共查询到4条相似文献,搜索用时 15 毫秒
1.
O. López M. Cócera L. Coderch J. L. Parra A. de la Maza 《Colloid and polymer science》2002,280(4):352-357
The lytic interactions of the nonionic surfactant dodecyl maltoside (DM) with liposomes formed by a mixture of lipids modeling
the stratum corneum (SC) lipid composition were investigated. To this end, the surfactant to lipid molar ratios (Re) and the
normalized bilayer/aqueous phase partition coefficients (K) were determined by monitoring the changes in the static light-scattering
(SLS) of the system during solubilization. The fact that the free surfactant concentration was always similar to its critical
micelle concentration indicates that the liposome solubilization was mainly ruled by formation of mixed micelles. In addition,
the linear dependence established between the level of SLS and Re indicates a progressive incorporation of DM in the liposomes
as well as the progressive formation of mixed micelles. DM showed in all cases lower bilayer activity (higher Re values) and
greater affinity with vesicles (higher K values) than those reported for its interaction with phosphatidylcholine (PC) liposomes.
Thus, whereas the SC lipid liposomes were more resistant to the action of this surfactant, its degree of partitioning into
SC bilayers was higher throughout the solubilization process than that exhibited in PC vesicles. Comparison of the present
Re values with those reported for the lytic interaction of dodecyl glucoside (DG) with SC liposomes reveals that in the case
of DM the bilayer activity was more than three times higher than that for DG in spite of the identical alkyl chain length.
Received: 19 July 2001 Accepted: 10 October 2001 相似文献
2.
The interaction of a series of polyethoxylated octylphenols (ethylene oxide units average 8.5–20.0) with liposomes modeling
the stratum corneum (SC) lipid composition (40% ceramides, 25% cholesterol, 25% palmitic acid and 10% of cholesteryl sulfate)
was investigated. The surfactant/lipid molar ratios (Re) and the bilayer/aqueous-phase partition coefficients (K) were determined by monitoring the changes in the static light scattering of the system during solubilization. The fact that
free concentration for each surfactant tested was always similar to its critical micelle concentration (CMC) indi-cates that
the liposome solubilization was mainly ruled by the formation of mixed micelles. The Re and K para-meters for liposome saturation fell as the surfactant HLB increased. Thus, at this interaction step the higher the surfactant
HLB, the higher the ability of these surfactants to saturate SC liposomes and the lower their degree of partitioning into
liposomes. However, the maximum solubilizing ability was achieved at intermediate HLB values. Thus, the octylphenols with
20 and 12.5 ethylene oxide units showed, respectively, the highest power of saturation and solubilization of SC structures
in terms of the total surfactant amounts needed to produce these effects. Different trends in the interaction of these surfactants
with SC liposomes were observed when comparing the Re and K parameters with those reported for PC ones. Thus, whereas the SC liposomes were more resistant to the surfactant action,
the affinity of these surfactants with these bilayer structures was higher in all cases.
Received: 3 March 1997 Accepted: 22 May 1997 相似文献
3.
M. Cócera O. López L. Coderch J. L. Parra A. de la Maza 《Colloid and polymer science》2000,278(8):794-799
The role played by cholesteryl sulfate (Chol-sulf) in the solubilization of liposomes modeling the stratum corneum (SC) lipids
by sodium dodecyl sulfate (SDS) was studied. We determined the surfactant-to-lipid molar ratios and the bilayer/aqueous phase
surfactant partition coefficients of this interaction by varying the proportion of Chol-sulf, the relative proportions of
the others lipids remaining constant. These parameters were determined by monitoring the changes in the static light scattering
of the system during solubilization. The fact that the free surfactant concentration was always similar to its critical micelle
concentration indicates that the liposome solubilization was mainly ruled by the formation of mixed micelles. The SDS ability
to saturate and solubilize SC liposomes decreased as the proportion of Chol-sulf in the bilayers increased until a minimum
was reached for a Chol-sulf proportion of about 15%. Inversely, the SDS partitioning into liposomes (or affinity with these
bilayers) increased as the proportion of Chol-sulf increased until a maximum was reached at similar Chol-sulf proportions
(10–15%). Hence, in these Chol-sulf proportions (similar to that existing in the intercellular lipids, which was 10%) the
ability of SDS molecules to interact with liposomes exhibits a minimum despite their enhanced partitioning into liposomes.
These effects may be related to the reported dependencies of the level of Chol-sulf on the abnormalities in the skin barrier
function and on the SC intercellular cohesion.
Received: 12 October 1999 Accepted: 20 January 2000 相似文献
4.
Renate Lieckfeldt Jos Villalaí n Juan-Carmelo G mez-Fern ndez Geoffrey Lee 《Colloids and surfaces. A, Physicochemical and engineering aspects》1994,90(2-3):225-234
The phase behaviour of a hydrated (32% (w/w) water) mixture of saturated and unsaturated fatty acids and their soaps has been examined. By progressively increasing the proportion of oleic acid, it could be shown that this unsaturated component exists partly as a separate phase within the others. The unsaturated fatty acids form an HII phase at 25°C, whereas the saturated fatty acids form a fatty acid—soap crystal under the conditions employed. The results help to explain the role played by the fatty acids (and also cholesterol) within the lipid fraction of human stratum corneum. A feature of this study is a comparison of the results obtained by X-ray diffraction, differential scanning calorimetry and Fourier transform infrared spectroscopy. 相似文献