Niosomes based on the nonionic surfactant Tween 80 and cholesterol and modified with cationic surfactants (cetyltrimethylammonium bromide or its carbamate-bearing analog) were formed by the thin film ...hydration method. Such a modification of niosomes provides an increase in their ζ potential up to 60 mV, whereas the hydrodynamic diameter of the particles is 100 nm and remains nearly unchanged when the content of the cationic surfactant is varied from 1 to 3 wt.%. The inclusion of anti-inflammatory drug indomethacin in niosomes makes it possible to exceed its limiting solubility in water by nearly 20 times. The dialysis method demonstrated an increase in the release time of the encapsulated drug by 1.5 times, which is a prerequisite for its prolonged action in biosystems. The study of the kinetics of indomethacin cleavage in alkaline media revealed that the niosomes enhanced the stability of the drug providing protection against hydrolytic destruction processes.
The review focuses on the lipid based nanocarriers, with special attention paid to natural bioactive payloads. First, micelles and microemulsions are considered as very attractive colloidal ...nanocontainers that allow for marked improving the solubility of hydrophobic bioactives. Further, liposomal vehicles are reviewed, with both advantages and limitations discussed. Literature assay covers up-to-date information of about last three to five years, although brief background is given on the pioneer works addressing the liposomes and their evolution from bench to bedside. Final part of the review is devoted to the modern modifications of vesicular nanocarriers which can be adapted to specific administration way due to improved targeting properties, permeability, mucoadhesiveness and possibility to cross biological barriers. Therein, such kinds of nanocarriers as transfersomes, niosomes, ethosomes, chitosomes are evaluated; and separate sections focus on the natural based formulations, i.e., phytosomes and invasomes.
A series of microemulsions based on oleic acid and Tween 80, modified with piperidinium surfactants, have been obtained and characterized. The effect of additives on the size, stability, and ...solubilization effect of the formed systems with respect to hydrophilic (rhodamine B) and hydrophobic (indomethacin) substances have been investigated. Varying of the components ratio has allowed preparation of the microemulsions with strongly different viscosity: from easy-flowing formulations to gels. Kinetic parameters describing release of the substrates from the microemulsions have been obtained. In vivo tests of the anti-inflammatory action of the microemulsions loaded with indomethacin have shown that the presence of piperidinium surfactants enhances the therapeutic effect of the drug.
The aggregation behavior, solubilization effect, and catalytic activity of hexadecylpiperidinium surfactants (including ones functionalized with hydroxyl substituents) have been investigated. The ...kinetics of hydrolytic cleavage of the irreversible cholinesterase inhibitor ethyl
p
-nitrophenyl ethylphosphonate (armine) in the micellar solutions of these surfactants has been studied using spectrophotometry. It has been shown that the micellar catalytic effect increases in the following order: methyl(hexadecyl)piperidinium bromide < methyl(hexadecyl)-3-hydroxypiperidinium bromide < hexadecyl(2-hydroxyethyl)piperidinium bromide < 2-hydroxyethyl-4-hydroxypiperidinium bromide. The acceleration observed can be as high as almost two orders of magnitude.
This review is devoted to self-organizing systems based on amphiphilic compounds of different types, i.e., open-chain and macrocyclic ones. Conventional colloidal surfactants have been considered ...both in the individual form and in the presence of modifiers, including electrolytes and cosurfactants. Special attention has been focused on the role of structural factors, in particular, an analysis has been performed for the cases of the most pronounced influence of surfactant structure (the nature of head groups and counterions, the passage to dicationic surfactants, and the occurrence of calix4arene cores) on the aggregation characteristics, morphological behavior, and functional activity of the systems. Macrocyclic amphiphiles are typical objects of supramolecular chemistry. The final part of the review presents the comparison between two types of the systems: (1) amphiphilic calixarenes (covalent functionalization of macrocycles with alkyl fragments) and (2) calixarene–surfactant binary composites (noncovalent modification of the macrocyclic platform).
Dicationic imidazolium surfactants of the 1,1′-(2-hydroxypropan-1,3-diyl)bis(3-alkyl-1
H
-imidazol-3-ylium)chloride series with a variable hydrophobic chain length have been synthesized and ...characterized. The values of their critical micelle concentration have been determined by tensiometry, conductometry and spectrophotometry. Significant antimicrobial activity of these surfactants against a number of pathogenic bacteria and fungi was revealed. It was found that decyl and dodecyl derivatives turned out to be leader compounds, which surpassed reference antibiotics in their action and showed activity against resistant strains. The kinetic parameters reflecting the high catalytic effect of the tested dicationic imidazolium surfactants in the alkaline hydrolysis of 4-nitrophenyl esters of phosphonic, phosphoric, and toluenesulfonic acids have been obtained.
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•Novel dicationic surfactants bearing morpholinium moieties are synthesized.•Morpholinium geminis show superior solubilization activity toward a drug.•Solubilization of a drug results ...in pKa shift.•Mutual influence of the guest/host properties occurs upon the solubilization.•Multifactor mechanism of the drug solubilization is realized.
Herein, novel dicationic surfactants bearing morpholinium moieties in polar group, 14-s-14 Mor (s=4, 6, 8, 10) are synthesized, and their aggregation behavior is studied and compared with reference surfactants, single-head morpholinium surfactant Mor-14, typical gemini with ammonium head group and dicationic surfactants with heterocyclic polar fragment. Geminis studied are found to exhibit superior solubilization capacity toward a pH indicator thymolphthalein and an inflammatory drug indomethacin, exceeding that of reference amphiphiles. The solubility of the probes is contributed by multifactor mechanism involving the solubilization in nonpolar core of micelles and periphery electrostatic interaction between micellar surface charge and ionic moieties of the drug. Mutual influence of the components occurs on their properties, including pKa shift of ionogenic groups of a guest molecule and decrease in critical micelle concentration of geminis.
Data characterizing the effect of electrolyte additives (sodium chloride and salicylate, polyacrylic acid) on the critical micelle concentration and the size of hexadecylpiperidinium surfactant ...aggregates, including those containing one or two hydroxyl groups, were obtained by tensiometry and dynamic light scattering methods. The solubilization effect of surfactant—electrolyte systems with respect to the hydrophobic dye probe Orange OT was evaluated. The conditions (pH, ratio of components) for the formation of soluble (nonstoichiometric) and insoluble (stoichiometric) polymer-colloidal complexes were determined for a surfactant—polyacrylic acid system.
Systematic data on the aggregation behavior of novel 3-hydroxypiperidinium surfactants in aqueous solutions were obtained. The ability of the surfactants to solubilize hydrophobic compounds, ...including the Orange OT dye and biologically active flavonoid quercetin, was characterized. The maximally achieved limiting content of these substances in micellar solutions of 3-hydroxypiperidinium surfactants is by two to three times higher than that in solutions of their non-functionalized analogs. The solubility of quercetin depends on the pH of the medium, and the highest effect observed on going from water to micellar solutions of the studied surfactants reaches two orders of magnitude.
The aggregation behavior of mixed micellar solutions based on 2-hydroxyethylpiperidinium surfactants and nonionic surfactant Brij® 35 was investigated. The critical micelle concentrations determined ...by varying the component ratio suggest a negative deviation from the ideal mixing model (synergistic effect). It was demonstrated that the magnitude of the deviation from ideal mixing behavior depends on the alkyl chain length in the cationic surfactant and on the component ratio. The solubilization effect of the binary systems on hydrophobic substances was evaluated taking Orange OT dye and ibuprofen drug as examples. It was found that the piperidinium surfactants studied, both individually and in compositions containing up to 50% of the nonionic surfactant, exhibit high antimicrobial activity comparable to that of commercial antibiotics.
