| 1. |
- Balogh, Joakim, et al.
(författare)
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Investigating the Effect of Adding Drug (Lidocaine) to a Drug Delivery System Using Small-Angle X-Ray Scattering
- 2008
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Ingår i: Colloids for Nano- and Biotechnology (Progress in Colloid and Polymer Science). - Berlin, Heidelberg : Springer Berlin Heidelberg. - 0340-255X. - 9783540851332 ; 135, s. 101-106
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Konferensbidrag (refereegranskat)abstract
- The effect on a model drug delivery system when adding a drug, lidocaine, has been studied. Temperature and concentration dependence of a nonionic microemulsion with part of the oil, 1 and 10 vol. %, substituted with drug has been investigated. A nonionic oil-in-water microemulsion consisting of CH3(CH2)(11)(OCH2CH2)(5)OH, (C12E5), decane, water and the drug (lidocaine) that has been used to substitute part of the oil was studied. The microscopic differences have been derived from small-angle X-ray scattering (SAXS) data and the results are compared with light scattering data. Using these results together with the macroscopic differences, as observed in the phase diagram (lowering of phase boundaries), between the systems with and without lidocaine can be explained.
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| 2. |
- Costa, Fatima, et al.
(författare)
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Drug Release and Skin Permeation from Lipid Liquid Crystalline Phases
- 2008
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Ingår i: Colloids for Nano- and Biotechnology (Progress in Colloid and Polymer Science). - Berlin, Heidelberg : Springer Berlin Heidelberg. - 0340-255X. - 9783540851332 ; 135, s. 119-129
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Konferensbidrag (refereegranskat)abstract
- We have studied drug release and skin permeation from several different liquid crystalline lipid formulations that may be used to control the respective release rates. We have studied the release and permeation through human skin of a water-soluble and amphiphilic drug, propranolol hydrochloride, from several formulations prepared with monoolein and phytantriol as permeation enhancers and controlled release excipients. Diolein and cineol were added to selected formulations. We observed that viscosity decreases with drug load, wich is compatible with the occurrence of phase changes. Diolein stabilizes the bicontinuous cubic phases leading to an increase in viscosity and sustained release of the drug. The slowest release was found for the cubic phases with higher viscosity. Studies on skin permeation showed that these latter formulations also presented lower permeability than the less viscous monoolein lamellar phases. Formulations containing cineol originated higher permeability with higher enhancement ratios. Thus, the various formulations are adapted to different circumstances and delivery routes. While a slow release is usually desired for drug sustained delivery, the transdermal route may require a faster release. Lamellar phases, which are less viscous, are more adapted to transdermal applications. Thus, systems involving lamellar phases of monoolein and cineol are good candidates to be used as skin permeation enhancers for propranolol hydrochloride.
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| 3. |
- Gonzalez Perez, Alfredo, et al.
(författare)
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Temperature Induced DNA Compaction in a Nonionic Lamellar Phase
- 2008
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Ingår i: Colloids for Nano- and Biotechnology (Progress in Colloid and Polymer Science). - Berlin, Heidelberg : Springer Berlin Heidelberg. - 0340-255X. - 9783540851332 ; 135, s. 174-180
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Konferensbidrag (refereegranskat)abstract
- A nonionic lamellar phase was prepared using C10E3 in buffer solution at pH = 7.6. A suitable T4DNA concentration around 5 wt % was immobilized in a lamellar phase with 40 wt % C10E3. The mixed system was investigated at two temperatures, 25 and 5 degrees C by using cryo-fracture TEM direct imaging, fluorescence microscopy and small-angle X-ray scattering. The surprising results where obtained showing that the DNA conformation can be tuned to compacted and extended state at 25 and 5 degrees C, respectively. Additionally, DNA is aligned with a preferential orientation in the direction of the flow by simply injecting the sample in a capillary.
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| 4. |
- Backlund, S, et al.
(författare)
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Partial phase behavior of ionic microemulsions stabilized by sodium dodecylsulfate and alcohol cosurfactants
- 1992
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Ingår i: Progress in Colloid and Polymer Science. - 0340-255X .- 1437-8027. ; 88, s. 36-41
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Tidskriftsartikel (refereegranskat)abstract
- Ionic microemulsions, stabilized by sodium dodecylsulfate and alcohol cosurfactants, have been characterized with respect to phase behavior, particularly the composition of the different phases in Winsor type I, II and III systems. The system containing brine, octane, sodium dodecylsulfate and 1-butanol shows a regular phase behavior, in conformity with the anticipated behavior, i.e., 2-3-2 phases. The phase transitions with increasing 1-butanol concentration are analogous to those occurring with increasing salinity, when compared with previous investigations. For the system containing brine, cyclohexane, sodium dodecylsulfate and benzyl alcohol, the behavior becomes more complex, even at low surfactant contents. The transitions are 2-3-2-3-2 phases over a wide composition range. The compositions of the phases at equilibrium are discussed in relation to structural considerations, as determined by conductivity and NMR self-diffusion measurements.
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| 5. |
- Backlund, S, et al.
(författare)
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Partical phase equilibria and partition of alcohol cosurfactants in ionic microemulsions
- 1990
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Ingår i: Progress in Colloid and Polymer Science. - 0340-255X .- 1437-8027. ; 82, s. 290-295
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Tidskriftsartikel (refereegranskat)abstract
- The partial phase behaviour of quintinary microemulsions containing water (0.5 m NaCl), sodium dodecylfate, octane and alcohol, where the alcohol is a butanol or pentanol isomer, has been determined. In addition, the partition of the cosurfactant between the phases has been investigated, as well as in detail for the 1-butanol system. The efficiency of the cosurfactant for forming microemulsions is found to exhibit no simple relationship to its solubility properties. In addition, while branched alcohol cosurfactants promote the formation of solution phases at high surfactant contents.
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| 6. |
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| 7. |
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| 8. |
- Bergström, Lars Magnus, et al.
(författare)
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Synergistic effects in binary surfactant mixtures
- 2004
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Ingår i: Progress in Colloid and Polymer Science. - Berlin, Heidelberg : Springer Berlin Heidelberg. - 0340-255X .- 1437-8027. ; 123, s. 16-22
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Tidskriftsartikel (refereegranskat)abstract
- By considering the main contributions to the micellar free energy we have analysed the synergistic effect often seen on the CMC of a binary surfactant mixture. The synergistic effects are due mainly to the entropic free energy contributions related with the surfactant head groups. Several cases have been treated: (i) For a mixture of a monovalent ionic and a non-ionic surfactant in the absence of added salt we obtain, entirely because of electrostatic reasons, a negative deviation from the ideal behaviour corresponding to an interaction parameter β≈-1. Upon adding an inert salt we found that the magnitude of the synergistic effect first increases, reaches a maximum and eventually decreases. (ii) For mixtures of two ionic surfactants with the same charge number but with different hydrocarbon moieties β-values as low as -10 may arise. (iii) For mixtures of an anionic and a cationic surfactant enormous effects are anticipated yielding β≤-20 depending on the CMCs of respective pure surfactant. (iv) Synergistic effects due to different cross-section areas of the head groups are found to be rather small, with 0 > β > -1, provided the difference in head group size is modest but can become more significant when the size difference is larger.
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| 9. |
- Billsten, P, et al.
(författare)
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Adsorption of human carbonic anhydrase II onto silicon oxides surfaces : The effects of truncation in the N-terminal region
- 1998
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Ingår i: The Colloid Science of Lipids New Paradigms for Self-Assembly in Science and Technology. - 1435-1536 .- 0340-255X. - 9783798511125 - 9783798516557 ; 108, s. 161-165
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Konferensbidrag (refereegranskat)abstract
- The adsorption of human carbonic anhydrase II pseudo-wild type (HCAIIpwt) and an N-terminally truncated version thereof onto silica surfaces were studied. The amount adsorbed and the adsorption kinetics were measured using in situ ellipsometry. A substantial difference was seen between the two proteins. The adsorbed amount of the truncated version (2.53 mg/m2) indicates an end-on orientation, while the HCAIIpwt seems to adsorb side-on (1.84 mg/m2). It is suggested that the orientation effects arise from the truncation. The truncation is known to unfold the two most N-terminal helical segments, which could inhibit adsorption with the N-terminal region facing the surface, due to steric repulsion.
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| 10. |
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