Biomedical Engineering Reference
In-Depth Information
Fig. 15
Copolymers and bilayer conformation. (
a
) Chemical structures of the two selected copo-
lymers, PEG-
b
-PBD and PEG-
b
-PMAzo444. (
b
) Cartoon of a polymersome and cartoon depicting
the conformation of both copolymers within the bilayer for an ePBD-iPAzo vesicle. The PEG-
b
-
PBD copolymer is always in a coil-coil state. In the absence of UV light, the hydrophobic LC block
of the PEG-
b
-PMAzo444 copolymer has a rod-like conformation (corresponding to a nematic
state). Under UV illumination, isomerization of the mesogenic groups induces a conformational
change of the polymer backbone to a disordered, isotropic state. The net effect of UV exposure is
two-fold: at the molecular scale, the projected area of the LC block is increased; at the mesoscopic
scale, the spontaneous curvature of the bilayer is increased. (
c
) Schematic representation of pore
opening driven by outward curling (for ePBD-iPAzo)
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