1 research outputs found
Development of a Nonionic Azobenzene Amphiphile for Remote Photocontrol of a Model Biomembrane
We report the synthesis and characterization
of a simple nonionic
azoamphiphile, C<sub>12</sub>OazoE<sub>3</sub>OH, which behaves as
an optically controlled molecule alone and in a biomembrane environment.
First, Langmuir monolayer and Brewster angle microscopy (BAM) experiments
showed that pure C<sub>12</sub>OazoE<sub>3</sub>OH enriched in the
(<i>E</i>) isomer was able to form solidlike mesophase even
at low surface pressure associated with supramolecular organization
of the azobenzene derivative at the interface. On the other hand,
pure C<sub>12</sub>OazoE<sub>3</sub>OH enriched in the (<i>Z</i>) isomer formed a less solidlike monolayer due to the bent geometry
around the azobenzene moiety. Second, C<sub>12</sub>OazoE<sub>3</sub>OH is well-mixed in a biological membrane model, Lipoid s75 (up to
20%mol), and photoisomerization among the lipids proceeded smoothly
depending on light conditions. It is proposed that the cross-sectional
area of the hydroxyl triethylenglycol head of C<sub>12</sub>OazoE<sub>3</sub>OH inhibits azobenzenes H-aggregation in the model membrane;
thus, the tails conformation change due to photoisomerization is transferred
efficiently to the lipid membrane. We showed that the lipid membrane
effectively senses the azobenzene geometrical change photomodulating
some properties, like compressibility modulus, transition temperature,
and morphology. In addition, photomodulation proceeds with a color
change from yellow to orange, providing the possibility to externally
monitor the system. Finally, Gibbs monolayers showed that C<sub>12</sub>OazoE<sub>3</sub>OH is able to penetrate the highly packing biomembrane
model; thus, C<sub>12</sub>OazoE<sub>3</sub>OH might be used as photoswitchable
molecular probe in real systems