Facile Preparation of Chemically Cross-Linked Microgels by Irradiation of Visible Light at Room Temperature

We report on the facile preparation of chemically cross-linked microgels in mild conditions by using the reversed microemulsion technique. Sodium alginate has been modified by partially grafting phenol groups to the backbone, oil the basis of which microgels have been prepared by the irradiation of visible light in the presence of catalyst Ru(II) complex at room temperature. The irradiation of visible light instead of UV light or gamma rays brings many advantages. The mean diameters of the microgels are 15-40 mu m in aqueous solution and 5-15 mu m in the dried state. Although the size of the microgel is sensitive to the environment change, it presents excellent size stability in a broad range that covers the physiological condition. The applications of this biocompatible and biodegradable microgel in biology are greatly anticipated.