jp0c00553_si_001.pdf (760.26 kB)
Influence of the Headgroup on the Interaction of Poly(ethylene oxide)-Poly(propylene oxide) Block Copolymers with Lipid Bilayers
journal contribution
posted on 2020-03-16, 14:03 authored by Wenjia Zhang, Joseph M. Metzger, Benjamin J. Hackel, Frank S. Bates, Timothy P. LodgeThe lipid headgroup
plays an important role in the association of polymers with lipid
bilayer membranes. Herein, we report how a glycerol headgroup versus
a choline headgroup affects the interaction of poly(ethylene oxide)-b-poly(propylene oxide) (PEO-PPO) block copolymers with
lipid bilayer vesicles. Unilamellar vesicles composed of phosphatidylcholine
and phosphatidylglycerol at various molar ratios were used as model
membranes. The interactions between the block copolymers and lipid
bilayers were quantified by pulsed-field gradient nuclear magnetic
resonance (PFG-NMR) based on the distinctly different mobilities of
free and bound polymers. All the investigated polymer species showed
significantly higher binding with 1-palmitoyl-2-oleoyl-sn-glycero-3-phospho-(1′-rac-glycerol) sodium salt (POPG) liposomes
than with 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine
(POPC) liposomes, indicating stronger association with the glycerol
headgroup compared to the choline headgroup. This effect did not become
significant until the composition of mixed POPC/POPG liposomes contained
more than 20 mol % POPG. A plausible explanation for the enhanced
polymer binding with POPG invokes the role of hydrogen bonding between
the glycerol headgroup and the ether moieties of the polymers.