Open AccessContrasting Topological Effect of PEG-Containing Amphiphiles to Natural Lipids on Stability of Vesicles
Author(s) -
Rui Li,
Takahiro Muraoka,
Kazushi Kinbara
Publication year - 2016
Publication title -
langmuir
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.042
H-Index - 333
eISSN - 1520-5827
pISSN - 0743-7463
DOI - 10.1021/acs.langmuir.6b00713
Subject(s) - amphiphile , vesicle , chemistry , supramolecular chemistry , amphiphilic molecule , peg ratio , chirality (physics) , topology (electrical circuits) , thermal stability , membrane , molecule , organic chemistry , copolymer , polymer , biochemistry , chiral symmetry breaking , physics , mathematics , finance , quantum mechanics , combinatorics , economics , nambu–jona lasinio model , quark
Topology of amphiphiles is important to control physicochemical properties of supramolecular assemblies. Nature demonstrates higher stability of membrane composed of lipids with a macrocyclic aliphatic tail than those with linear tails, which likely results from the restricted molecular structures of the macrocyclic lipids, allowing for closer molecular packing. In contrast, here we report that a PEG-containing macrocyclic amphiphile shows lower stability of vesicles than the corresponding acyclic one. The macrocyclic amphiphile consists of an aromatic hydrophobic part with chirality in which both ends are strapped by octaethylene glycol via phosphoric ester groups, while the acyclic amphiphile bears tetraethylene glycol chains attached to both ends of the hydrophobic part. Because of the thermoresponsive property of PEG to change its conformation, the hydrophobic part of the macrocyclic amphiphile undergoes a larger thermal conformational change than that of the acyclic one. In addition, the cyclic amphiphile has a larger molecular area, which likely reduces the vesicular stability compared with the acyclic one. Such a contrasting topological effect caused by macrocyclization at the aliphatic part seen in the natural system and at the hydrophilic part demonstrated in this study leads to expand the molecular design of amphiphiles for both increasing and decreasing the stability of vesicles by molecular topology.