β-Cyclodextrin-induced fluorescence enhancement of a thermal-responsive azobenzene modified polydiacetylene vesicles for a temperature sensor

We devised a novel PDA-based model with linear temperature dependence of fluorescence intensity in a wide temperature range, which could be applied as an accurate temperature sensor in chemical or bio-environment due to the biocompatibility of polydiacetylene (PDA) vesicles. The fluorescence intensity was remarkably enhanced after the adding of β-cyclodextrin (β-CD), and the fluorescent signal remained linear proportional to the temperature in the range from 25 °C to 80 °C. Further, photo-controlled inclusion and exclusion reaction of the azobenzene-containing PDA vesicles with β-CD had been used to act as driving force to induce the change of fluorescence intensity for the composite vesicles. Fluorescence spectroscopy and fluorescence microscopy were used to characterize the fluorescence properties of system. Two-dimensional NMR was used to characterize the interaction between cyclodextrin and azobenzene functional groups. Our work provided a novel system that combines photo-chemistry and host-guest chemistry for a photo-stimulus-responsive vesicle and should be valuable in application in PDA-based temperature sensor.