The action of Triton X-100 and sodium dodecyl sulphate on lipid layers. Effect on monolayers and liposomes

Abstract

The action of two detergents, Triton X-l 00 and sodium dodecyl sulphate (SDS), on large, unilamellar liposomes was determined as liposome size variation, polydispersity and ability to release a soluble marker from liposomes. Triton X-100 produced stronger effects than SDS. Nevertheless, these differences in behaviour of such detergents could not be deduced from the interaction of the detergents with monolayers of the same composition as liposomes.     

Interaction of opiate molecules with lipid monolayers and liposomes.

The interaction of opiate molecules (buprenorphine, codeine, dextromethorphan, diprenorphine, etorphine, meperidine, methadone, morphine, and naloxone) with lipids (phosphatidylcholine, phosphatidylinositol, phatidylinositol, phosphatidylserine, and cholesterol) by using liposomes and monomolecular layers as membrane models is described. The ability of opiates to induce leakage of carboxyfluorescin from liposomes is highly dependent on the hydrophobicity of the opiate molecules. Buprenorphine and etorphine increased the membrane permeability in all the experiments. On the contrary, naloxone, morphine, and codeine only caused a slight release of the entrapped dye in the presence of acidic phospholipids. Moreover, the leakage of carboxyfluorescein is directly related to the concentration of drug in the incubation media. Studies of the kinetics of the surface penetration of these molecules into monolayers of phospholipids were performed. Again, in this system, buprenorphine and etorphine exhibited stronger interactions than the most hydrophilic opiates. Nevertheless, in these experiments, differences among the opiate molecules are not so high as in the liposomes. The time course of the penetration of all of these molecules in the monolayers fits the Lineweaver-Burk equation. This fact suggests a lack of specific interactions and the predominance of hydrophobic factors. Moreover, the high percentage of release of entrapped dye caused by some opiate molecules suggests a possible toxic side-effect for these agents.     

Effects of Triton X-100 nanoaggregates on dimerization and antioxidant activity of morin

Dimerization and antioxidant activity of morin in the Triton X-100 micelles were studied by electronic absorption, ATR-FTIR spectra, cyclic voltammetric, DSC, freeze-fracture TEM, molecular modeling and ab initio quantum calculations. Morin can be solubilized in the Triton X-100 micelles and show selective dimerization in Triton X-100 micelles with different structures. In Triton X-100 spherical micelles, morin always exists in the form of dimer, and in Triton X-100 rodlike micelles, it is always in the form of monomer. The solubilization of morin dimer in Triton X-100 spherical micelles changes the micelle morphology from spherical to cubelike, and the size of the single micelle is also increased, while morin monomer links the Triton X-100 rodlike micelles and forms a kind of network micelle structure with the size of the "rod" unchanged. Solubilized and concentrated in Triton X-100 micelles, morin can protect human serum albumin from the damage induced by hydroxyl radicals effectively and even can form a kind of protein complex with human serum albumin showing more thermal stability.     

The influence of 1-hexadecanol on the acid-catalysed hydrolysis of sodium dodecyl sulphate

The kinetics at 60° of the acid-catalysed hydrolysis of sodium dodecyl sulphate in the presence of 1-hexadecanol above the critical micelle concentration showed the hydrolysis to be first order and the rate to depend on the molar ratio of alcohol to alkyl sulphate. Up to a ratio of 0.75 the rate increases; above this there is a steady decrease. The changes in rate have been correlated with phase changes and explained on the basis of the effect on the charge density on the micelle, and on the dielectric constant of the associated medium, in passing from a mixed spherical micelle to the lamellar structure and then to the expanded lamellar structure prevailing in liquid crystals.     

头孢唑酮在Triton X-100体系中的释放机制初探

目的 探讨抗生素药物头孢唑酮在表面活性剂体系中的释放机制.方法 测定了头孢唑酮在表面活性剂体系中的释放曲线,用数学模型对药物的释放曲线进行拟合.结果 头孢唑酮在TritonX,100体系的释放为非菲克扩散控制过程.结论 为表面活性剂体系中药物控制释放的深入研究提供了科学依据.     

Studies of monoamine oxidases: Effect of Triton X-100 and bile salts on monoamine oxidase in brain mitochondria

Triton X-100 and the bile salts, cholate and deoxycholate, detergents often used in the solubilization of monoamine oxidase (MAO) from mitochondria, have been found to cause an inhibition of the enzyme activity. With beef brain mitochondria, it was found that there was a differential effect of Triton X-100 on the putative MAO types A and B, with MAO-A being more susceptible to inhibition by Triton X-100. This was indicated by the greater loss of serotonin-deaminating than of phenyl ethylamine-deaminating activity in the presence of Triton X-100. Although the bile salts also caused substantial inactivation at concentrations above 0.1%, no differentiation between MAO types could be made. Kinetic studies of the inhibition by Triton X-100 indicated two different mechanisms were occurring with the two MAO types. The inhibition was competitive for MAO-A, but uncompetitive for MAO-B. Removal of Triton X-100 by co-polymer beads restored some, but not all of the activity for both MAO-A and MAO-B types. This suggests that the activity loss may have been due in part to inactivation when the enzyme was separated from the mitochondrial membrane.     

Interactions of rat brain acetylcholinesterase with the detergent Triton X-100 and the organophosphate paraoxon.

Inhibition of the critical enzyme acetylcholinesterase (E.C. 3.1.1.7) with subsequent cholinergic crisis is the mechanism of acute toxicity of the organophosphorus insecticides (B. E. Mileson et al., 1998, Toxicol. Sci.41, 8-20). Consequently, measurement of acetylcholinesterase activity is important for evaluating the mammalian toxicity of this commonly used class of insecticides. While mammalian acetylcholinesterase activity has often been determined in tissue homogenates in the presence of the nondenaturing detergent Triton X-100 at a concentration of 1%, the potential actions of this detergent on the activity of this critical enzyme are not understood. In the current study, homogenization of rat brain in buffer containing 1% Triton X-100 slightly elevated the (app)V(max) for hydrolysis of acetylthiocholine, without affecting the (app)K(m) or the (app)K(ss). However, the presence of both 1% Triton X-100 and paraoxon (at concentrations of 5 nM-100 nM) resulted in complex kinetic interactions with acetylcholinesterase, as evidenced by a curvilinear secondary plot for determination of the (app)k(i). These results suggest that measurement of acetylcholinesterase activity in the presence of up to 1% Triton X-100, but in the absence of oxon, should pose no problems with regard to data interpretation, provided it is recognized that the detergent slightly elevates activity. However, measurement of acetylcholinesterase activity after enzyme was exposed simultaneously to Triton X-100 and oxon could be problematic. Caution is warranted when interpreting data where acetylcholinesterase activity was determined under such conditions since in the presence of 1% Triton X-100, the capacity of oxon to inhibit acetylcholinesterase might change as a function of oxon levels.     

Combined antioxidant effects of rutin and vitamin C in Triton X-100 micelles

UV-vis spectra, fluorescence emission spectra and cyclic voltammetric measurements were used to study the influence of Vitamin C on the antioxidant of rutin in Triton X-100 micelles. Rutin can be located in Triton X-100 micelles spontaneously through hydrophobic force, and the binding constant K between rutin and Triton X-100 increases with the rutin concentration. The embedment of two hydroxyl groups on rutin into the more hydrophobic micellar microenvironment makes the oxidation of rutin harder and the radical scavenging activity decrease. With low concentration of Vitamin C, the antioxidant capacity of rutin against hydroxyl radical is enhanced, while that capacity is partly inhibited when the concentration of Vitamin C become higher.     

头孢唑酮在Triton X-100体系囊泡中的包封和缓释

目的研究了β-内酰胺类抗生素药物头孢唑酮在表面活性剂囊泡中的包封和释放行为。方法超声Triton X-100体系层状液晶制备了囊泡,用超离心分离法和紫外分光光度法测定头孢唑酮的包封率和释放速率。结果Triton X-100/n-C10H21OH/H2O体系囊泡对头孢唑酮具有较好的包封和缓释作用。结论表面活性剂体系囊泡可作为一种新的药物控制释放系统。     

Effects on the reproductive organs of feeding the non-ionic surfactant Triton X-100 to mice

A series of feeding experiments has shown Triton X-100 to induce cystic degeneration in the mouse ovary. Parallel experiments in ovariectomized mice revealed no evidence that Triton X-100 possesses oestrogenic activity. Long term exposure of female mice to this surfactant did not impair fertility.     

Morphological and physiological changes in Tetrahymena pyriformis for the in vitro cytotoxicity assessment of Triton X-100.

Non-ionic surfactants such as Triton X-100 have been widely used in industrial processing and in cleaning products for almost 50 years, being effective and economic emulsifying, wetting agents, dispersants and solubilizers. Cleaning products containing these surfactants are disposed of mainly by discharge into wastewater, which receives biological treatment in wastewater treatment systems. However, surface-active agents interact with eukaryotic cell membranes leading to biological damage at high concentrations. Tetrahymena pyriformis was used here as model organism to assess the effects of Triton X-100 through a series of in vitro cytotoxicity tests. Growth rates and morphological changes were, by their simplicity and reproducibility, the simplest toxicological assays. Cytoskeleton analysis seemed to be related with phagocytosis rate. Viability was evaluated by two different tests. Calcein AM/EthD-1 was used to assess T. pyriformis membrane damage during the 48-h experiment. The colorimetric MTT assay proved to be highly sensitive even at very short periods of Triton X-100 exposure. Tests performed in this study included simple and fast bioassays that provide overall information on the morphological and physiological state of cells exposed to different non-lytic and lytic concentrations of Triton X-100.     

Influence of ceramides in the solubilization of stratum corneum lipid liposomes by C(12)-betaine/sodium dodecyl sulfate mixtures.

The solubilization of liposomes modeling the stratum corneum (SC) lipid composition and those obtained varying the proportion of ceramides by means of dodecyl betaine (C(12)-Bet)/sodium dodecyl sulfate (SDS) mixtures was studied. 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 the free surfactant concentration was always similar to its critical micelle concentration (CMC) indicates that the liposome solubilization was mainly ruled by the formation of mixed micelles. The mole fraction of the zwitterionic component (X(zwitter)) of 0.4 showed the lowest ability to saturate or solubilize liposomes, although exhibiting the highest degree of partitioning into liposomes. This X(zwitter) corresponded to the highest derivation of the CMCs of these mixtures (negative synergism) and to the highest reduction in the skin irritation with respect to the anionic component. Higher and lower proportion of ceramides in the mixture led to a fall and to a rise in both the activity and the partitioning of a specific surfactant mixture (X(zwitter)=0.4). This finding could be related to the recently reported dependences of the level of ceramides in skin and function barrier abnormalities. Comparison of the present Re and K values with those reported for phosphatidylcholine (PC) liposomes shows that, although SC liposomes were more resistant to the action of surfactant mixtures, the surfactant partitioning into SC bilayers was similar to that reported for PC ones in all cases.     

Influence of the level of ceramides on the permeability of stratum corneum lipid liposomes caused by a C12-betaine/sodium dodecyl sulfate mixture.

The sublytic interactions of a mixture of N-dodecyl-N, N-dimethylbetaine dodecyl betaine (C12-Bet)/sodium dodecyl sulfate (SDS) (mole fraction of the zwitterionic surfactant=0.6) with stratum corneum (SC) lipid liposomes varying the proportion of ceramides type III (Cer) were investigated. The surfactant/lipid molar ratios (Re) and the bilayer/aqueous phase partition coefficients (K) were determined by monitoring the changes in the fluorescence intensity of liposomes due to the 5(6) carboxyfluorescein (CF) released from the interior of vesicles. The fact that the free surfactant mixture concentration was always lower than its critical micelle concentration indicates that permeability changes were ruled by the action of surfactant monomers in all cases. Higher and lower Cer proportions than that of the SC lipids led to a fall and to a rise in the activity of the surfactant mixture on these bilayer structures. However, the surfactant partitioning into liposomes (or affinity with these bilayer structures) increased as the proportion of Cer increased up to the highest value was achieved for a Cer proportion similar to that in the SC lipids (about 40-45%). Thus, at low Cer proportions the ability of the surfactant mixture to alter the permeability of these bilayer structures was higher than that for liposomes approximating the SC lipid composition despite their reduced partitioning into liposomes. These findings are in agreement with the recently reported dependencies of the level of ceramides in skin lipids and function barrier abnormalities and could explain in part these dependencies.     

Preparation of microcapsules with narrow-size distribution by complex coacervation: Effect of sodium dodecyl sulphate concentration and agitation rate

In this paper, microcapsules with narrow-size distribution, in which the core materials are a kind of suspension containing pigment scarlet powders dispersed in dyed tetrachloroethylene with Span-80 as an emulsifier, are prepared by complex coacervation through controlling sodium dodecyl sulphate (SDS) concentration and agitation rate. The microcapsules, formed in optimized process of 0.01 wt% SDS and 800 rpm, are ～40 μm in diameter. The phase diagram for the gelatin/SDS/water system indicates that the concentration of SDS in the experiments is outside of the complex formation zone to form a gelatin–SDS complex. Consequently, SDS preferential adsorbs and enriches on the surface of the core droplets due to its higher surface activity. Then, gelatin deposits with SDS at the core droplet/water interface to form a primary layer of complexation. Subsequently, with the pH lower than the isoelectric point of gelatin, complex coacervate of gelatin and gum arabic grows on the primary layer surface and finally deposits on the droplets to form a secondary layer. On the whole, the research indicates that the existence of SDS not only decreases the droplet diameters and centralizes the droplets size distribution, but also accelerates coacervation of gelatin and gum arabic to reach the core droplet/water interface, forming no aggregating microcapsules.     

Levels of enzymatic antioxidants activities in mononuclear cells and skin reactivity to sodium dodecyl sulphate

Chemical irritants are able to produce several biological modifications of the skin, including the direct or indirect production of cytokines and reactive oxygen species leading to an inflammatory reaction. This report examines the existence of a possible correlation between the skin sensitivity to the irritant sodium dodecyl sulphate (SDS) and the activity of the enzymatic antioxidants. In twenty-three healthy subjects the evaluation of the epidermal and peripheral blood mononuclear cells (PBMCs) activities of Superoxide Dismutase (SOD) and Catalase (Cat) demonstrate a significant correlation (r= 0,85 and p< 0,005 for SOD, and r= 0,87 and p< 0,0001 for Cat). Based on this result, on a further group of normal subjects (n=13) we studied the link between the threshold dose of skin reactivity to SDS and the activities of the enzymatic antioxidants in PBMCs. The degree of skin modification induced by SDS, applied at different concentrations for 24 hrs, was determined by means of Trans Epidermal Water Loss (TEWL), Erythemal Index or by Visual Score (VS). The minimal dose of the irritant capable of inducing skin modifications, was significantly correlated with SOD (r=0,77) and Cat (r=0,81) activities in PBMCs, and the modification of TEWL or EI were inversely correlated with levels of antioxidants in PBMCs (r=-0,62 for SOD and r=-0,66 for Cat). Our results indicate that the skin reactivity to irritants can be modulated by the levels of antioxidants, and suggest a possible therapeutical approach in preventing irritant contact dermatitis.