The
kinetics of clustering unilamellar vesicles induced by inverse
Pluronics [poly(propylene oxide)<sub><i>m</i></sub>–poly(ethylene
oxide)<sub><i>n</i></sub>–poly(propylene oxide)<sub><i>m</i></sub>, PO<sub><i>m</i></sub>–EO<sub><i>n</i></sub>–PO<sub><i>m</i></sub>]
was investigated via experiments and molecular dynamic simulations.
Two important factors for controlling the networking kinetics are
the membrane defects, presumably located at the interfacial region
between two lipid domains induced by acyl chain mismatch, and the
polymer hydrophobicity. As expected, the clustering rate increases
significantly with increasing bilayer defects on the membrane where
the insertion of PPO is likely to take place because of the reduced
energy barrier for the insertion of PO. The hydrophobic interaction
between the PO blocks and membranes with the defects region dictates
the “anchoring” kinetics, which is controlled by the
association–dissociation of PO with the lipid membrane. As
a result, the dependence of clustering rate on polymer concentration
is strongly influenced by the hydrophobicity of the PO blocks. Nevertheless,
longer PO blocks show stronger association with the membrane, resulting
in faster consumption of the “active” sites made of
these defect regions (causing mostly “invalid” insertions)
with increasing polymer concentration, hence inhibiting the formation
of large networking clusters, while shorter PO blocks undergo more
frequent association with/dissociation from the defects, allowing
continuous formation of larger clusters with increasing polymer concentration.
This study provides important insights into how the organization and
dynamics of a biomembrane influence its interaction with foreign amphiphilic
molecules
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