEMA) on the surface of PES. This has been shown by contact angle measurements using the Wilhelmy plate method. Chemical characterization is carried out by means of X-ray photoelectron spectroscopy (XPS) and infrared spectroscopy/attentuated total reflection (FTIR-ATR). The influence of storage conditions on the surface properties of modified PES samples has been investigated after storage in vacuum, water, and air.

Journal Article↗