A peptide dendron-based shrinkable metallo-hydrogel for charged species separation and stepwise release of drugs

A shrinkable supramolecular metallo-hydrogel based on the L-glutamic acid dendron and magnesium showed reversible volume-phase transition depending on pH changes. The hydrogel further showed selective shrinkage upon addition of positively charged species, while it remained in the gel state when negatively charged species were incorporated. Based on this property, the gel could be used as the matrix to efficiently separate ionic dye mixtures, in which the cationic dye was incorporated predominantly in the shrunken gel, while the negatively charged dye was released into the aqueous solution. More interestingly, the shrinkable gel can be used as a model drug-delivery vehicle for the stepwise release of a two-component drug system, in which the negatively charged drug is released first and then the second component is released with a pH trigger.