– Benzo-18-crown-6-ether (B18C6) is an organic compound used to create stable microcapsule responsive layers, which can be assembled into bilayer microcapsules. For instance, 18-Crown-6-ether is employed to prepare a responsive layer and then coated with a K+-stabilized G-quadruplex cross-linked hydrogel layer. When Mg2+ ions are present, 18-Crown-6-ether and K+ ions enable dissociation and locking with the G-quadruplex cross-linked layer, allowing for switchable controlled release of the load.