SEARCH · PubMed Health

Results for “Wettability”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 19 recordsLinked to original sources

PubMed1998

Platelet adhesion onto wettability gradient surfaces in the absence and presence of plasma proteins.

A wettability gradient was prepared on lowdensity polyethylene (PE) sheets by treating them in air with a corona from a knife-type electrode the power of which increased gradually along the sample length. The PE surfaces oxidized gradually with the increasing corona power and a wettability gradient was created on the surfaces, as evidenced by the measurement of water contact angles, Fourier transform infrared spectroscopy in the attenuated total reflectance mode, and electron spectroscopy for chemical analysis. The wettability gradient surfaces prepared were used to investigate the adhesion behavior of platelets in the absence and presence of plasma proteins in terms of the surface hydrophilicity/hydrophobicity of polymeric materials. The platelets adhered to the wettability gradient surfaces along the sample length were counted and examined by scanning electron microscopy (SEM). It was observed that the platelet adhesion in the absence of plasma proteins increased gradually as the surface wettability increased along the sample length. The platelets adhered to the hydrophilic positions of the gradient surface also were more activated (possessed more pseudo pods as examined by SEM) than on the more hydrophobic ones. However, platelet adhesion in the presence of plasma proteins decreased gradually with the increasing surface wettability; the platelets adhered to the surface also were more activated on the hydrophobic positions of the gradient surface. This result is closely related to plasma protein adsorption on the surface. Plasma protein adsorption on the wettability gradient surface increased with the increasing surface wettability. More plasma protein adsorption on the hydrophilic positions of the gradient surface caused less platelet adhesion, probably due to platelet adhesion inhibiting proteins, such as high-molecular-weight kininogen, which preferably adsorbs onto the surface by the so-called Vroman effect. It seems that both the presence of plasma proteins and surface wettability play important roles for platelet adhesion and activation.

Animals↗

PubMed1996

Wettability of Oil-Producing Reservoir Rocks as Determined from X-ray Photoelectron Spectroscopy

Wettability has a dominant effect in oil recovery by waterflooding and in many other processes of industrial and environmental interest. Recently, the suggestion has been made that surface science analytical techniques (SSAT) could be used to rapidly determine the wettability of reservoir materials. Here, we bring the capability of X-ray photoelectron spectroscopy (XPS) to bear on the wettability evaluation of producing reservoir rocks. For a suite of freshly exposed fracture surfaces of rocks we investigate the relationship between wettability and surface composition as determined from XPS. The classical wettability index as measured with the Amott-Harvey test is used here as an indicator of the wettability of natural sandstones. The XPS spectra of oil-wet surfaces of rocks reveal the existence of organic carbon and also of an "organic" silicon species, of the kind Si-CH relevant to silanes, having a well-defined binding energy which differs from that of the Si-O species of mineral grains. We provide quantifiable evidence that chemisorbed organic material on the pore surfaces defines the oil-wetting character of various reservoir sandstones studied here which on a mineralogic basis are expected to be water-wet. This view is supported by a strong correlation between C content of pore surfaces and rock wettability. The results also suggest a correlation between organic silicon content on the pore surfaces and rock hydrophobicity.

Journal Article↗

PubMed1990

Effect of disinfectant solutions on the wettability of elastomeric impression materials.

The wettability of impression material affects the number or volume of air bubbles generated during the pouring of gypsum casts. This study was done to determine the effect of various commercial disinfectant solutions on the wettability of elastomeric impression materials. The technique of measuring advancing contact angles of aqueous solutions of calcium sulfate was used to determine changes in the wettability of four types of impression material before and after immersion in one of five disinfectants. All disinfectant solutions that were tested increased the wettability of polysulfide. Chlorine dioxide produced the greatest increase in the wettability of polysulfide by decreasing the contact angle on polysulfide at least 48 degrees. All disinfectants decreased the wettability of hydrophilic addition silicone by increasing the contact angle up to approximately 30 degrees. The differences were significant as determined by paired Student t-tests. Addition silicone was the material most resistant to change in contact angle. Chlorine dioxide had the greatest beneficial effect on wettability.

Analysis of Variance↗

PubMed1992

Influence of substratum wettability on the strength of adhesion of human fibroblasts.

To determine the strength of adhesion and the detachment mechanisms of fibroblasts from substrata with different wettability, the behaviour of adhered cells was studied in a parallel-plate flow chamber during exposure to shear. Adhered cells were observed in situ, i.e. in the flow chamber, by phase-contrast microscope and images were analysed semiautomatically. Detachment was found to be dependent both on shear stress and time, although a critical shear stress can be found below which no detachment occurs. On all substrata, cells round up before detachment and are approximately spherical immediately before detachment. The strength of adhesion calculated ranged from 0.6-3.5 x 10(-10) N per cell on FEP-Teflon (the least wettable material included) to 9.4 x 10(-9) N per cell for glass (the most wettable). Ease of detachment seemed to decrease with increasing wettability. However, cells reacted more strongly with tissue culture polystyrene (TCPS) than expected on the basis of its wettability, probably due to surface chemistry.

Cell Adhesion↗

PubMed1997

Effects of radiofrequency glow discharge on impression material surface wettability.

STATEMENT OF PROBLEM: Argon radiofrequency glow discharge (RGD) may simultaneously sterilize and improve surface wettability of impression materials. PURPOSE: The purpose of this study was to define RGD technical parameters that influence the surface wettability of impression material (optimization phase). Definition of RGD was followed by an assessment of these optimized RGD parameters on the wettability of four impression materials either uncontaminated or contaminated with saliva, compared with conventional liquid disinfection (application phase). MATERIAL AND METHODS: For the optimization phase, addition silicone samples were cast against glass with 10 samples per group/parameter (n = 210). Parameters evaluated were duration of exposure, sample shape and angle, position within the RGD chamber, and argon gas delivery pressure. Changes in surface wettability were determined with contact angle measurements. For the application phase, standardized RGD parameters (90 degrees to the plasma flow, flat, 60 seconds, 5 psi) were used on four groups of impression materials with (n = 120 samples, 30 per material) or without (n = 120 samples, 30 per material) prior saliva contamination. RESULTS: RGD treatment of a polyvinyl siloxane impression material significantly (p < 0.0001) reduced contact angle measurements from 63 +/- 1 to 13 +/- 4 degrees, regardless of the parameter evaluated. For the application phase, results indicated different responses to RGD relative to nontreated controls. With all materials treated with RGD or disinfectant exposure, the finest 20 microns standard line was reproduced at x10 magnification with the American National Standards Institute/American Dental Association Specification 19 test die (Sabri Enterprise, Downers Grove, Ill.; n = 80, 10 samples per group). CONCLUSION: These results suggest RGD selectively alters impression material surface wettability.

Analysis of Variance↗

PubMed1999

Time-related wettability characteristic of acrylic resin surfaces treated by glow discharge.

STATEMENT OF PROBLEM: Adhesion and cohesion have important roles in denture retention, and attempts have been made to improve the wettability of the acrylic resin material by surface treatments. PURPOSE: This study examined the initial and subsequent wettability of an acrylic resin denture base material treated under air or argon plasma atmosphere before and after exposure to air or distilled water. MATERIAL AND METHODS: Acrylic resin specimens were treated with plasma under air or argon atmosphere and were either exposed to air or distilled water for up to 60 days. Wettability characteristics of the acrylic resin specimens were determined by contact-angle measurements after 2 hours and after 60 days. Surface composition of the specimens also was analyzed with x-ray photoelectron spectroscopic (XPS) measurements. RESULTS: Statistically significant difference was found between control and each of the plasma treatment groups (P <.05). Although the storage condition and storage period caused statistically significant difference on contact angle values (P <.05), atmosphere type did not have any effect on the results (P >.05). XPS spectra of the plasma-treated specimens differed from control specimens only in the O1s region with a narrower and more intense peak that could be assigned to -COH groups. During 60 days of exposure, the O/C atomic ratios decreased within the first 2 weeks but settled to 0.40 and 0. 32 up to 60 days compared with 0.26 for untreated control specimens. CONCLUSION: Glow discharge plasma altered the surfaces of the acrylic resin and increased thc wettability as shown both by XPS and contact-angle measurements, and plasma treatment seemed to offer a durable (at least up to 60 days) wettability.

Acrylic Resins↗

PubMed1999

Effect of acid etching and collagen removal on dentin wettability and roughness.

It was recently reported that removal of the collagen network from etched dentin does not affect dentin bond strengths. The aim of this study was to determine if the removal of the collagen fibers results in changes in dentin roughness and wettability. Twenty cary-free extracted human third molars were sectioned parallel to the occlusal surface to expose either superficial or deep dentin. Dentin was ground flat through 600-grit SiC abrasive paper under water to provide uniform surfaces. Observed contact angle measurements were performed to assess wettability by using the axisymmetric drop shape analysis technique using water and a water-based primer. Average roughness was determined with a profilometer. The specimens were analyzed just after being ground, after etching with 35% H(3)PO(4) gel for 15 s, and after etching and deproteinization with 5% NaOCl for 2 min. Data were analyzed with two-way ANOVA and Newman-Keuls multiple comparison t test procedure. Etching resulted in an increase in surface roughness and dentin wettability. For deep dentin, collagen removal did not influence the average roughness, but it resulted in a significantly greater degree of wettability. The degree of wettability for deep dentin was greater than for superficial dentin.

Acid Etching, Dental↗

PubMed1998

Interaction of Different Types of Cells on Polymer Surfaces with Wettability Gradient.

Gradient surfaces whose properties are changed gradually along the sample length are of particular interest for basic studies of the interaction between biological species and surfaces since the effect of a selected property can be examined in a single experiment on one surface. We prepared a wettability gradient on low density polyethylene (PE) sheets by treating them in air with the corona from a knife-type electrode whose power increases gradually along the sample length. The PE surfaces oxidized gradually with the increasing corona power, and the wettability gradient was created on the surfaces as evidenced by the measurement of water contact angles, Fourier transform infrared spectroscopy in the attenuated total reflectance mode, and electron spectroscopy for chemical analysis. The wettability gradient surfaces prepared were used to investigate the interaction of different types of cells (Chinese hamster ovary, fibroblast, and endothelial cells) as well as serum proteins in terms of the surface hydrophilicity/hydrophobicity of polymeric materials. The cells adhered and grown on the gradient surface along the sample length were counted and observed by scanning electron microscopy. It was observed that the cells were adhered, spread, and grown more onto the positions with moderate hydrophilicity of the wettability gradient surface than onto the more hydrophobic or hydrophilic positions. The maximum adhesion and growth of the cells appeared at around water contact angles of 55 degrees, regardless of the cell types used. This result seems closely related to the serum protein adsorption on the surfaces; the serum proteins were also adsorbed more onto the positions with moderate hydrophilicity of the wettability gradient surface. Copyright 1998 Academic Press.

Journal Article↗

PubMed1990

An evaluation of the surface characteristics of a facial prosthetic elastomer. Part III: Wettability and hardness.

Silicone facial prosthetic elastomers may cause tissue damage by abrasion. Such damage is a particular concern when prostheses are mechanically retained against tissues compromised by adjunctive therapy. The hardness and wettability of Cosmesil material was compared with that of Molloplast-B material. The stone test surfaces were separated with soap, sodium alginate, silicone paste, and left untreated. A polished stainless steel surface was prepared as a control. The specimens of Cosmesil and Molloplast-B materials were processed against each of these surfaces. Ten specimens of each material were processed against the five different surfaces. Wettability was evaluated by measuring the contact angle with a profile projector. Indentation hardness was measured with a Shore-A durometer. Statistical analysis involved multiple analyses of variation and Tukey's procedures (in all cases p less than 0.05). Molloplast-B material was found to have a higher wettability than Cosmesil material (means = 3.22 degrees higher); sodium alginate separator yielded silicone specimens with the highest wettability; Molloplast-B material was found to be harder than Cosmesil material (means = 9.75 Shore-A indentation units harder). The softest silicones were processed with soap separator. Silicone grease yielded the hardest specimens. The mechanical performance of Cosmesil material would be enhanced by increasing the surface wettability. The hardness of Cosmesil material is within the ideal range for a maxillofacial prosthetic elastomer.

Biocompatible Materials↗

PubMed1999

Interaction of fibroblast cells on poly(lactide-co-glycolide) surface with wettability chemogradient.

Chemogradient surfaces whose properties are changed gradually along the sample length are of particular interest for the basic studies of the interaction between biological species and surfaces since the effect of a selected property can be examined in a single experiment on one surface. A wettability chemogradient on the poly(L-lactide-co-glycolide) (PLGA) films by treating them in air with corona from a knife-type electrode whose power increases gradually along the sample length. The PLGA surfaces oxidized gradually with the increasing corona power, and the wettability chemogradient was created on the surfaces as evidenced by the measurement of water contact angles and electron spectroscopy for chemical analysis. The wettability chemogradient PLGA surfaces prepared were used to investigate the interaction of fibroblast cells in terms of the surface hydrophilicity/hydrophobicity of PLGA surface. The cells adhered and grown on the chemogradient surface along the sample length were counted and observed by scanning electron microscopy. It was observed that the cells were adhered, spread, and grown more onto positions with moderate hydrophilicity of the wettability chemogradient PLGA surface than onto the more hydrophobic or hydrophilic positions. The maximum adhesion and growth of the fibroblast cells appeared at around water contact angle of 55 degrees. It seems that the wettability plays important roles for cell adhesion, orientation, spreading and growth on the PLGA surface. It might be that this surface modification technique can be used for improving the adhesion and growth of cell onto PLGA film and scaffolds, and can be applicable in the area of the tissue engineering.

3T3 Cells↗

PubMed1989

Effects of "wettability" of biomaterials on culture cells.

New objectives of the development of biomaterials in recent years include how to control surface characteristics of materials and the attachment of cells to implant sites. This study clarified the effect of "wettability" of materials on culture cells, with wettability being expressed by the contact angle of the material to the water. First, low-temperature plasma treatment was administered so that samples of the same materials and shapes could be obtained, differing only in wettability. The contact angles at the surfaces of the samples and their surface roughness were then measured, and surfaces were analyzed by ESCA. For clarification of the biological response of the cell to wettability, attachment of connective tissues and epithelial-tissue-originated established cell lines to the material and its cell spreading were investigated in each test sample. As a result, it was found that the contact angle of each material used in the experiment affected both the cell attachment and spreading rates; thus, wettability of biomaterials is considered to be an important parameter of biological effect at the cell level.

Animals↗

PubMed1999

Wettability of silicone rubber maxillofacial prosthetic materials.

STATEMENT OF PROBLEM: Maxillofacial prosthetic materials that contact skin or mucosa should have good wettability. A material that is easily wetted will form a superior lubricating layer between the supporting tissues and, thus, reduce friction and patient discomfort. The surface energy of a maxillofacial prosthetic material will give an indication of the amount of energy available for adhesion and of the susceptibility of the material to bacterial adhesion. PURPOSE: This study evaluated the wettability and surface energies of a range of commercially available silicone rubber maxillofacial prosthetic materials. MATERIAL AND METHODS: Contact angles and surface energies were measured by using a dynamic contact angle measuring technique. Four commonly used silicone maxillofacial materials were tested and their properties compared with those of an acrylic resin denture base material and a widely used denture soft lining material. RESULTS: There were no significant differences in the wettability of the silicone rubber materials. All materials were significantly less wetted than the denture acrylic resin material. There were no significant differences in the surface energies of the silicone rubber materials, but all were significantly lower than denture acrylic resin material. CONCLUSIONS: The Cahn dynamic contact angle analyzer was a quick and reproducible method for determining the contact angles and surface energies of maxillofacial materials. Further work is needed to improve the wettability of silicone rubber materials used for maxillofacial prostheses, thus, reducing their potential to produce friction with tissues.

Acrylic Resins↗

PubMed1996

Studies on the biocompatibility of materials: fibroblast reorganization of substratum-bound fibronectin on surfaces varying in wettability.

The ability of human fibroblasts to remove and reorganize fibronectin (FN) bound on material surfaces was studied as a novel feature of material surface biocompatibility. Other traditional parameters of biocompatibility analyzed included cell spreading, clustering of fibronectin receptors into focal adhesions, development of stress fibers, and cell growth. Five different materials with surface wettability ranging from hydrophilic (underwater contact angle 25 degrees) to hydrophobic (underwater contact angle 111 degrees) were used, i.e., clean glass (GLASS), aminopropylsilane (APS), octadecylsilane (ODS), polylactate (PL), and silicone (SI). When cells were cultured on these materials in serum-containing medium, formation of FN receptor-rich focal adhesions and actin stress fibers were more evident on the hydrophilic surfaces (GLASS and APS) compared to the hydrophobic ones (PL, ODS, and SI). Cell growth showed a similar pattern, that is, increased cell proliferation with increasing material surface wettability. Preadsorption of FN on the material surfaces increased subsequent cell spreading and cytoskeletal reorganization on hydrophobic surfaces except SI. Removal and reorganization of FN from the material surfaces into extracellular matrixlike structures occurred on GLASS but not on less wettable surfaces, suggesting that this removal/reorganization process may be more sensitive to changes in surface wettability than other parameters of biocompatibility.

Actins↗

PubMed1996

Fibronectin matrix formation by human fibroblasts on surfaces varying in wettability.

The spatial organization of extracellular fibronectin on biomaterial surfaces might be important for interaction with tissue cells. In previous investigations we have demonstrated that hydrophilic materials bind preadsorbed fibronectin that can easily be reorganized by fibroblasts in a specific matrix-like structure, while on less wettable materials (possessing water contact angles above 60 deg) the cells were unable to do this. As the cells continuously produce their fibronectin matrix, we tried in this study to answer the question of how the surface wettability of biomaterials influences the endogenous fibronectin matrix formation and its subsequent organization on the substrate. We cultured fibroblasts for 72 h on five different wettable surfaces: glass, aminopropyltriethoxysilane, pellethane, polyvinylchloride, and silicone, with water-contact angles gradually ranging from 25 to 105 deg. We demonstrated that the decreasing wettability of the materials significantly reduced endogenous fibronectin deposition on the substratum. Moreover, fibrillar organization of fibronectin appeared only on relatively hydrophilic glass and APS substrate, while on more hydrophobic materials like PVC and SI, cells secreted some fibronectin but were not able to organize it into a fibronectin matrix. These results were correlated with an altered cell morphology and spreading on these materials. In addition, an ELISA method has been implemented to quantify fibronectin matrix formation as a possible measure of the biocompatibility of materials, where a clear relation has been found between fibroblast growth and fibronectin matrix formation.

Adsorption↗

PubMed1996

Polymeric membranes for hybrid liver support devices: the effect of membrane surface wettability on hepatocyte viability and functions.

Extracorporeal therapies based on membrane hybrid liver support devices using primary hepatocytes are an interesting approach to the treatment of acute hepatic failure. In such devices, semipermeable polymeric membranes are effectively used as immunoselective barriers between a patient's blood and the xenocytes in order to prevent the immune rejection of the graft. The membranes may act also as the substratum for cell adhesion, thus favouring the viability and functions of anchorage-dependent cells such as the hepatocytes. Membrane cytocompatibility is expected to depend on the surface properties of the polymer, such as its morphology and its physico-chemical properties. In this paper, we report our investigation on the effect of the surface wettability of membranes on hepatocyte viability and functions. Polypropylene microporous membranes were modified to increase their surface wettability and were used as substrata for rat hepatocyte adhesion culture. Isolated hepatocytes were also cultured on collagen as a reference substratum. Hepatocyte viability generally improved as the cells were cultured on more wettable membranes. In agreement with the viability data, the increasing wettability of the membrane surface also improved some metabolic functions.

Animals↗

PubMedDate not supplied

Hydrophilic poly(vinyl siloxane) impression materials: dimensional accuracy, wettability, and effect on gypsum hardness.

Three hydrophilic poly(vinyl siloxane) impression materials, containing an intrinsic surfactant, were compared with a hydrophobic poly(vinyl siloxane) and a polyether impression material. The hydrophobic poly(vinyl siloxane) material was dimensionally more accurate than the hydrophilic poly(vinyl siloxane) in two of three measured dimensions, but the difference was small. The polyether material was the most wettable, and the hydrophilic poly(vinyl siloxane) were more wettable than the hydrophobic poly(vinyl siloxane). However, when a topical surfactant was used, no difference in wettability was noted between the hydrophilic and hydrophobic poly(vinyl siloxane), and their wettability was comparable to the polyether material, indicating that the topical surfactant was more effective than the intrinsic surfactants. Stone dies made from the hydrophobic poly(vinyl siloxane) material were harder than those obtained from the other materials.

Analysis of Variance↗

PubMed1999

Improved wettability of an experimental silicone rubber denture soft lining material.

The purpose of this study was to improve the wettability of an experimental silicone rubber soft lining material (Sildent) to increase patient comfort. Sildent was modified by the addition of polyalkylene oxide poly(dimethylsiloxane) surfactants. The various surfactants were added directly to the polymeric matrix in the quantities 5, 10, 20% w/w. The surfactants were also added to a one part silicone sealant, which was then painted onto the surface of already cured Sildent. Contact angle measurements were made on samples using a dynamic contact angle analyzer. Results showed that incorporation of surfactants A (Silwet L7600) and B (Silwet L7607) effectively improved the wettability of Sildent. This improvement was still evident after 6 months storage in distilled water at 37 degrees C suggesting retention of the surfactants matrix via physio-chemical bonding. Formulations with surfactants added directly to the matrix showed unacceptable water absorption after 2 months in distilled water. Samples with surfactant charged sealant painted on the surface showed a lower water absorption. In conclusion, Sildent formulations modified with polyalkylene silicone surfactants showed improved wettability compared to unmodified Sildent. Further work is needed to reduce water uptake and determine the effect on key mechanical properties.

Catalysis↗

PubMed1994

Adhesion of human peripheral blood lymphocytes is dependent on surface wettability and protein preadsorption.

The influence of surface wettability and preadsorption of plasma proteins on cell adhesion was studied using human peripheral blood lymphocytes (PBL). Hydrophilic glass and hydrophobic octadecyl glass were used as model surfaces with known wettability. The adhesion of PBL was investigated under non-flow conditions that are considered as a model for the adhesion of migrating lymphocytes in the tissue. Furthermore, adhering lymphocytes were exposed to increasing shear forces to investigate the detachment under laminar flow conditions to simulate the situation during blood flow. The proteins used in this study were attachment proteins such as fibrinogen, fibronectin and vitronectin. Human serum albumin was used as a control. It was found under both conditions (static and dynamic) that PBL adhesion was strongly influenced by the wettability of the surfaces. Furthermore, it was shown that the properties of the underlying surface influenced the interaction between preadsorbed attachment proteins and PBL.

Blood Proteins↗