UV light and thermo-sensitive disassembling and release property of the assembly of cinnamic acid and poly(ethyleneimine)

Microspheres that were sensitive to temperature change and UV irradiation were developed by utilizing cinnamic acid (CA) as a physical cross-linker for poly(ethyleneimine) (PEI). The microspheres were disintegrated 4 h after being subjected to UV irradiation (λ = 365 nm, 400 W) for 30 min. In addition, the microspheres were stable at a low temperature (e.g. 30°C), but they were disintegrated upon being heated to 70°C. The release of fluorescein isothiocyanate-dextran loaded in the microsphere was triggered by UV irradiation and temperature change, possibly because the integrity of the microspheres was sensitive to the two kinds of stimuli.