| 1. |
- Muller, D, et al.
(författare)
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Competitive adsorption of gelatin and sodium dodecylbenzenesulfonate at hydrophobic surfaces
- 1998
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Ingår i: Langmuir. - 0743-7463 .- 1520-5827. ; 14, s. 3107-3114
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Tidskriftsartikel (refereegranskat)abstract
- The competitive adsorption of gelatin and sodium dodecylbenzenesulfonate (SDBS) at hydrophobic surfaces was investigated with surface and interfacial tension measurements, ellipsometry, surface plasmon resonance spectroscopy (SPR), and total internal reflectance fluorescence spectroscopy (TIRF). From both ellipsometry and SPR, initial additions of SDBS after gelatin preadsorption were found to result in a total adsorbed amount increase, as well as in a swelling of the adsorbed layer. At higher SDBS concentrations, both the total adsorbed amount and the amount of gelatin adsorbed decrease, which was observed from ellipsometry, SPR, and TIRF. From surface and interfacial tension measurements, it was found that the critical aggregation concentration (cac) for the SDBS-gelatin system decreases with decreasing pH. Analogous to this, ellipsometry, SPR, and TIRF indicate that the SDBS concentration required to cause a significant decrease in the gelatin adsorbed amount decreases with decreasing pH. The desorption therefore seems to be correlated to the SDBS binding to the adsorbed gelatin molecules rather than to purely competitive adsorption.
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| 2. |
- Muller, D, et al.
(författare)
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Interaction of gelatin and sodium dodecyl benzene sulphonate at oil and water interfaces
- 1997
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Ingår i: Imaging Science Journal. - 1368-2199 .- 1743-131X. ; 45, s. 229-235
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Tidskriftsartikel (refereegranskat)abstract
- Interaction between sodium dodecyl benzene sulphonate (SDBS) and gelatin was studied in relation to emulsification behaviour and emulsion stability. We chose two different oils to study influences of oil phase characteristics, namely, tricresyl phosphate (TCP) as an oil with polar and slightly hydrophilic nature, and n-docedane (nC12) as its apolar contrast. Our interfacial tension measurements showed that both TCP and n-C12 give critical values (i.e., cac and cmc) very close to those of surface tension measurement. This result indicates that the complexation behaviour in bulk solution is independent of the presence or the nature of the oil phase. Absolute tension values above the cmc and slope values at the cmc in gelatin free systems, however, imply SDBC's weaker adsorption to TCP than to n-C12. Our emulsification results for the TCP system revealed the existence of an optiomal point for emulsion stability in the SDBS concentration region between the cac and the cmc. Above this point, emulsion stability deteriorates remarkably. The behaviour is in line with our findings from the dynamic sorption expriments (ellipsometry, TIRF, and SPR) reported elsewhere, which showed a rapid desorption of gelatin from the hydrophobic surfaces above the cac. The results suggest that the adsorption of gelatin/ surfactant complexes at the interface is a key factor for stability of the polar oil emulsion system. Contrary to that , the n-c12 system did not show any deterioration, even above the cmc, which is presumably due to a strong double layer effect from the firmly adsorbed layer of SDBS at the interface.
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| 3. |
- Bartholeyns, J, et al.
(författare)
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Cellular vaccines
- 1998
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Ingår i: Research in Immunology. - 0923-2494 .- 1879-1425. ; 149, s. 647-649
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Tidskriftsartikel (refereegranskat)abstract
- This project is devoted to the development of novel cellular vaccines designed to treat cancer patients. These cellular vaccines present and enhance immunogens, which will elicit a potent immune response. The goal is to achieve safe and effective immune reaction against the patient's own tumour. (1) Autologous cellular vaccines are prepared by processing circulating brood mononuclear cells outside of the patient's body (ex vivo) to differentiate them into antigen-presenting cells (APCs). Monocyte-derived APCs (MD-APCs) are then grown in the presence of exogenous target antigens (tumour cell debris, or apoptotic bodies) to become fully mature APCs. (2) Functionality for antigen presentation to T cells of ex vivo MD-APCs is evaluated in vivo. (3) Cellular vaccines are tested in selected rodent animal models. Efficiency and immune response are monitored in pertinent experimental systems for cancer. Pharmacological data are generated for clinical investigation. Tolerance and biologic effects are documented in primates. (4) The first clinical trials on cancer patients are taking place in 1998 on melanoma and prostate cancer to validate the concept. Specialized eel processors with dedicated software and standardized controls are being developed and used for the preparation of cellular vaccines. (5) The evaluation of new non-viral vectors and the validation of new non-viral transfection methods of mononuclear cells with marker genes is in progress and will lead to the ex vivo transfection of genes coding for immunostimulating cytokines or for tumour antigens in MD-APCs. Efficiency will be validated in vitro and in animal models. The ex vivo and animal model studies validate the clinical relevance of this new cellular immunotechnology. Clinical validation of individual autologous cellular vaccines in specific indications for which no treatment is presently available will allow the development of cellular and gene immunotherapy for other types of cancers.
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| 4. |
- Griffiths, PC, et al.
(författare)
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Role of copolymer architecture on adsorption at the solid/liquid interface
- 1998
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Ingår i: Langmuir. - 0743-7463 .- 1520-5827. ; 14, s. 1779-1785
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Tidskriftsartikel (refereegranskat)abstract
- The adsorption of monodisperse block copolymers comprising poly(ethylene oxide)-poly(butylene oxide) onto polystyrene latex from aqueous solution has been investigated by small-angle neutron scattering and photon correlation spectroscopy with particular reference to the role of molecular architecture. It appears that chain architecture is (i) a weak factor in the adsorption behavior when the hydrophobic block is located in the center of the polymer, since the triblock E100B15E100 behaved very similarly to the cyclic c-E200B15, but (ii) a significant factor when the hydrophobic block is located at the end of the copolymer chain, as shown by the more dense and thicker layer formed by E200B15 compared to the triblock E100B15E100. The hydrodynamic thickness of the layer formed by the small diblock E100B15 was approximately half that exhibited by the larger diblock E200B15. Good agreement was observed between depletion and SANS-derived adsorbed amounts. Theoretical predictions and self-consistent mean-field calculations of the adsorption also show excellent qualitative agreement with experiment.
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| 5. |
- Malmsten, M, et al.
(författare)
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Adsorption of complement protein C3 at polymer surfaces
- 1996
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Ingår i: Journal of Colloid and Interface Science. - 0021-9797 .- 1095-7103. ; 179, s. 163-172
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Tidskriftsartikel (refereegranskat)abstract
- The adsorption of C3 at poly(methyl methacrylate) (PMMA) and poly(styrene) (PS) surfaces was investigated with in situ ellipsometry and compared to that at (hydrophilic and negatively charged) silica and (hydrophobic) methylated silica. The adsorption of C3 at PMMA was higher than that at PS, while the adsorbed layer thickness was the same for the two surfaces. For both PMMA and PS the adsorbed layer thickness (10±2 nm) corresponds rather closely to that of end-on oriented C3 molecules. The adsorption of C3 at PMMA and PS was found to be intermediate between that at silica and methylated silica, although the adsorbed layer thickness was similar for all surfaces. The competitive adsorption between C3, human serum albumin (HSA), and factor B was investigated with ellipsometry and total internal reflection fluorescence spectroscopy (TIRF). Addition of HSA after C3 preadsorption resulted in fractional C3 desorption for both PMMA and PS. Factor B deposition at PS after preadsorption of C3 and blocking with HSA was found to be largely due to specific binding to C3/C3b, while in the case of PMMA, factor B was largely accumulated through passive (displacement) adsorption.
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| 6. |
- Malmsten, M, et al.
(författare)
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Protein adsorption at n-butane plasma polymer surfaces
- 1996
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Ingår i: Colloids and Surfaces B. - 0927-7765 .- 1873-4367. ; 6, s. 191-199
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Tidskriftsartikel (refereegranskat)abstract
- The adsorption of human serum albumin (HSA) and fibrinogen at n-butane plasma polymer surfaces prepared by low temperature plasma polymerization at different energy inputs have been investigated with in situ ellipsometry. Within experimental uncertainty, the adsorption of both fibrinogen and HSA is constant over the power range used for the preparation of the n-butane surfaces and corresponds to that found for other hydrophobic surfaces at similar conditions. Furthermore, novel copolymer surfaces of n-butane and nitrogen at different ratios were prepared and investigated. Increasing the nitrogen content in the gas mixture during deposition resulted in an increased density of interfacial amine groups, as evidenced by an increased wettability, an increased interfacial nitrogen content, and an increased surface positive charge. This, in turn, was found to result in an increased fibrinogen adsorption, but in a weak decrease in the HSA adsorption.
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