A nested capsule having a first capsule held within a second capsule. Each of the first and second capsules has a shell that is a supramolecular cross-linked network, such as a cucurbituril supramolecular cross-linked network. Each capsule shell is obtained or is obtainable from the complexation of a composition including a host, such as cucurbituril, and one or more building blocks having suitable guest functionality for the host, thereby to form a supramolecular cross-linked network. The nested capsules are suitable for delivering and selectively releasing an encapsulant at a location.
