Professor Kingo Uchida's group at Ryukoku University's Faculty of Advanced Science and Engineering has succeeded in developing a "crystal capsule that emits inclusions by irradiating light" that imitates the fruit of the impatiens balsa that flies off seeds.
This crystal capsule utilizes a phenomenon called photosalient phenomenon, in which crystals crack or jump when irradiated with light.It is thought that when exposed to light, a photoreaction occurs in the organic molecules that make up the crystal, and the size of the molecule changes from the initial state, such as by changing to another molecule, causing strain on the crystal surface and destroying the crystal. Has been done.
There is no other capsule in the world that emits what is contained in a capsule with light.This group, which has continued research on the photoresponsive substance diarylethene (DAE), has been working on the development of photoresponsive capsules using DAE.
Here, we have found that by dissolving the substance to be encapsulated and the molecule 1o of DAE in an organic solvent, a DAE crystal capsule containing the substance can be produced by a normal recrystallization method.When this crystal capsule was irradiated with ultraviolet light, it was broken by the photosalient effect, and inclusions (green fluorescent dye in the experiment) spread around the capsule.
It was also found that the size of the obtained crystal capsule can be reduced by shortening the recrystallization time.When the minicapsules were exposed to ultraviolet light, they also broke and released inclusions.
It was also confirmed that crystals can be destroyed even with near-infrared light in the wavelength range that penetrates deeply into the living body, which is called the "window of the living body".This indicates that even after being introduced into a living body, the capsule can be light-destroyed inside and used for releasing drugs and the like.
Furthermore, since the molecules are arranged regularly in the crystal, it was found that the photosalient phenomenon can be induced only in a specific crystal and the capsule destruction can be controlled by irradiating ultraviolet light while changing the direction of the plane of polarization.
In this way, the function of emitting inclusions by remote control via light is expected to have various applications.
Paper information:[Chemical Science] Molecular crystalline capsules that release their contents by light
