Vesicular Properties of Stereoisomeric Surfactants

Abstract

All of the stereoisomeric forms of the surfactant, sodium 3-[2-methyl-4,5-bis(hexadecyloxymethyl)-1,3-dioxolan-2-yl]propane-1-sulfonate, have been prepared: the enantiomers (+)-1 and (−)-1, the racemate (±)-1 (by two different methods), and meso 2 and meso 3. Vortexed vesicles of these materials were characterized by dynamic laser light scattering, to give vesicle sizes, and by differential scanning calorimetry, to give bilayer phase transition temperatures and associated enthalpies. Different calorimetry results were obtained for (+)-1 [(−)-1], (±)-1, 2, and 3. In particular, a comparison of the results for (+)-1 [(−)-1] and (±)-1 indicated the operation of enantiomer discrimination. The criteria of the “absolute” method of stereochemistry applied to this study were not completely fulfilled.

DSC Analysis of Surfactant-Based Microstructures

“…13), with a maximum value at the equimolar (racemic) mixture and two minimum temperatures at the R isomer mole fractions of 0.2 and 0.8 in the mixture. Jaeger et al [120] found differences between DSC behavior of vesicles of enantiomers and racemate, but not as significant as those found by Morigaki et al [119]. This difference enabled the authors to qualitatively follow the kinetics of surfactant exchange between the R and the S isomer vesicles, following the disappearance of the 9.5°C peak and the rise of the 15°C peak at the time (Fig.…”

“…These temperatures correspond to the two eutectic mixtures of enantiomeric and racemic crystals, and the shape of the (pseudo) binary phase diagram indicates that the crystal of the racemate is a racemic compound, as in the case of the bulk compound. Chiral discrimination has been found in a number of DSC studies of phospholipid bilayers [120][121][122][123][124][125][126]. 14) when equimolar solutions of the R and S isomers were mixed.…”

Self-Assembly and Chiral Recognition of Chiral Cationic Gemini Surfactants

“…Compared with chiral single-chain surfactants, chiral gemini surfactants − can offer more possible chiral sites in alkyl chains, headgroups, spacer, and counterions. − Nevertheless, only a few works have studied the effect of chirality on the properties of chiral gemini surfactants. Mancini and co-workers − constructed three stereoisomeric cationic gemini surfactants with two methoxyl groups located at the chiral centers of the spacer.…”

“…More specifically, the chirality in the hydrophobic tail and counterion also affects the aggregation behavior of the chiral gemini surfactants. Jaeger et al , studied the vesicular and monolayer properties of the chiral gemini surfactants with two chiral centers in the two alkyl chains and found distinct differences in phase transition temperature, permeability, and monolayer characteristics. The stereochemical difference among the surfactants is more obvious in the monolayer than in the vesicles due to the tighter surfactant packing in the former.…”

How stereochemistry affects the physicochemical features of gemini surfactant based cationic liposomes

“…12,13 Furthermore, by comparing the efficiency of PS delivery by liposomes containing 1 or 3 to the glioblastoma cell lines, it was shown that the stereochemistry of the gemini affects some of the physicochemical features of mixed liposomes, the efficiency of delivery and the intracellular distribution of the drug. 14 While it is well known that the stereochemistry of the components can affect the morphology, 15 the stability 16 and the physicochemical features of lipid aggregates, 17 the correlation of the physicochemical and biological features is not always obvious.…”