Figure 8.

Examples of drug release by competitive guest displacement. (A) Crown ether motifs incorporated within a hydrogel dictated material swelling in a manner that could be controlled by the addition of K⁺ guests for the macrocycle. The addition of this competitive guest increased material swelling which would lead to drug release. Figure adapted with permission from reference ¹⁵⁰. Copyright 2013 Elsevier. (B) Mesoporous silica nanoparticles were surface-functionalized with a guest motif having moderate binding affinity to cucurbit[7]uril. As a competitive lysine guest was added in the presence of decarboxylase enzyme, the macrocycle preferentially bound the enzymatically processed lysine, which displaced the macrocycle and released drug from within the silica nanopores. Figure adapted with permission from reference ¹⁵¹. Copyright 2011 John Wiley and Sons.