Development of a Non-ionic Azobenzene Amphiphile for Remote Photocontrol of a Model Biomembrane

LAURA FANANI; LUCIANO BENEDINI; BRUNO MAGGIO; ALEJANDRA SEQUEIRA; VERÓNICA DODERO

JOURNAL OF PHYSICAL CHEMISTRY B - (Print)

AMER CHEMICAL SOC

Lugar: Washington; Año: 2016 vol. 5 p. 4053 - 4063

1520-6106

We report the synthesis and characterization of asimple non-ionic azoamphiphile, C12OazoE3OH which behavesas an optically-controlled molecule alone and in a biomembrane-environment. First,Langmuir monolayer and Brewster angle microscopy (BAM) experiments showed that pureC12OazoE3OH enriched in the (E) isomer was able to form solid-like mesophase even at low surfacepressure associated with supramolecular organization of the azobenzenederivative at the interface. On the other hand, pure C12OazoE3OHenriched in the (Z) isomer formed a less solid-like monolayer dueto the bent geometry around the azobenzene moiety. Second, C12OazoE3OHis well-mixed in a biological membrane model, Lipoids75TM (up to 20%mol), and photoisomerization among the lipids proceeded smoothly depending onlight conditions. It is proposed that the cross-sectional area of the hydroxyltriethylenglycol head of C12OazoE3OH inhibits azobenzenesH-aggregation in the model membrane, thus the tails conformation change due tophotoisomerization is transferred efficiently to the lipid membrane. We showedthat the lipid membrane effectively senses the azobenzene geometrical changephoto-modulating some properties, like compressibility modulus, transitiontemperature and morphology. In addition, photomodulation proceeds with a colorchange from yellow to orange, providing the possibility to externallymonitoring the system. Finally, Gibbs monolayers showed that C12OazoE3OHis able to penetrate the highly packing biomembrane model, thus C12OazoE3OHmight be used as photoswitchable molecular probe in real systems.