Effect of Poloxamer 188 on the Osmotic Response of Cell Membranes

Abstract

the effect of glycerol on the surfactant -lipid system in terms of surfactant selfassociation (critical micelle concentration, CMC), membrane partitioning (partition coefficient K and aHmic), and the onset of membrane solubilization (i.e., bilayer-to-micelle transition, characterized by a specific surfactant-to-lipid mole ratio in the membrane denoted Resat) by isothermal titration calorimetry (ITC). One effect expected for glycerol is its tendency to 'salt out' hydrophobic molecules. This promotes all aggregation phenomena (K increases, CMC decreases) but has little effect on the balance between the aggregates (Resat const.). Furthermore, glycerol gradually dehydrates the polar head group, which renders the effective molecular shape more favorable for a bilayer (K increases) whereas micellization is much less affected (CMC ~const) so that bilayers are stabilized compared to micelles (Resat increases). Our results indicate that the behavior of the sugar based surfactant octyl glucoside seems governed by the salting out effect, whereas for ethylene oxide surfactant C12EO8, headgroup dehydration seems to be the key effect explaining the effects of glycerol.

Effects of the interaction and surface morphology of mixed DPoPE/Poloxamer 188 monolayers and thin liquid films

“…The noncytotoxic biosurfactant Poloxamer 188 (P188) is a three-block copolymer (hydrophilic polyethylene oxide, PEO, hydrophobic polypropylene oxide, PPO, hydrophilic polyethylene oxide, PEO) with amphiphillic structure which is known to repair damaged membranes and thus to restore the structural integrity and function of the cells both in vitro and in vivo. [17][18][19][20][21][22][23] P188 has a molecular weight of about 8400 Da and its hydrophilic part is about 80% of the total molecular weight. The PEO chains (each including 76 monomer units) are hydrophillic due to their short carbon units between the oxygen bridges whereas the PPO center (formed from 29 monomers) is hydrophobic due to the larger propylene unit.…”