SEARCH · PubMed Health

Results for “Polymers”

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 523 records · Page 29Linked to original sources

PubMed1990

Interactions of biospecific functional polymers with blood proteins and cells.

Biospecific functional polymers, i.e. synthetic or artificial polymers substituted with specific chemical functional groups carried by the macromolecular chain are designed to interact with living systems. These polymers are either insoluble or soluble, derived from polystyrene and dextran. Polymers substituted with aryl sulfonate and carboxyl groups specifically interact with antithrombin III and serine-proteases involved in the coagulation of blood. As a consequence, these polymers possess heparin-like activity and are therefore of low thrombogenicity when exposed to flowing blood. Other functional polymers have been prepared in order to interact with various components of the immune system. Soluble and insoluble functional polymers in contact with cells can affect both cell proliferation and metabolism. Some functional polymers have the ability to inhibit or to stimulate cell growth while others can alter cell function without a change in growth characteristics. The functional polymers described have possible applications as plasma expanders, non-thrombogenic catheters, non-complement activating surfaces and other applications in oncology, biotechnology and immunochemistry.

Adsorption↗

PubMed1990

Bacterial polymers: physicochemical aspects of their interactions at interfaces.

How do bacteria stick to a surface? There is still not enough information about to answer this question especially at the molecular level. This question only gives rise to more questions. What is the structure of the true adhesive bacterial polymer? Is only one bacterial polymer or several polymers involved in the adhesion process? What is the role of proteins associated with the bacterial polysaccharides? What type of polymer is produced for the adhesion to hydrophobic surfaces? Is the polymer produced as a response to the surface? This review is an attempt to summarize the physicochemical aspects of bacterial polymers and their interaction with surfaces. It was tried to give an overview of the literature published in this field. The article is divided into the following sections: first, the forces involved in bacterial adhesion are discussed. Third, different fluid conditions are investigated. Fourth, the nature of different bacterial polymers which are important for the interaction with a surface is elaborated. Fifth, the current knowledge about biological polymers at interfaces is shown. And sixth, the role of polymers in the adhesion of bacteria available to date is highlighted.

Bacterial Adhesion↗

PubMed2003

Biodegradable synthetic polymers for tissue engineering.

This paper reviews biodegradable synthetic polymers focusing on their potential in tissue engineering applications. The major classes of polymers are briefly discussed with regard to synthesis, properties and biodegradability, and known degradation modes and products are indicated based on studies reported in the literature. A vast majority of biodegradable polymers studied belongs to the polyester family, which includes polyglycolides and polylactides. Some disadvantages of these polymers in tissue engineering applications are their poor biocompatibility, release of acidic degradation products, poor processability and loss of mechanical properties very early during degradation. Other degradable polymers such as polyorthoesters, polyanhydrides, polyphosphazenes, and polyurethanes are also discussed and their advantages and disadvantages summarised. With advancements in tissue engineering it has become necessary to develop polymers that meet more demanding requirements. Recent work has focused on developing injectable polymer compositions based on poly (propylene fumarate) and poly (anhydrides) to meet these requirements in orthopaedic tissue engineering. Polyurethanes have received recent attention for development of degradable polymers because of their great potential in tailoring polymer structure to achieve mechanical properties and biodegradability to suit a variety of applications.

Biocompatible Materials↗

PubMedDate not supplied

Polymer-coated long-circulating microparticulate pharmaceuticals.

The field of long-circulating microparticulate drug carriers is reviewed. The protective effect of certain polymers including poly(ethylene glycol) on nanoparticulate carriers (liposomes, nanoparticles, micelles) is considered in terms of statistical behaviour of macromolecules in solution. Using liposomes as an example, the mechanism is discussed assuming that surface-grafted chains of flexible and hydrophilic polymers form dense 'conformational clouds' preventing other macromolecules from interaction with the surface even at low concentrations of the protecting polymer. The scale of the protective effect is interpreted as the balance between the energy of the hydrophobic anchor interaction with the liposome membrane core or with the particle surface and the energy of the polymer chain free motion in solution. The possibility of using protecting polymers other than poly(ethylene glycol) is analysed, and examples of such polymers are given, based on polymer-coated liposome biodistribution data. General requirements for protecting polymers are formulated. Sterically protected nanoparticles and micelles are considered, and differences in steric protection of liposomes and particles are discussed. The problem of the preparation of drug carriers combining longevity and targetability is analysed. The biological consequences of steric protection of drug carriers with surface-grafted polymers are discussed, and possible clinical applications for long-circulating pharmaceutical carriers are considered.

Animals↗

PubMed2001

Hematological effects and metal residue concentrations following chronic dosing with tungsten-iron and tungsten-polymer shot in adult game-farm mallards.

The U.S. Fish and Wildlife Service required a chronic dosing study that assessed the health and reproductive effects of tungsten-iron and tungsten-polymer shot in adult game-farm mallards (Anas platyrhynchos) prior to granting permanent approval of the shot for waterfowl hunting. Herein, we present the effects of tungsten-iron and tungsten-polymer shot on various hematologic parameters and metal residue concentrations in the femur, liver, kidneys, and gonads. Thirty-two-bird groups (sexes equal) of adult mallards were dosed orally with eight #4 steel shot (control), eight #4 tungsten-iron shot, or eight #4 tungsten-polymer shot on days 0, 30, 60, 90, and 120 of a 150 day trial (26 January 1998 to 25 June 1998). An additional 12 mallards (sexes equal) received eight #4 lead shot (positive control) on day 0 of the study. Lead-dosed mallards had significantly decreased hematocrit, hemoglobin concentration, and whole-blood delta aminolevulinic acid dehydratase activity on day 7, as well as significant changes in a number of plasma chemistry parameters compared to ducks in the control, tungsten-iron, or tungsten-polymer groups. Mallards dosed with tungsten-iron or tungsten-polymer shot had occasional significant differences in hematocrit and plasma chemistry values when compared to control mallards over the 150 day period, but these changes were not considered to be indicative of deleterious effects. Low concentrations of tungsten were detected in gonad and kidney samples from males and females and in liver samples from females dosed with tungsten-polymer shot. Tungsten was also detected in femur samples from tungsten-polymer-dosed mallards. Higher concentrations of tungsten were detected in femur, liver, kidney, and gonad samples from tungsten-iron-dosed ducks. Tungsten-iron or tungsten-polymer shot repeatedly administered to adult mallards did not cause adverse hematological effects during the 150 day trial. Concentrations of tungsten in the femur, liver, kidneys, and gonads were generally higher in tungsten-iron-dosed ducks when compared to tungsten-polymer-dosed ducks.

Animals↗

PubMed2001

Effect of water-soluble polymers on naproxen complexation with natural and chemically modified beta-cyclodextrins.

The combined effect of cyclodextrins (CDs) (beta-, methyl-beta-, hydroxypropyl-beta-cyclodextrins) and water-soluble polymers (sodium carboxymethylcellulose, hydroxypropylmethylcellulose, polyvinylpyrrolidone K30, polyethylene glycol 6000) on naproxen solubility improvement was studied. Phase solubility analysis at 25 degrees C was used to investigate the interaction of the drug with each cyclodextrin (or polymer, alone or in the presence of the different water-soluble polymers (or cyclodextrins). The combined use of polymer and cyclodextrin was always clearly more effective in enhancing the aqueous solubility of naproxen in comparison with the corresponding drug-polymer or drug-cyclodextrin binary systems, and the solubilization enhancement was not simply additive, but synergistic. Water-soluble polymers increased the complexation efficacy of cyclodextrins toward naproxen (as shown by the increased stability constants of the complexes), which resulted in enhanced drug solubility. No previous sonication or heating treatments of the drug-cyclodextrin-polymer suspensions was necessary to obtain this favorable effect. The best results were obtained in ternary systems with beta-cyclodextrin, which had a solubilizing effect toward naproxen in the presence of 0.25% w/v of the different hydrophilic polymers examined that was improved from 25% to about 80%, depending on the type of polymer.

Cyclodextrins↗

PubMed2005

[The erosion behaviour of matrix tablets using polyethylene oxide matrices as hydrophilic polymer].

AIM: To study the erosion behaviour during dissolution of matrices using different molecular weight polyethylene oxide (PEO) as hydrophilic polymer. METHODS: PEO hydrophilic matrix tablets with no added drug and excipients were prepared by direct compression method. The erosion rates of matrices comprised of pure or blending PEO polymers were evaluated in distilled water at (37 +/- 0.5) degrees C with rotating rate of 50 r x min(-1). The relationship between PEO molecular weight and erosion rate of matrices was investigated by experimental and mathematical model methods. RESULTS: The gravimetric erosion experimental results indicated that the power-law relationship which relates the polymer erosion rate and weight average molecular weight: k infinity (M(w)) -1.30 4 was proved to have great potential utility in predicting the degree of polymer erosion of matrices comprised of either intermediate molecular weight (97. 98 x 10(4) - 553. 36 x 10(4)) or blends of lower and higher molecular weight polymers. Based on the semiempirical equation for mass transfer rate: Jp = (fp < Dp > (2/3) v (-1/6) omega (1/2)) C(p,dis), a theoretical mathematic model was developed for describing the relationship between PEO erosion rate and PEO weight average molecular weight: Jp infinity M(-1.241), where the exponent of -1. 241 was very close to the exponent of - 1. 130 4 obtained from practical determination. CONCLUSION: PEO was proved to be a good candidate of hydrophilic polymer and appeared to have great potential for controlled release applications. The mathematic model presented together with the utilization of the erosion behaviour discussed in our study could provide a guide line to predict the degree of polymer erosion for other intermediate polymer grades and / or mixture of the polymers utilized in this study, which could play an active role in designing PEO hydrophilic sustained delivery systems.

Delayed-Action Preparations↗

PubMed1991

Isolation from commercial aurintricarboxylic acid of the most effective polymeric inhibitors of von Willebrand factor interaction with platelet glycoprotein Ib. Comparison with other polyanionic and polyaromatic polymers.

Solutions of commercial aurintricarboxylic acid (ATA) inhibit ristocetin- or shear stress-induced, von Willebrand factor (vWF)-mediated platelet aggregation by interacting with vWF and blocking its attachment to platelet membrane glycoprotein Ib. ATA has also been shown to prevent cyclic platelet clumping in a dog model of coronary artery thrombosis. Because these ATA solutions are actually a heterogeneous mixture of polyanionic, polycarboxylic polyaromatic polymers of molecular weight (Mr) 200 to greater than 6,000, we separated the most effective inhibitory components of commercial ATA using exclusion chromatography. ATA polymers larger than Mr 700 inhibited ristocetin-induced, vWF-mediated platelet aggregation more effectively than smaller ATA polymers, whereas shear-induced, vWF-mediated platelet aggregation was optimally inhibited by ATA polymers of Mr greater than or equal to 2,500. Platelet aggregation mediated by vWF was not inhibited by a nonphenolic, polyanionic polymer (polyglutamic acid) or by a polyphenolic ATA-like polymer (aurin) devoid of carboxyl groups. Polyanionic, polysulfonated aromatic polymers (polystyrene sulfonate) of Mr 35, 17.4, 8, and 4.6 x 10(3) inhibited ristocetin- and shear-induced, vWF-mediated aggregation with less potency on a mass/volume basis than large polymers of ATA. We conclude that a polyanionic, polycarboxylated, polyphenolic ATA polymer of Mr 2,500 is optimally potent as an inhibitor of shear- and ristocetin-induced, vWF-mediated platelet aggregation and is likely to be more effective than solutions of commercial ATA as an anti-arterial thrombotic agent.

Adenosine Diphosphate↗

PubMed1988

Binding of acrylic polymers to mucin/epithelial surfaces: structure-property relationships.

Bioadhesion, and more specifically mucoadhesion, is becoming an important strategy for drug delivery. As a result, it is important to understand the various mechanisms that govern attachment of polymeric substances to the glycoproteins on epithelial surfaces, along with the associated structure-activity relationships of the polymer. This article reviews fundamentals of mucoadhesion, with special emphasis on structural features of the polymer as they contribute to the process of mucoadhesion. There are four possible general interactions between mucoadhesive polymers and glycoproteins: (1) covalent attachment; (2) electrostatic interaction, which requires matching of charge groups between the polymer and mucus; (3) hydrogen bonding; and (4) hydrophobic interactions. Aside from covalent attachment, which is not presently a prominent mechanism for mucoadhesion, the remaining mechanisms require maximum contact between the polymer and mucin for optimum adhesion. With polyelectrolyte polymers, the charged groups are important in controlling the degree of hydration of both the polymer and the mucous network. The expanded nature of the swollen polymer and mucus enhances the interdiffusion process and permits both a mechanical entanglement and an increase in surface contact for hydrogen bonding and/or electrostatic interaction between the polymer and the mucous network. A number of techniques are available to study mucoadhesion. Some of these are better suited to study the kinetics of the mucoadhesion process whereas others are more useful for equilibrium studies. To date, the major deficiency in basic studies of mucoadhesion is the lack of suitable information on the organization and physicochemical properties of the mucin layer.

Acrylates↗

PubMed1995

Feasibility of electrophoresis of a subcellular-sized particle in polymer solutions, using automated horizontal gel apparatus.

Electrophoresis in polymer solutions of a fluorescently labeled polystyrene carboxylate particle of 46.5 nm radius was carried out in a horizontal gel electrophoresis apparatus with intermittent scanning of the migration path. Polymers of the order of 10(6) (dextran, polyvinylpyrrolidone, polyacrylamide and polyethyleneglycol) and 10(5) (hydroxyethylcellulose, polyethyleneglycol) M(r) were used. In each application, bands formed, became symmetric and narrowed with increasing polymer concentration. The decrease in dispersion coefficients, D', with polymer concentration was sharpest with the polymers of M(r) 10(6); but significant differences in the effectiveness of polymers within that group also exist which are not accounted for. Provided that the demonstrated feasibility of banding in concentrated polymer solutions will allow for separations similar to those achieved at low polymer concentrations in CZE, the method promises to overcome the inherent shortcomings of capillary electrophoresis in polymer solutions with regard to inaccessibility of bands for immunological and affinity detection as well as to preparative scale and preparative instrumental complexity.

Automation↗

PubMed1997

Retinal pigment epithelium cells cultured on synthetic biodegradable polymers.

Alterations in the normal structure or functions of retinal pigment epithelium (RPE) can result in a number of ocular diseases. Implantation of RPE cells cultured on thin, biodegradable polymer films may provide a means of transplanting an organized sheet of RPE cells with distinct apical/basal characteristics for the restoration of normal RPE function. We have investigated the interactions of human RPE cells with different biodegradable polymer films to assess their suitability as substrates for RPE culture. Four biodegradable polymers were used: low molecular weight (MW) 50:50 poly(DL-lactic-co-glycolic acid) (PLGA); high MW 50:50 PLGA; 75:25 PLGA; and poly(L-lactic acid) (PLLA). Polymer film substrates were manufactured using a solvent casting technique. Human fetal RPE cells (10-16 weeks gestational) were plated on the polymer substrates and the cultures assessed with respect to cell attachment and proliferation. Histological and immunohistochemical studies were performed on the cells after 8 days in culture. RPE cells attached to all the polymers studied after 8 h in culture. After 8 h, 80.2 +/- 9.5% and 82.3 +/- 7.9% of the plated cells were attached to substrates of high MW 50:50 PLGA and 75:25 PLGA, respectively. The cells proliferated on all substrates, and there was about a threefold increase in cell number over the 8-day culture period on all the polymers studied. Immunohistochemistry after 8 days in culture demonstrated RPE cells labeled with a distinct reaction product for cytokeratin in the cell cytoplasm. All the polymers studied were suitable for RPE culture; however, high MW 50:50 PLGA and 75:25 PLGA proved to be the best in terms of manufacturing properties, cell attachment, and proliferation. These polymers can provide a suitable substrate for RPE cell culture and hold promise for the subretinal implantation of organized sheets of RPE cells.

Biodegradation, Environmental↗

PubMed1998

Quantification and localization of hyaluronan in a PTFE polymer implanted in the corneal stroma.

The amount and distribution of hyaluronan in a PTFE polymer used to support an artificial cornea implanted in the rabbit cornea were determined. The findings were used to describe the polymer-corneal stroma interface and the reason for the translucence and wettability of this originally opaque and hydrophobic biomaterial. PTFE disks (6 mm in diameter, 0.2 mm thick, 50 microns in pore size) were implanted after a free-hand intralamellar dissection. The corneas were removed 15 days, 1 month, and 3 months after implantation. The hyaluronan content of pepsin-solubilized corneal stromal extracts and its distribution (7 microns cryostat sections) were investigated using an alkaline phosphatase-linked hyaluronectin assay that specifically detects nanogram amounts of hyaluronan. A PTFE polymer implant caused large, transient increases in hyaluronan density in the implanted stroma. The presence of amphiphilic hyaluronan in the polymer 15 days post implantation probably produced translucence and wettability of this opaque, hydrophobic implant despite the absence of cells. The hyaluronan density in the PTFE polymer increased considerably during the first month and then decreased to stabilize at a moderate level by the third month. These changes in hyaluronan density parallel the invasion of the polymer by inflammatory cells during the first month and the subsequent replacement of these cells by fibroblasts. The PTFE polymer is a good interface that is compatible with the native corneal stroma, and our results indicate that hyaluronan, because of its amphiphilic character, plays a major role in the polymer wettability and translucence and in the production of typical corneal extracellular matrix within the pores of the polymer.

Alkaline Phosphatase↗

PubMed1998

Short-term in vivo evaluation of small-diameter vascular prosthesis composed of segmented poly(etherurethane)/2-methacryloyloxyethyl phosphorylcholine polymer blend.

A small-diameter vascular prosthesis with potential for clinical use was prepared from a Dacron prosthesis coated with nonthrombogenic polymeric materials. As a coating material, segmented poly(etherurethane) (SPU; Tecoflex 60) was blended with a phospholipid polymer, 2-methacryloyloxyethyl phosphorylcholine (MPC) polymer, which has excellent blood compatibility. The Dacron prosthesis, 2 mm in diameter, was immersed in a solution of the SPU/MPC polymer blend and dried to evaporate the solvent. The SPU/MPC polymer prosthesis was nonwater permeable and could be sewn to a natural vessel by a microsurgical technique. The SPU solution was used instead of the SPU/MPC polymer blend solution to prepare a control prosthesis (SPU prosthesis). The SPU/MPC polymer prosthesis and the SPU prosthesis were placed as interposition grafts in rabbit carotid arteries. A massive red thrombus became attached to the surface of the SPU prosthesis as early as 90 min after implantation. In the SPU/MPC polymer prosthesis case, the surface was maintained clear even after 5-day implantation. These observations indicated that the MPC polymer in the SPU could improve the nonthrombogenicity of SPU, and the SPU/MPC polymer blend had potential for preparation of small-diameter vascular prostheses.

Animals↗

PubMed1999

In vitro modulation of macrophage phenotype and inhibition of polymer degradation by dexamethasone in a human macrophage/Fe/stress system.

A new in vitro accelerated biological model, the macrophage-FeCl2-stress system was used for the evaluation of dexamethasone (DEX)-polymer formulations. This model combines the effects of cells (macrophages), transition metal ions (Fe2+), and polymer stress to promote material biodegradation. The cell and material effects of DEX, either in solution or incorporated into a polyetherurethane matrix (DEX/PEU), were monitored. Cell morphology and hydroperoxide formation in the polymer during cell culturing were characterized. After a subsequent treatment with FeCl2 the development of environmental stress cracking in the polymer was evaluated. We attempted to duplicate the biodegradation of PEU in terms of environmental stress cracking (ESC). Our results support the direct involvement of macrophages in polyetherurethane oxidation, probably by inducing hydroperoxide formation in the polymer structure. Under the influence of stress or strain, polymers with sufficient hydroperoxides degrade in the presence of Fe2+ metal ions in a manner that closely resembles the stress cracking that is observed in vivo. By contrast, polymers treated with either agents that inhibit cell activation and/or the oxidative burst, or with cells with no oxidative burst did not show signs of the biodegradative process. We demonstrated a reduction in hydroperoxide formation and no later ESC development in macrophage-cultured PEU in the presence of DEX in solution or in DEX-loaded PEU. We believe the prevention of initial polymer oxidation by reducing the cell's potential to produce oxidative stress at the tissue-biomaterial interface can directly inhibit the ESC degradation of chronically implanted polymers. The in vitro macrophage-Fe-stress system is a valuable tool for reliable assessment and cost-effective evaluation of biomaterials.

Adult↗

PubMed2001

Interaction of sulfonylurea-conjugated polymer with insulinoma cell line of MIN6 and its effect on insulin secretion.

A carboxylated derivative of sulfonylurea (SU), an insulinotropic agent, was synthesized and grafted onto a water-soluble polymer as a biospecific and stimulating polymer for insulin secretion. To evaluate the effect of the SU-conjugated polymer on insulin secretion, its solution in dimethyl sulfoxide was added to the culture of insulinoma cell line of MIN6 cells to make 10 nM of SU units in the medium and incubated for 3 h at 37 degrees C. The culture medium was conditioned with glucose concentration of 3.3 or 25 mM. To verify the specific interaction between the SU (K+ channel closer)-conjugated polymer and MIN6 cells, the cells were pretreated with diazoxide, an agonist of adenosine triphosphate-sensitive K+ channel (K+ channel opener), before adding the SU-conjugated polymer to the cell culture medium. This treatment suppressed the action of SUs on MIN6 cells. Fluorescence-labeled polymer with rodamine-B isothiocyanate was used to visualize the interactions, and we found that the labeled polymer strongly absorbed to MIN6 cells, probably owing to its specific interaction mediated by SU receptors on the cell membrane. The fluorescence intensity on the cells significantly increased with an increase in incubation time and polymer concentration. A confocal laser microscopic study further confirmed this interaction. The results from this study provided evidence that SU-conjugated copolymer stimulates insulin secretion by specific interactions of SU moieties in the polymer with MIN6 cells.

Acrylic Resins↗

PubMed2001

Impact of polymer hydrophobicity on the properties and performance of DNA sequencing matrices for capillary electrophoresis.

To elucidate the impact of matrix chemical and physical properties on DNA sequencing separations by capillary electrophoresis (CE), we have synthesized, characterized and tested a controlled set of different polymer formulations for this application. Homopolymers of acrylamide and N,N-dimethylacrylamide (DMA) and copolymers of DMA and N,N-diethylacrylamide (DEA) were synthesized by free radical polymerization and purified. Polymer molar mass distributions were characterized by tandem gel permeation chromatography - laser light scattering. Polymers with different chemical compositions and similar molar mass distributions were selected and employed at the same concentration so that the variables of comparison between them were hydrophobicity and average coil size in aqueous solution. We find that the low-shear viscosities of 7% w/v polymer solutions decrease by orders of magnitude with increasing polymer hydrophobicity, while hydrophilic polymers exhibit more pronounced reductions in viscosity with increased shear. The performance of the different matrices for DNA sequencing was compared with the same sample under identical CE conditions. The longest read length was produced with linear polyacrylamide (LPA) while linear poly-N,N-dimethylacrylamide (PDMA) gave approximately 100 fewer readable bases. Read lengths with DMA/DEA copolymers were lower, and decreased with increasing DEA content. This study highlights the importance of polymer hydrophilicity for high-performance DNA sequencing matrices, through the formation of robust, highly-entangled polymer networks and the minimization of hydrophobic interactions between polymers and fluorescently-labeled DNA molecules. However, the results also show that more hydrophobic matrices offer much lower viscosities, enabling easier microchannel loading at low applied pressures.

Acrylamides↗

PubMed1993

Effects of phospholipid adsorption on nonthrombogenicity of polymer with phospholipid polar group.

Polymers with phospholipid polar groups, 2-methacryloyloxyethyl phosphorylcholine (MPC) polymers, have excellent nonthrombogenic properties. The effects of adsorption of phospholipids on platelet adhesion and activation on the MPC copolymer with n-butyl methacrylate (BMA) were investigated with particular attention to the structure of the phospholipids adsorbed onto the polymer surface. The electrical nature of the phospholipids adsorbed on the polymer surface affected the thrombogenicity of the polymer. On the MPC polymer surface treated with an aqueous liposomal solution of acidic phospholipids, phosphatidylserine, platelet adhesion and activation occurred to a greater extent when compared to a poly(MPC-co-BMA) surface. However, on the MPC polymer surface treated with electrically neutral phosphatidylcholines, reduced thrombogenicity could be observed. Therefore, the adsorption of the phosphatidylcholines was an important factor in reducing the thrombogenicity on the polymers. Moreover, by comparison of the poly(MPC-co-BMA) to a poly(BMA), platelet adhesion and activation on these polymer surfaces depended on the adsorption state of the phosphatidylcholines. The amount of phosphatidylcholine adsorbed on the poly(MPC-co-BMA) increased with an increase in the MPC mole fraction of the copolymer. This indicates that the MPC moieties have affinity for the phosphatidylcholines. We conclude that the poly(MPC-co-BMA) can adsorb large amounts of phosphatidylcholines and that these phospholipids organize themselves. The organized adsorption layer of the phosphatidylcholines on the surface, which construct biomembrane-like surfaces, can reduce platelet adhesion and activation effectively.

1,2-Dipalmitoylphosphatidylcholine↗

PubMed1995

Human monocyte/macrophage adhesion and cytokine production on surface-modified poly(tetrafluoroethylene/hexafluoropropylene) polymers with and without protein preadsorption.

To study surface property-dependent human monocyte adhesion and cytokine (IL-1 beta, IL-6, TNF-alpha) production, poly(tetrafluoroethylene/hexafluoropropylene) (FEP) polymer was modified to exhibit neutral, anionic, or cationic properties by incorporating amide (CONH2) and/or carboxyl (COOH) or aminoethyl amide [CONH(CH2CH2NH)nCH2CH2NH2] groups on the surface. Monocyte adhesion on surface-modified FEP polymers and cytokines released by monocytes/macrophages (MC/MO) into the culture medium were compared to control tissue culture polystyrene (TCPS) at days 1 and 8. On day 1, the neutral surface FEP polymer with incorporated amide (NH2) groups showed the greatest inhibition of adhesion, 89% (P < .01), and cytokine production (IL-1 beta with 58%, IL-6 with 70%, and TNF-alpha with 39%) compared to control TCPS. In contrast, the highly cationic [CONH(CH2CH2NH)nCH2CH2NH2] surface did not show significant (P > .01) inhibition of monocyte adhesion and cytokine production. When fibrinogen or IgG was preadsorbed to the surface, the inhibitory effects of the neutral surface FEP polymer on monocyte adhesion and cytokine production were not altered. In addition, other surface-modified FEP polymers showed similar inhibition of monocyte adhesion and cytokine production compared to TCPS. Specifically, as the incorporation of carboxyl (COOH) group content increased on FEP polymer surfaces, monocyte adhesion and cytokine production were also increased on day 1 with IgG preadsorption. On day 8, all surface-modified FEP polymers showed significant (P < .01) inhibition of monocyte adhesion when fibrinogen or IgG was preadsorbed. However, without protein (fibrinogen or IgG) preadsorption, monocyte adhesion was not significantly inhibited compared to control TCPS. In addition, cytokine production detected by ELISAs on day 8 showed no detectable levels of IL-1 beta and significantly decreased levels of IL-6 compared to day 1 for all tested polymers, with or without protein preadsorption. Interestingly, the level of TNF-alpha production on day 8 remained high although not as high as on day 1. Based on these results, we suggest that FEP polymers with neutral hydrophilic surface properties may adhere and activate the least number of monocytes, which are important mediators of biocompatibility.

Adsorption↗