| 1. |
- Bender, Johanna, 1975, et al.
(författare)
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Structure and dynamics of a sponge phase in the methyl delta-aminolevulinate/monoolein/water/propylene glycol system
- 2008
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Ingår i: Journal of Colloid and Interface Science. - : Elsevier BV. - 1095-7103 .- 0021-9797. ; 17:2, s. 577-584
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Tidskriftsartikel (refereegranskat)abstract
- The structural effect caused by the addition of up to 16% (w/w) of the hydrochloride salt of delta-aminolevulinic acid (ALA, HOOC-CH(2)-CH(2)-CO-CH(2)-NH(2)HCl) or its methyl ester (m-ALA) to the sponge phase formed of monoolein/water/propylene glycol was investigated by means of crossed polarizers, small angle X-ray diffraction (SAXD) and nuclear magnetic resonance diffusometry (NMRD). Inspection with crossed polarizers revealed that additions of 4-16% (w/w) m-ALA transformed the isotropic bicontinuous sponge phase partly (4-10%) or completely (13 and 16%) into an anisotropic lamellar phase, indicating that m-ALA has a flattening effect on the bilayer curvature. The addition of 16% (w/w) ALA did not show any effect on the sponge phase. By addition of water to the anisotropic m-ALA samples, isotropic liquids were re-formed. The SAXD data for the isotropic liquids showed a diffuse Bragg peak and the NMRD self-diffusion coefficients for the drug (m-ALA) and the components of the original sponge phase (monoolein, water and propylene glycol) were shown to be essentially constant for 0-16% (w/w) added m-ALA. These results confirmed the hypothesis that the re-formed isotropic phases were indeed sponge phases. Water, for example, showed a diffusion coefficient of 3.1-3.9x10(-10)m(2)s(-1) in the sponge phase, compared to 5.3-5.7x10(-10)m(2)s(-1) in relevant water/propylene glycol solutions or 2.3x10(-9)m(2)s(-1) in pure water. The reduction can be explained as a consequence of the microstructure (congruent monoolein bilayer) of the sponge phase and of the viscosity effect caused by propylene glycol and m-ALA.
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| 2. |
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| 3. |
- Bergstrand, Anna, 1974, et al.
(författare)
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Comparison of PEI-PEG and PLL-PEG Copolymer Coatings on the Prevention of Protein Fouling
- 2009
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Ingår i: Journal of Biomedical Materials Research - Part A. - : Wiley. - 1552-4965 .- 1549-3296. ; 88:3, s. 608-615
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Tidskriftsartikel (refereegranskat)abstract
- The effect of surface charge on the protein resistance of adsorbed layers of poly(ethylene imine)-[g]poly(ethylene glycol), PEI-PEG, and poly(L-lysine)-[g]poly(ethylene glycol), PLL-PEG, was studied. Mixed and monofunctional self-assembled monolayers, SAMs, on gold were obtained by adsorption of 16-mercapto-1-hexadecanoic acid and 16-mercapto-1-hexadecanol. The surface charge was systematically varied by changing the ratio of the two alkanethiols. The graft copolymers PEI-PEG and PLL-PEG were adsorbed at the SAMs and tested for resistance towards human serum albumin and fibrinogen. The adsorbed amount of copolymers increased with increasing negative surface charge. However, the best protein resistance was found at an intermediate surface charge. The PLL-PEG covered Surfaces showed better protein resistance than the PEI-PEG covered surfaces. Thus, this work demonstrates that an adsorbed layer of PEG-grafted PEI and, in particular, PEG-grafted PLL is efficient in preventing protein adsorption when there is charge neutralization between the copolymer and the underlying surface.
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| 4. |
- Bergstrand, Anna, 1974, et al.
(författare)
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Towards a biosensor immunoassay of protein-bound isopeptides in human plasma
- 2008
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Ingår i: Colloids and Surfaces B: Biointerfaces. - 0927-7765 .- 1873-4367. ; 66, s. 150-
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Tidskriftsartikel (refereegranskat)abstract
- This study demonstrates that synthetic isopeptides formed on BSA can be quantitatively analyzed by a surface plasmon resonance-based biosensor method. A monoclonal IgM antibody 81D4, that reacts with the synthetic isopeptide and also with the natural isopeptide cross-link in D-dimer (but not with its non-cross-linked fibrin monomer), was covalently immobilized to a carboxymethylated dextran surface, a CM5 surface. Its immunocapturing efficiency was found to be good. The affinity of the interaction between the monoclonal 81D4 and the synthetic isopeptide was estimated to approximately 4x10(-7)M. Good reactivity was also observed when human plasma spiked with this isopeptide was used as test solution. Cross-linked D-dimer in the plasma of patients is a marker of disseminated intravascular coagulation (DIC) which occurs late in sepsis. This biosensor method has the potential to be developed into a rapid sensitive assay for measuring the level of natural isopeptide cross-links in proteins in the plasma of patients with a suspected diagnosis of sepsis.
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| 5. |
- Blanck, Hans, 1950, et al.
(författare)
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New strategy for design of optimised combinations of antifoulants: mixture efficacy predictions, risk weighting and microcapsule technology
- 2008
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Ingår i: 14th International Congress on Marine Corrosion and Fouling, July 2008, Kobe Japan.
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Konferensbidrag (refereegranskat)abstract
- Organisms differ in their sensitivity to toxicants, and each biocide will have its own efficacy profile. Whenever an antifoulant is used to affect organisms beyond its high-efficacy profile, an excess of biocides will be emitted to the environment. We propose an unprejudiced and rational design of efficacy-optimised combinations with minimum environmental risk. To control release of several antifoulants independently we use microcapsules bound to a polymer coating. The approach is based on three initial steps: Mixture toxicity concepts are used to predict efficacy of >100 000 combinations of 2-8 antifoulants. Predictions are based on full concentration-efficacy relationships with regard to prevention of settling of fouling model organisms (e.g. periphyton, sea lettuce, barnacles, sea squirt, blue mussel). Based on the predictions we will identify a set of > 100 000 combinations that are efficacious to all model organisms, and define their mixture concentrations and mixture ratios. Risk ratios (e.g. PEC/ PNEC) for the individual antifoulants are then used as weighing factors to rank the combinations according to their estimated relative risk to the environment. This results in a set of promising antifoulant combinations defined by their constituents, mixture ratios and total concentrations in water. The release rate from each of the individual mixture components will be regulated by microcapsule numbers, chemical and physical properties, to deliver the expected combination at the surface of the ship hull. The flexibility of the paint formulation ・with one antifoulant only in each capsule ・suggests that the coating can easily be reformulated to adjust to more demanding conditions. This study is a part of the Marine Paint Research Programme funded by MISTRA, the Foundation for Strategic Environmental Research, Sweden.
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| 6. |
- Boissier, Catherine, 1972, et al.
(författare)
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Interactions between polyvinylpyrrolidone, sodium dodecylsulfate and nonylphenol ethoxylate in solution and on polystyrene particles
- 2007
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Ingår i: Colloids and Surfaces A: Physicochemical and Engineering Aspects. - : Elsevier BV. - 1873-4359 .- 0927-7757. ; 301:1-3, s. 444-452
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Tidskriftsartikel (refereegranskat)abstract
- Mixtures of polyvinylpyrrolidone (PVP), nonylphenol ethoxylate with, on the average, 84 oxyethylene units (NP 100) and sodium dodecylsulfate (SDS) in solution and on polystyrene particles are discussed in terms of various types of interaction according to their mutual affinities. The mixtures in solution were analyzed by means of NMR and static surface tension, which showed that the combination of SDS with PVP agreed well with the classical model with surfactant aggregates along the polymer chain. In the mixture with the nonionic surfactant NP100 and the anionic surfactant SDS, mixed micelles were formed with a strong attraction parameter beta = -5. 1. Evidence of SDS encapsulation in the NP100 micelle was obtained from NMR diffusometry data where the long and short residence times of SDS in the mixed micelle were estimated to be iota(A) = 2.19 s and TB = 0. 15 s, respectively. No interaction was found in a mixture between NP100 and PVP in solution. Upon adsorption of these component mixtures to a polystyrene surface, it was shown that complexes formed in solution also dominated at the surface. This applied both for the mixtures of SDS-PVP and of SDS-NP100, with the exception that the mixed micelles of SDS-NP100 seemed to have higher affinity than PVP to the surface. This was considered a result of the nonylphenol group in NP100. For the mixture of NP100 and PVP, the NP100 had a higher affinity to the surface than PVP, though both components were able to co-exist on the surface. Finally, as SDS, NP100 and PVP were adsorbed simultaneously, all three components seemed to adsorb, with a surface complex including SDS with, probably, both NP100 and PVP. In this three-component mixture a preferential adsorption of SDS and NP100 seemed to exist.
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| 7. |
- Boissier, Catherine, 1972, et al.
(författare)
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Water-based latex dispersions: 4. Exchange dynamics and residence times of nonylphenol ethoxylate in concentrated latex dispersions
- 2005
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Ingår i: Journal of Colloid and Interface Science. - : Elsevier BV. - 1095-7103 .- 0021-9797. ; 292:1, s. 63-70
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Tidskriftsartikel (refereegranskat)abstract
- The equilibrium residence times of the nonionic surfactant nonylphenol ethoxylate (NP100) in a latex dispersion were determined using NMR diffusometry. At 16% w/w particle concentration and 0.12, 0.43 and 0.81% w/w NP100, the residence times of the surfactant were 0.16, 1.02 and 4.73 s in solution (τA) and 0.3, 0.37 and 0.61 s on the surface of the particles (τB), respectively. At even higher particle concentration (>45% w/w), τA and τB were 1.47 and 2.2 s. Calculating the number of collisions that ought to result in adsorbed species, at 16% w/w, only 2, 5 and 2‰ (corresponding to 0.12, 0.43 and 0.81% w/w NP100) resulted in adsorption, whereas at >45% w/w, only 12‰ resulted in adsorption, which suggested that the surfactant was irreversibly adsorbed on the particles. The small increase in collision frequency with increased particle concentration could be a result of a diffusion controlled adsorption, while an energy barrier for desorption controlled the overall exchange dynamics in the dispersion. The slow dynamics in the dispersion was controlled, mainly by the nonylphenol group, which gave NP100 a strong preference to surfaces. In addition, the chain length of the poly(ethylene glycol) (PEG) group changed the solution behavior from being that of a typical surfactant to that of a polymer.
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| 8. |
- Boissier, Catherine, 1972, et al.
(författare)
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Water-Based Latex Dispersions. 5: NMR Relaxation Studies of Deuterium Labeled Nonylphenol Ethoxylate
- 2009
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Ingår i: Journal of Dispersion Science and Technology. - : Informa UK Limited. - 1532-2351 .- 0193-2691. ; 30:6, s. 873-880
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Tidskriftsartikel (refereegranskat)abstract
- The dynamics and conformation of the nonionic surfactant NP100 (nonylphenol ethoxylate with an average of 84 oxyethylene units), adsorbed on colloidal silica and on polystyrene latex particles, have been studied by the nuclear magnetic resonance relaxation technique. To obtain specific information about the spin relaxation from the methylene groups situated at the hydroxyl-terminal end of the polyoxyethylene (POE) chain, this part was labeled with deuterium in a two-step synthesis. Spin relaxation studies of the labeled part of the adsorbed surfactant (2H relaxation) suggested that the dynamics was slower in comparison with the spin relaxation of the surfactant in solution. Also, it was seen that the dynamics was slower on the silica surface than on the polystyrene surface. This was in agreement with previous studies on the average proton spin relaxation of the whole POE chain of the surfactant on silica and on polystyrene surfaces. The correlation time constant for the slow motions of the POE chain was calculated to be as large as 7.4 ms for NP100 on the polystyrene particles. Also this was in good agreement with studies made on the exchange dynamics of the surfactant in different dispersions, where it was found that the exchange between the solution and the particles was slow.
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| 9. |
- Brown, J. R., et al.
(författare)
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Dynamics of the solid and liquid phases in dilute sheared Brownian suspensions: Irreversibility and particle migration
- 2007
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Ingår i: Physical Review Letters. - 1079-7114 .- 0031-9007. ; 99:24, s. 4-
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Tidskriftsartikel (refereegranskat)abstract
- Magnetic resonance measurements of migration and irreversible dynamics in the capillary shear flow of a Brownian suspension are presented. The results demonstrate the presence of phenomena typically associated with concentrated noncolloidal systems and indicate the role of many body hydrodynamics in dilute Brownian suspension transport. The application of concepts from chaos theory and nonequilibrium statistical mechanics is demonstrated.
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| 10. |
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