Stimuli-Responsive Drug-Delivery Systems Based on Supramolecular Nanovalves

From motor proteins tomolecularmachines, supramolecular chemistry has been revealed as a remarkable link to bridge the gap between biology, chemistry, and materials. Taking inspiration from the dynamic, reversible, and directional manner of non-covalent interactions that can respond to diversiform external stimuli, supramolecular nanovalves installed on the surface of inorganic or hybrid nanocarriers have received extensive attention in stimuli-responsive delivery of small drug molecules, implying their outspread bioapplications in cancer/gene therapy, biomedical application, and antimicrobial regulations. The state of supramolecular nanovalves could be well regulated by switching the conformation or the assembled/disassembled state of the assemblies. This tutorial review lays the foundation for a better understanding of the significant and typical intelligent drug-delivery systems immobilized with supramolecular polymers or supramolecular pseudorotaxanes as the gating entities of nanovalve-based molecular machines, by showing their chemical structures, operation modes, and release modalities triggered by various actuations at molecular scale. In particular, relevant perspectives of supramolecular therapeutics will also be elaborated upon.