Visible-Light Responsive Nanocapsules for Wavelength-Selective Release of Natural Active Agents

A breakthrough feature of visible-light responsive polymer nanocapsules relies on the possibility of customizing the release of the cargo material via precise tuning of the triggering wavelength in the visible spectrum. Here, visible-light responsive polymer nanocapsules are successfully fabricated through interfacial miniemulsion polymerization, introducing a comonomer based on modified ortho-substituted azobenzene in the capsule shell. Thyme essential oil and a model drug molecule, Coumarin-6, are encapsulated as core materials. Continuous irradiation with sunlight or visible light at different wavelenghts gives rise to smooth release patterns whose kinetics is studied as a function of the wavelength and intensity of the light source. Interestingly, an on-off release behavior is achieved when the capsules are irradiated with white or green light. Considering that visible light is readily available and unharmful to human beings, these intelligent delivery platforms are potentially applicable in a wide range of applications requiring a more sustainable approach, such as crop protection, cosmetics and packaging.