The disclosure provides cross-linked materials that include multivalent cross-linking agents that bind an exogenous target molecule； and conjugates that include two or more separate affinity ligands bound to a conjugate framework, wherein the two or more affinity ligands compete with the exogenous target molecule for binding with the cross-linking agents and wherein conjugates are cross-linked within the material as a result of non-covalent interactions between cross-linking agents and affinity ligands on different conjugates. The conjugates also include a drug.
