Thermo-responsiveness of giant vesicles supporting hindered amines as reactive sites

The thermo-responsiveness of giant vesicles supporting 2,2,6,6-tetramethylpiperidine (TP), the hindered amine, and its reactivity on the vesicle surface were evaluated with the aim of creating a new artificial biomembrane model using the polymer vesicles having reactive sites on the surface. A light-scattering study demonstrated that the TP-supporting spherical vesicles reversibly self-assembled by responding to temperature changes. The vesicles underwent a two-step disruption by heating, the first, transformation into much smaller and deformed vesicles, and the second, transformation into micelles through the budding separation from the granulated vesicle surface. The vesicles were rapidly restored by cooling due to the aggregation of the micelles. The TP supported on the vesicle surface underwent oxidation by H2O2 to convert into 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO), accompanied by transformation from the spherical shape into a sheet. The TEMPO underwent a further reduction by L(+)-ascorbic acid into the hydroxylamine.