“…More importantly, selective MOFs and their composites exhibit stimuli-responsive behaviors toward endogenous and exogenous stimuli when being applied as drug delivery systems. , For instance, zeolitic imidazolate framework-8 (ZIF-8), composed of Zn 2+ and 2-methylimidazole (a pH-sensitive group), was used for intracellular delivery of DNA polymerase and nucleic acid probes when the pH drops below 6 . Another type of MOF-based material, polydopamine-functionalized MIL-53(Fe), was reported to be loaded with an antitumor drug, camptothecin, with pH-sensitive drug release profiles …”