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Results for “Polystyrenes”

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PubMed1989

In vitro and ex vivo platelet interactions with hydrophilic-hydrophobic poly(ethylene oxide)-polystyrene multiblock copolymers.

Hydrophilic-hydrophobic multiblock copolymers synthesized from telechelic oligomers of poly(ethylene oxide) (PEO) and polystyrene (PS) have been used to study the influence of hydrophilic and hydrophobic balance on interfacial interactions of these surfaces with blood components. In vitro coagulation assays show no inherent ability of these amphiphilic surfaces to affect contact activation or coagulation factors. In vitro platelet adhesion and release reactions from rabbit platelet-rich plasma were shown to be greatest on Biomer and PS homopolymer surfaces and least on cross-linked PEO surfaces, with the PEO-PS block copolymers demonstrating intermediate responses. These same substrates were tested in a new low-flow, low-shear arterio-artery shunt system in rabbits. Whole blood occlusion times were not a direct function of hydrophilic content as both PEO and PS homopolymers and Biomer showed short occlusion times, while PEO-PS block copolymers prolonged occlusion times considerably, depending on composition. Overall, results suggest that PEO-PS block copolymers promote unique whole blood responses in contrast to homopolymer and Biomer controls which are more complex than direct correlations to bulk hydrophilic and hydrophobic contents.

Anastomosis, Surgical↗

PubMed1990

Radiofrequency plasma deposition of oxygen-containing films on polystyrene and poly(ethylene terephthalate) substrates improves endothelial cell growth.

Polystyrene and poly(ethylene terephthalate) substrates were modified by radiofrequency plasma deposition with organic vapors comprised of carbon, oxygen, and hydrogen (acetone, methanol, glutaraldehyde, formic acid, allyl alcohol, and ethylene oxide). The treatments resulted in the deposition of a film at least 100 A thick containing up to 26% atomic oxygen at the surface. A high oxygen incorporation was observed for vapors with a large oxygen-to-carbon ratio. Bovine aortic endothelial cell growth measured on acetone, methanol, and glutaraldehyde films was linearly correlated with the oxygen content of the treated surfaces. Nitrogen was incorporated in the surface by blending nitrogen gas into the organic vapor used for plasma deposition. The resulting nitrogen-containing substrates exhibited a high affinity for serum fibronectin but a moderate cell growth.

Adsorption↗

PubMed1992

Decreased neutrophil respiratory burst on exposure to cobalt-chrome alloy and polystyrene in vitro.

The effect of biomaterials on the superoxide-producing ability of neutrophils was studied. Human peripheral blood neutrophils were incubated with cobalt-base alloy (F-75) or polystyrene beads of a nonphagocytosable size. Respiratory burst activity was studied by measuring superoxide dismutase inhibitable reduction of cytochrome C. Neutrophils were found to release no more superoxide anion on incubation for up to 3 h with either material in a protein-free medium than controls without foreign material. However, the ability of neutrophils incubated with either biomaterial to subsequently respond to phorbol myristate acetate challenge was decreased (p less than 0.05). Chemical analysis of supernatants for the F-75 samples showed a high concentration of cobalt in the medium within 1 h of incubation. Minimal chromium and nickel was detected. No correlation could be demonstrated between metal in solution and the respiratory burst defect in neutrophils. Instead it appears that interaction of cells with either surface was the critical event in altering the response to phorbol myristate acetate. This observed functional defect may play an important role in rendering tissue around implanted biomaterials susceptible to infections.

Adult↗

PubMed1993

A novel recovery system for cultured cells using plasma-treated polystyrene dishes grafted with poly(N-isopropylacrylamide).

Poly(N-isopropyl acrylamide) (PIPAAm) demonstrated a fully expanded chain conformation below 32 degrees C and a collapsed, compact conformation at high temperatures. This unique temperature responsive polymer was grafted onto surfaces of commercial polystyrene dishes and used as temperature switches for creating hydrophilic surfaces below 32 degrees C and hydrophobic surfaces above 32 degrees C. Cell attachment and the growth of bovine endothelial cells and rat hepatocytes on PIPAAm-grafted surfaces at 37 degrees C demonstrated similar behavior to the commercialized culture dishes. Both cell types were observed to detach from the PIPAAm-grafted surface simply by reducing the temperature below the polymer transition temperature (collapse). Cells recovered by this method maintained substrate adhesivity, growth, and secretion activities nearly identical to those found in primary cultured cells in contrast to the compromised function found in cultured cells damaged by trypsinization. These results provide strong evidence that PIPAAm-grafted surfaces, as thermal switches are very effective for reversing cell attachment and detachment without cell damage. Properties of cell culture surfaces can be readily transformed by this technique reversibly into hydrophilic and hydrophobic coatings of PIPAAm-grafted polymers.

Acrylic Resins↗

PubMed1994

Inhibition of platelet spreading from plasma onto glass by an adsorbed layer of a novel fluorescent-labeled poly(ethylene oxide)/poly(butylene oxide) block copolymer: characteristics of the exclusion zone probed by means of polystyrene beads and macromolecules.

We have investigated the anti-adhesive properties of a newly synthesized fluorescent triblock copolymer containing poly(ethylene oxide). This adsorbs from aqueous solution onto glass that has been rendered hydrophobic. When the polymer-treated surface was exposed to human platelet-rich plasma (PRP) or whole blood at 37 degrees C, platelet adhesion and spreading were prevented. Avid adhesion and rapid platelet spreading occurred along tracks scraped in the adsorbed polymer coating, as seen by video-enhanced interference reflection microscopy. Leukocytes from whole blood are eventually able to adhere to the polymer-treated surface and were seen to remove labeled polymer from their vicinity and accumulate it at the cell body. Interferometry using polystyrene spheres showed that they do not adhere to polymer-coated glass and are unable to approach closer than 70-95 nm. On scraped tracks, beads make molecular contacts with the glass. Because the fully extended solvated (EO)400 arms may extend up to 100 nm from the glass, this suggests that the polymer forms a monolayer with the hydrophilic arms projecting into the water, whereas the hydrophobic (BO)55 segment binds the molecule to the hydrophobic surface. Another tri-bloc copolymer with shorter hydrophilic arms allows particles to approach more closely.

Adsorption↗

PubMed2003

Variations in the ability of adsorbed fibrinogen to mediate platelet adhesion to polystyrene-based materials: a multivariate statistical analysis of antibody binding to the platelet binding sites of fibrinogen.

Platelet adhesion to the surfaces of biomaterials preadsorbed with plasma previously has been shown to be mediated exclusively by surface-bound fibrinogen and does not seem to involve the other adhesion proteins in plasma (Tsai et al., J Biomed Mater Res 2002;60:348-359). In this study, the influence of surface-bound fibrinogen on platelet adhesion to five different types of polystyrene-based microtiter plates preadsorbed with plasma was analyzed relative to the amount of adsorbed fibrinogen and monoclonal antibody binding to the adsorbed fibrinogen. There was no significant correlation between platelet adhesion and the absolute amount of adsorbed fibrinogen. However, platelet adhesion was positively correlated to the ability of the adsorbed fibrinogen to bind three types of monoclonal antibodies. The antibodies used bound to the sites on fibrinogen thought to be involved in platelet binding (the two gamma chain C-terminal dodecapeptides and the RGDF and RGDS sequences in each of the Aalpha chains). A partial least-squares calibration model was used to analyze the relative importance of these binding sites in fibrinogen to platelet adhesion. The gamma chain C-terminal dodecapeptide was shown to be the most important site in adsorbed fibrinogen in mediating platelet adhesion.

Adsorption↗

PubMed2004

Polyethylene glycol-grafted polystyrene particles.

Densely pegylated particles that can serve as a model system for artificial cells were prepared by covalently grafting amino polyethylene glycol (PEG, molecular weight 3400 or 5000) onto carboxyl polystyrene particles (PS-COOH) using carbodiimide chemistry. PEG-modified particles (PS-PEG) were characterized by determination of the PEG surface concentration, zeta-potential, size, and morphology. Under optimized grafting conditions, a dense "brush-like" PEG layer was formed. A PEG surface concentration of approximately 60 pmol/cm2, corresponding with an average distance between grafted PEG chains of approximately 17 A can be realized. It was shown that grafting of PEG onto PS-COOH reduced the adsorption of proteins from human plasma (85 vol %) in phosphate-buffered saline up to 90%.

Adsorption↗

PubMed2004

Effects of laser-modified polystyrene substrate on CHO cell growth and alignment.

Biomaterial surface chemistry and nanoscale topography of biomaterials can significantly influence cell behavior in vitro. Polystyrene (PS) Petri dishes were subjected to Nd:YAG laser irradiation at 266 nm, which resulted in well-defined three-dimensional (3D) periodic nanoscale surface topographies and surface oxidation. The surface changes were analyzed by X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), and a contact-angle goniometer. The samples were then used to investigate the cell behavior of Chinese hamster ovary (CHO) cells. The surface laser modification affected the CHO cell adhesion and alignment, and caused morphological changes in comparison with unmodified PS. The results obtained from the cell-behavior studies revealed that nanoscale hydrophilic surface topography cues affected the adhesion, extension, alignment, and morphology of cells.

Animals↗

PubMed1978

Effects of albumin on the phagocytosis of polystyrene spherules by rabbit polymorphonuclear leucocytes.

Polystyrene latex spherules are rapidly phagocytized by polymorphonuclear leucocytes. Surface modifications of the latex spherules can lead to an inhibition of phagocytosis, and the purpose of this study was to analyse in particular inhibition by bovine and human serum albumin. It can be shown that albumin is bound much more strongly by the PSL particle surface than by the cell surface. Furthermore, a correlation was established between the extent to which the particle surface is covered and the extent of phagocytosis inhibition. In the binding of albumin to the particle surface ionic as well as hydrophobic interactions play a role. As a result, the particle acquires a negatively charged hydrophilic coating which effectively diminishes the number of effective cell-particle collisions leading to engulfment.

Animals↗

PubMed1992

The use of modified divinylbenzene-polystyrene resins in the separation of fermentation products. A case study utilizing amino acids and a dipeptide.

The adsorption of phenylalanine, aspartic acid, asparagine and aspartame from phosphate-buffered aqueous solutions with modified divinyl-benzene-polystyrene resins has been investigated using high pressure liquid chromatography (HPLC). The pH studied was 2.8, the temperature range was 293-313 K and the ionic strength was maintained at 1.0 mol dm-3. Over the range of variables investigated, the adsorption isotherms are linear and may be characterized by temperature and pH-dependent apparent adsorption equilibrium constants, characteristic of the resin-adsorbate system. By studying the dependence on temperature of this adsorption constant, heats of adsorption and entropy of adsorption have been estimated. In terms of the heat liberated on adsorption, the amino acids and a dipeptide can be ranked thus: aspartame > phenylalanine > aspartic acid > asparagine.

Adsorption↗

PubMedDate not supplied

Detection of creatinine enriched on a surface imprinted polystyrene film using FT-ATR-IR.

The surface of polystyrene (PS) was chemically modified by coating a thin layer of polyaniline (PANI) by oxidizing aniline using ammonium persulfate. Affinity sites for creatinine, a clinically relevant molecule, were created in the coated layer by adding creatinine as print molecules during the oxidation. The imprinted layer adsorbed creatinine was compared to non-imprinted surface reflecting the creation of creatinine-specific sites on the surface. The equilibrium was attained rapidly, indicating that a material of this kind is suitable for sensing applications. The adsorbed creatinine on the surface was detected using the technique of Fourier transform attenuated total internal reflection infra red spectroscopy (FT-ATR-IR). The results show that molecularly imprinted surface can enrich molecules of interest and the enriched molecules can be detected using FT-IR.

Adsorption↗

PubMed2003

Polystyrene derivatives substituted with arginine interact with Babanki (Togaviridae) and Kedougou (Flaviviridae) viruses.

Outbreaks of new or old diseases appear primarily in tropical zones such as Africa, south and central America, or Asia. Among these diseases, those induced by Arboviruses (the best known of which are being yellow fever, dengue, Ebola, and Sindbis) are under intensive observation by the World Health Organization. Rapid isolation and identification of the viral species is the first step in the diagnosis, study, and control of epidemics. One major problem with the isolation of viruses is capturing sufficient numbers of viral particles to test. The work presented in this report addresses this question. We have tested the interaction between Babanki (Togaviridae), Kedougou (Flaviviridae) viruses, and a range of insoluble polystyrene derivatives substituted with arginine groups. Insoluble functionalized copolymers were found to develop specific interactions with viruses through chemical groups present on their surfaces. The adsorption of viruses varied according to the percentage of arginine substituted onto the polymer, with a maximum value for both viruses of about 20% of grafting rate. It was also found that the Kedougou virus displayed the highest affinity for this polymer.

Adsorption↗

PubMed1989

[Loading of polystyrene solid phases with microbial agents and their polysaccharide antigens for the screening of monoclonal antibodies].

Before screening monoclonal antibodies using enzyme immuno assays, it is necessary to prove that the coating of the solid phases occurs efficiently. The adhesion of whole cells of group B streptococci, Escherichia coli K1, Haemophilus influenzae type b and Candida albicans as well as B-Streptococcus group antigen, H. influenzae type b capsular antigen, and C. albicans cell wall antigen to polystyrene solid phases was studied and detected by the following methods: Peroxidase competition procedure, scintillation measurement of 32phosphate-labelled germs, and reactions with monoclonal antibodies.

Antibodies, Monoclonal↗

PubMed1981

Acute hemodynamic effects and blood pool kinetics of polystyrene microspheres following intravenous administration.

The acute hemodynamic effect of intravenous administration of polystyrene microspheres was investigated and correlated with their distribution pattern and kinetics. Microspheres of three diameters (3.4, 7.4, and 11.6 micrometer) were administered. The 7.4- and 11.6-micrometer diameter microspheres were filtered by the pulmonary capillary network following intravenous administration, the majority during the first pass. There was no significant hemodynamic effect following administrations of the 7.4- and 11.6-micrometer diameter microspheres in doses as high as 3.0 X 10(9) and 6.1 X 10(8) respectively (total cross-sectional area of 1.3 X 10(11) and 6.4 X 10(10) micrometer2, respectively). Intravenous administration of 3.4-micrometer diameter microspheres produced significant dose-dependent systemic hypotension and depression of myocardial performance at dosages as slow as 1.0 X 10(10) (cross-sectional area of 9.1 X 10(10) micrometer2). These differences in acute hemodynamic effect from the 7.4- and 11.6-micrometer diameter microspheres may be due to the differences in distribution kinetics and fate of the 3.4-micrometer diameter microspheres, which readily pass through the lungs to the spleen. Although elimination of the smaller spheres from the blood during the first 6-8 min was rapid, i.e., t 1/2 = 1.62 and 1.72 min from the venous and arterial blood circulation, respectively, levels of 10(3) spheres/g of blood were present in the circulation for greater than 1 hr. These findings must be considered in the planning of intravenous administration of microspheres as a drug delivery system to target organs.

Animals↗

PubMed1983

Effect of the nonionic surfactant poloxamer 338 on the fate and deposition of polystyrene microspheres following intravenous administration.

The blood clearance and organ deposition of polystyrene microspheres in the rabbit following intravenous injection has been investigated using the technique of gamma scintigraphy, blood and organ level measurements, and histology. Uncoated microspheres of 1.27-microns diameter were cleared rapidly from the blood and were taken up primarily by the reticuloendothelial system in the liver. Coating of the microspheres with the nonionic surface-active agent poloxamer 338 reduced the uptake in the liver and gave a corresponding increase in the lungs.

Animals↗

PubMed1995

Circulation time and body distribution of 14C-labeled amino-modified polystyrene nanoparticles in mice.

Commercially available amino-modified polystyrene particles of size range 100-1,000 nm were radioactively labeled with [14C]-formaldehyde. A study of the circulation time and body distribution of these particles was carried out in mice. The animals were sacrificed at 1-30 min after intravenous administration of the particles. The blood and organ (liver, spleen, lung) profiles of particles were determined by measuring their radioactivity by means of liquid scintillation counting. In general, larger particles were eliminated from blood faster than smaller particles. The blood elimination half-life ranged from 1.36 to 4.92 min. The particles were mainly taken up by the liver with larger particles being taken up faster than the smaller particles. At 30 min after injection, 60% of the administered 100 nm particles were present in the liver, whereas 85% of the 100 nm particles were found in the liver. Accumulation in the spleen was 1-3% of the total number administered in the entire size range. At 1 min after injection, less than 3% of the total dose administered was present in the lungs and this value decreased rapidly to less than 1% at 2 min. The only exception occurred for 100 nm, where 2.35% was present in the lungs at 2 min after injection.

Animals↗

PubMed2004

Surface-grafted polystyrene beads with comb-like poly(ethylene glycol) chains: preparation and biological application.

We prepared surface-grafted polystyrene (PS) beads with comb-like poly(ethylene glycol) (PEG) chains. To accomplish this, conventional gel-type PS beads (35-75 microm) were treated with ozone gas to introduce hydroperoxide groups onto the surface. Using these hydroperoxide groups, poly(methyl methacrylate) (PMMA, Mn= 22,000-25,000) was grafted onto the surface of the PS beads. The ester groups of the grafted PMMA were reduced to hydroxyl groups with lithium aluminum hydride (LAH). After adding ethylene oxide (EO) to the hydroxyl groups, we obtained the PS-sg-PEG beads, which had a rugged surface and a diameter of 80-150 microm. We could obtain several kinds of the PS-sg-PEG beads by controlling the chain lengths of the grafted PMMA and the molecular weights of the PEG chains. The grafted PEG layer was about 30-50 microm thick, which was verified from the cross-sectioned views of the fluorescamine-labeled beads. These fluorescence images proved that the beads possessed a pellicular structure. Furthermore, we found that the surface-grafted PEG chains had the characteristic property of reducing non-specific protein adsorption on the beads.

Fluorescence↗

PubMed2001

Gel-Phase synthesis of hydrophobic (thr14) (thr19) galanin (1 -19) fragment on a high capacity flexible crosslinked polystyrene support.

A hydrophobic analogue of human galanin (1-19) fragment has been synthesized using Boc/Bzl tactics to demonstrate the synthetic utility of the flexible crosslinked polystyrene support prepared by the suspension polymerization of styrene and 1,4-butanediol dimethacrylate. The copolymer was chloromethylated to 2.36 mmol Cl/g. The functionalized resin was found to possess all the physicochemical properties similar to Merrifield resin. The free peptide was obtained in high yield and purity as judged by RP-HPLC and characterized by amino acid analysis and ESI-MS.

Chromatography, High Pressure Liquid↗