PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “surface modification”

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 307 records · Page 17Linked to original sources
PubMed1978

Cell surface modifications in neuronal maturation.

Changes in carbohydrate composition of the cell surface related to neuronal maturation have been studied on neuroblastoma and embryonic dorsal root ganglia (DRG) cultures by using fluorescein conjugated lectins. In neuroblastoma cells, it has been found that the surface of the fibers differs from that of the cell body as shown by concanavalin A (Con A) and WGA binding. In primary cultures of embryonic DRG, lectin binding has also shown that the neuron surface undergoes changes during maturation. In fact, lectin binding which is absent at early stages (5--6 day old embryos) becomes first detectable at the 7th day and then increases progressively. At day 7, the Con A binding pattern resembles that observed in neuroblastoma cells. The possibility of correlating these surface changes with cell adhesive properties and cell differentiation is discussed.

Carbohydrate Metabolism↗
PubMed1986

Surface modification of soft contact lenses: silanization, wettability and lysozyme adsorption studies.

The surface reactions of poly(2-hydroxyethylmethacrylate) (PHEMA) and the copolymer poly(HEMA-methacrylic acid) (PHEMA/MAA) with methyltrimethoxysilane, ethyltrimethoxysilane and phenyltrimethoxysilane have been characterized by attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy. A model compound, hydroxyethyl isobutyrate was synthesized and subsequently reacted with phenyltrimethoxysilane. Its FTIR spectrum was compared with the ATR-FTIR spectra mentioned above. Protein adsorption experiments showed that silanized PHEMA/MAA soft contact lenses adsorbed less lysozyme than the untreated lenses.

Adsorption↗
PubMed2006

Adsorption of cyanuric acid on activated carbon from aqueous solution: effect of carbon surface modification and thermodynamic characteristics.

The performance of a conventional and two surface-modified activated carbon samples was investigated for the sorption of cyanuric acid from aqueous solution by varying the process parameters such as initial concentration, pH, temperature, dose of adsorbents, and agitation time. The modified carbon samples obtained by acid and ammonia treatment of the conventional sample had a higher BET surface area (989 and 1010 m2 g-1, respectively) and higher specific mesopore surface area (27.36 and 33.21 m2 g-1, respectively) compared to the untreated material (820 and 18.25 m2 g-1). The solute removal was found to be favored at lower solute concentration, increased agitation time, increased adsorbent dose, and lower temperature. The modified adsorbents outperformed the conventional activated carbon for sorption of cyanuric acid especially at higher pH (>7.5) and with increasing temperature. The Freundlich model appears to fit the isotherm data better than the Langmuir model. The thermodynamic parameters (DeltaG degrees ads, DeltaH degrees, and DeltaS degrees) were evaluated showing that the sorption process was thermodynamically favorable, spontaneous, and exothermic. The findings can be used for predictive modeling for analysis and design adsorption systems for removal of cyanuric acid and other polar atrazine degradation products from environmental aqueous samples.

Adsorption↗
PubMedDate not supplied

Improvement of epidermal adhesion by surface modification of craniofacial abutments.

Craniofacial implants may present peri-implant inflammation because there is no close adhesion of the epithelium to abutments and because of bacteria infiltrating the subcutaneous tissue through the gap. Therefore an attempt was made to improve adhesion of epithelium to abutments. In an in vitro model, adhesion of epithelial cells (HaCat cells) to nonmodified and 3 modified Brånemark System abutment surfaces was quantified. It was found that more cells were adherent in sequence at silicone-coated surfaces, sandblasted surfaces, and collagen-coated (Types I and IV) surfaces than on nonmodified abutments. It was concluded that it is possible to improve epidermal adhesion to abutments through modification of abutment surfaces.

Bacterial Physiological Phenomena↗
PubMed1993

Surface modification of the biomedical polymer poly(ethylene terephthalate).

X-ray photoelectron spectroscopy was used to characterize modified surfaces of a biomedically important polymer, poly(ethylene terephthalate). Several modification schemes were investigated and direct silanization with 3-aminopropyltriethoxysilane was found to be the optimum procedure, resulting in an aminated surface. Surface coverage of up to 100% was achieved with retention of the polymeric structural integrity. Further activation of the silanized surface was accomplished with two cross-linkers, glutaraldehyde and sebacoyl chloride. A simple biomolecule, L-cysteine, was successfully immobilized onto a surface pre-treated with 3-aminopropyltriethoxysilane and glutaraldehyde, with a coverage of 42%.

Biocompatible Materials↗
PubMed2007

Surface modification of polymeric biomaterials: utilization of cyclodextrins for blood compatibility improvement.

A novel modified polymeric biomaterial surface using cyclodextrins (CDs) for improved blood compatibility was studied. Plasticized poly(vinyl chloride) (PVC-P) was selected for modification and polyethylene was used as a reference material. The modification was achieved by polymer blending. Fibrinogen and albumin adsorption were utilized as indices for the assessment of the blood compatibility. Surface characterization confirmed that CDs were able to accumulate at the PVC surface and alter the surface properties. The combination of other hydrophilic polymers such as poly(ethylene oxide) (PEO) and PEO/poly(propylene oxide) (PPO) copolymers, such as Pluronic F68 (F68), with CDs were also investigated. These modified materials have a remarkable protein-resistant surface. The combination of B-cyclodextrin (B-CD)/PEO and B-CD/F68 in certain feeding ratio are synergistic in producing enhanced blood compatibility.

Adsorption↗
PubMed2001

The effect of IPN surface modification on the mechanical properties of UHMWPE.

This paper investigates the effect of IPN surface treatment on the mechanical properties of ultra high molecular weight polyethylene (UHMWPE). Traditional UHMWPE was modified by introducing poly-L-lysine (PLL) into their surface and forming a semi-interpenetrating network (IPN). Tensile, creep and fatigue tests were performed on these IPN and the control specimens. The tensile and creep results show that the IPN modification did plasticize the UHMWPE in that it decreased modulus and strength, increased ductility, and degraded creep resistance. However, these property changes are not so large as to be unacceptable. In the fatigue tests, there were no failures of control nor IPN samples up to 10 million cycles.

Coated Materials, Biocompatible↗
PubMed2003

Endothelial cells grown on thin polyelectrolyte mutlilayered films: an evaluation of a new versatile surface modification.

Endothelial cell seeding constitutes an appreciated method to improve blood compatibility of small-diameter vascular grafts. In this study, we report the development of a simple innovative technique based on multilayered polyelectrolyte films as cell adhesive substrates. Polyelectrolyte multilayered films ending by poly(sodium-4-styrenesulfonate)/poly(allylamine hydrochloride) (PSS/PAH) or poly(L-glutamic acid)/poly(D-lysine) (PGA/PDL) could enhance cell adhesion by modification of the physico-chemical properties of the surface. The biological responses of human umbilical vein endothelial cells seeded on the polyelectrolyte multilayer films, on PDL or PAH monolayers, and on control surfaces, were evaluated in terms of initial attachment, growth, cellular metabolic activity, endothelial phenotype, and adhesion. The results showed that polyelectrolyte multilayers neither induce cytotoxic effects nor alter the phenotype of the endothelial cells. The polyelectrolyte multilayered films enhanced initial cell attachment as compared to the polyelectrolyte monolayer. Cell growth observed on the films was similar to that on TCPS. Among the different coating tested, the film ending by PSS/PAH exhibited an excellent cellular biocompatibility and appeared to be the most interesting surface in terms of cellular adhesion and growth. Such films could be used to cover hydrophobic (cell resistant) substrates in order to promote cell colonization, thereby constituting an excellent material for endothelial cell seeding.

Biocompatible Materials↗
PubMed1997

Plasma surface modification of artificial corneas for optimal epithelialization.

We have demonstrated that the optimal surface treatment of a polyvinylalcoholcopolymer hydrogel for epithelial cell migration and proliferation is an argon radio frequency (rf) plasma treatment. The surface chemistry of the material was determined prior to each cellular evaluation, allowing us to compare the biological response with a known surface chemistry. The cellular response was carried out in a consistent manner a minimum of three separate runs. We found that the optimal conditions required culturing the cells under constant rotation. Cells became confluent on argon-plasma-treated surfaces coated under several different reactions pressures, and after 2 weeks they became multilayered. Our experiments demonstrated that cells proliferated and extracellular matrix and adhesion proteins were present only when the surface was treated with an argon rf plasma; acetone- and ammonia-treated surfaces did not yield the desired results. Organ culture experiments further demonstrated the efficacy of the argon-treated surfaces. In these experiments, intact keratoprosthetic devices with modified hydrogel surfaces were implanted into rabbit corneas. The excised corneas containing the devices were cultured, and 3 weeks later, using confocal laser scanning microscopy, confluent epithelium was detected on the modified hydrogel surface. This is the first demonstration that rabbit limbal epithelial cells can migrate onto a synthetic cornea containing a modified hydrogel-treated surface and form a confluent surface of epithelium.

Animals↗
PubMed1994

Surface modification of polymeric biomaterials by albumin grafting using h-irradiation.

Polymeric biomaterial surfaces were modified by albumin grafting to improve their blood compatibility. Albumin molecules were functionalized by introducing double bonds using glycidyl acrylate. The functionalized albumin was covalently attached to various biomaterial surfaces such as polypropylene, polycarbonate, and poly(vinyl chloride) by h-irradiation. Surface-induced platelet adhesion and thrombus formation on the albumin-grafted surfaces was examined using computer-enhanced video microscopy and scanning electron microscopy. The amount of the grafted albumin was dependent on the h-irradiation dose and the concentration of albumin used for adsorption. The grafted albumin molecules remained on the surface even after exposure to blood for prolonged time periods. This approach was used to graft albumin to polymeric materials of an oxygenator. The albumin grafting resulted in a substantial improvement in blood compatibility as compared to control oxygenators. The covalent grafting of functionalized albumin by h-irradiation obviates the need for premodification of chemically inert polymer surfaces. It is useful for albumin grafting to various biomaterial surfaces.

Acrylates↗
PubMed2004

A simple approach to micropatterning and surface modification of poly(dimethylsiloxane).

Ozone treatment is an efficient economical, alternative method for surface activation of poly(dimethylsiloxane) (PDMS). This is illustrated by the derivatization of a PDMS surface with (3-aminopropyl)triethoxysilane (APTES). The apparent surface concentration of amino groups was found to be ca. 10(-8) mol/cm2 using UV/visible spectroscopy of the product from the reaction of the amino groups and fluorescamine. Potential application for micropatterning of biologically active interfaces was demonstrated by the covalent immobilization of oligonucleotides. A simple process for photolithographic patterning on PDMS surfaces has been developed.

Journal Article↗
PubMed2001

Direct electrochemistry of heme proteins: effect of electrode surface modification by neutral surfactants.

Direct electrochemical studies on horse heart myoglobin and horseradish peroxidase (HRP) have been carried out using tin-doped indium oxide (ITO) and surfactant modified glassy carbon working electrodes. These proteins show very slow electron transfer kinetics at metal or untreated electrodes. Moreover, small amounts of surface-active impurity were drastically affects the electrode reaction of these proteins. The results showed that modification of the electrode surface with neutral surfactants significantly improves the electrochemical response of myoglobin as well as of HRP. The electrode response was found to depend on the structure of the surfactants. The amount of surfactant required per unit area of the electrode surface to promote the maximum electron transfer rate constants was found to be constant. This indicated that the surfactant molecules interacted with the electrode surface in a specific manner and anchored the protein molecules to align in the suitable orientation. The hydrophobicity of the surfactants rather than their charge was found to be crucial in promoting the electrode response of these proteins at the glassy carbon electrode.

Animals↗
PubMed2002

Surface modification of superparamagnetic magnetite nanoparticles and their intracellular uptake.

Superparamagnetic magnetite nanoparticles were surface-modified with poly (ethylene glycol) (PEG) and folic acid, respectively, to improve their intracellular uptake and ability to target specific cells. PEG and folic acid were successfully immobilized on the surfaces of magnetite nanoparticles and characterized using fourier transform infrared spectra. The nanoparticle internalization into mouse macrophage (RAW 264.7) and human breast cancer (BT20) cells was visualized using both fluorescence and confocal microscopy, and quantified by inductively coupled plasma emission spectroscopy (ICP). After the cells were cultured for 48 h in the medium containing the nanoparticles modified with PEG or folic acid, the results of fluorescence and confocal microscopy showed that the nanoparticles were internalized into the cells. The ICP measurements indicated that the uptake amount of PEG-modified nanoparticles into macrophage cells was much lower than that of unmodified nanoparticles. while folic acid modification did not change the amount of the uptake. However, for breast cancer cells, both PEG and folic acid modification facilitated the nanoparticle internalization into the cells. Therefore, PEG and folic acid modification of magnetite nanoparticles could be used to resist the protein adsorption and thus avoid the particle recognition by macrophage cells, and to facilitate the nanoparticle uptake to specific cancer cells for cancer therapy and diagnosis.

Animals↗
PubMed2003

Functionalization of poly-(L-lactic-co-epsilon-caprolactone): effects of surface modification on endothelial cell proliferation and hemocompatibility [corrected].

A copolymer of L-lactic acid and epsilon-caprolactone (PLLACL) was synthesized with the aim of preparing a bioartificial, small-diameter and partially resorbable vascular graft. The material was submitted to surface functionalizations (i.e. chemical modification by means of hydrolytic 'etching' and plasma discharge) to promote endothelial cell (EC) adhesion and growth avoiding platelet adhesion or coagulation factor absorption. Furthermore, the behaviour of human microvascular endothelial cells (HMVEC) seeded on the untreated and treated copolymer is described, as well as the platelet adhesion and the modifications of coagulation factors determined by the copolymer itself. PLLACL in its native state provided little support for EC adhesion. Improved EC adherence was obtained when functional groups were provided on the polymer surface by surface chemical hydrolysis. HMVEC seeded and cultured on the polymer surface did not show any ultrastructural alteration, thus demonstrating the absence of the polymer cytotoxicity. Moreover, SEM analysis performed on cold plasma modified specimens showed the presence of a subconfluent monolayer of EC, with an elongated spread morphology. Both the untreated and treated copolymers induced only slight variations of platelet number, but determined the activated partial thromboplastin time (APTT) increase, due to factor XI reduction. Finally, a prototype of partially biodegradable vascular prosthesis was prepared with NaOH/HCl-treated copolymer. Pre-cultured HMVEC seeding of the prosthesis by means of a rotation device resulted in an almost completely coverage of the graft inner surface.

Biocompatible Materials↗
PubMed1994

Surface modification of titanium alloy implants.

Hip replacement stems manufactured from Ti6Al4V titanium alloy were surface treated in one of four ways and tested for dissolution resistance in bovine serum. Those stems treated thermally were found to have significantly lower metal ion release compared with those receiving standard commercial treatments. The improved dissolution behaviour is associated with a change in the surface oxide structure from mixed titanium oxides to a more stable rutile structure.

Adsorption↗
PubMed2003

Surface modification of tricalcium phosphate for improvement of the interfacial compatibility with biodegradable polymers.

The surface of tricalcium phosphate (TCP) filler particles was activated by treatment with dilute aqueous phosphoric acid. ATR-IR spectra indicated the formation of calcium hydrogen phosphate dihydrate at the surface. Oligo(lactone)s were formed by the subsequent reaction of the activated TCP with L-lactide and epsilon -caprolactone, respectively, at 150 degrees C without any additional catalysts. After extraction of the oligo(lactide), the residue of modified TCP-included calcium lactate whereas the water of crystallization of the dihydrate disappeared as shown by ATR-IR spectroscopy. Owing to the insolubility of TCP in common solvents, the analogous reaction between water-soluble disodium hydrogen phosphate dihydrate and L-lactide was used to study the kind of chemical bonds by high-resolution NMR spectroscopy. The 1H and 13C NMR spectra of the reaction product also pointed out the presence of calcium lactate. Additionally, signals were found indicating a covalent attachment of lactic acid units onto the phosphorus. For the preparation of composites, poly(L,DL-lactide) was mixed with TCP and modified TCP, respectively, in a ratio of 75/25 (w/w) and directly injection moulded into tensile test specimens at a barrel temperature of 180 degrees C. Although mechanical properties were not improved, scanning electron microscopy (SEM) indicated a better interfacial phase interaction in the composite with the modified TCP. Chemical bonds between filler and polymer matrix are assumed to be formed by transesterification reactions.

Biocompatible Materials↗
PubMed2003

Surface modification of hydroxyapatite. Part I. Dodecyl alcohol.

The influence of esterification reactions on the surface chemistry and colloid stability of hydroxyapatite (HAP) was studied by aging nanophase HAP in dodecyl alcohol at elevated temperatures (115 degrees C and 190 degrees C). The esterified HAP particles were characterized by X-ray diffraction, transmission electron microscopy, diffuse reflectance infra-red Fourier transform spectroscopy (DRIFTS), thermal gravimetric analysis, sedimentation time studies, and electrophoretic mobility (mu) measurements in water and ethyl alcohol. DRIFTS analysis revealed that the HAP surface was modified by dodecyl groups based on the appearance of C-H stretch vibrational modes at 2962, 2930, and 2860cm(-1). Dodecyl alcohol modified HAP exhibited a larger TGA mass loss upon heating (up to 4.8%) compared to untreated HAP (2.5-3.2wt%). Sedimentation studies revealed the following stability trends: HAP dispersed in water was approximately the same as esterified HAP in water (a few hours) <HAP in ethyl alcohol (1-7 days) << esterified HAP in ethyl alcohol (115 degrees C, 70h; 190 degrees C, over 65 days). The differences in colloid stability are attributed to Lewis acid/base interactions for the untreated HAP and steric stabilization effects for the nanophase HAP with surface dodecyl groups.

Biocompatible Materials↗