Partition and Solubilization of Phospholipid Vesicles by Noncovalently Constructed Oligomeric-like Surfactants

Abstract

This work has investigated the interaction of 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) vesicles with oligomeric surfactants noncovalently formed by sodium dodecyl sulfate (SDS) and a series of polyamines, 1,3-diaminopropane (PDA), triamine, spermidine, and spermine. The partition coefficients (P) of these surfactants between lipid bilayers and the aqueous phase are measured by isothermal titration microcalorimetry (ITC), showing that the P value increases and the Gibbs free energy of the partition becomes more negative with increasing oligomerization degree of the surfactants. This changing trend is similar to that of synthetic oligomeric surfactants regardless of the charge properties, suggesting that the polyamine and SDS molecules interact with the DOPC bilayer simultaneously. Meanwhile, the DOPC solubilization by these surfactants is evaluated by the effective surfactant-to-lipid molar ratios for the onset (R e sat ) and end (R e sol ) of the solubilization process, which are determined from the phase boundaries obtained by ITC, turbidity, and dynamic light scattering measurements. With the increment of oligomerization degree, the R e sat and R e sol values increase anomalously and are much larger than those of the synthetic surfactants with the same oligomerization degree, suggesting that noncovalently constructed oligomeric surfactants exhibit lower solubilization ability to phospholipid vesicles than the corresponding covalent oligomeric surfactants. Therefore, the noncovalently constructed oligomeric-like surfactants facilitate strong partition but weak solubilization to phospholipid vesicles, which may provide a useful strategy to mildly adjust the permeation and fluidity of phospholipid vesicles with solubilization delay.

Noncovalent Bile Acid Oligomers as Facial Amphiphilic Antimicrobials

“…It is known that the micellization of sodium salts of bile acids upon increasing concentration is a stepwise process. The formation of premicelles is hypothesized in the first step below CMC and further associate with each other at a larger concentration, above CMC. − The CMC values of sodium cholate and sodium deoxycholate are 11.0 mM and 4.0 mM, respectively, and their surface tension values at CMC (expressed as γ CMC ) are all >46 mN·m –1 . , When the polyamines are added, surface tension values are reduced and all γ CMC values become stable in the range of 40–45 mN·m –1 , although some curves decrease first to thereafter reach this range. The final surface tension is dictated by the molecular packing of the unbound and bound bile acids with the polyamines at the air/water interface.…”

“…53−56 The CMC values of sodium cholate and sodium deoxycholate are 11.0 mM and 4.0 mM, respectively, and their surface tension values at CMC (expressed as γ CMC ) are all >46 mN•m −1 . 57,58 When the polyamines are added, surface tension values are reduced and all γ CMC values become stable in the range of 40−45 mN•m −1 , although some curves decrease first to thereafter reach this range. The final surface tension is dictated by the molecular packing of the unbound and bound bile acids with the polyamines at the air/water interface.…”

Soybean-Oil-Based CO2-Switchable Surfactants with Multiple Heads

“…The advent of oligomeric surfactants has bridged the gap between the two surfactant types. Due to their various characteristics, such as high efficiency, multifunctionality and environmental friendliness, the oligomeric surfactants have recently emerged as new generation surfactants and are most likely to find a widespread use [ 6 , 7 , 8 , 9 ].…”