Oligopeptides are part of this nanovalve system in peptide modified mesoporous silica nanocontainers for the controlled release of drugs. The peptides decorating the surface of the particles have two functions: to act as stimuli responsive nanovalves and to ensure efficient cell uptake. The peptide sequence used in this study has a high selectivity towards cellular membranes and at the same time allows the suspension of the silica nanocarrier in water solutions in order to perform in vivo studies.
The system operated successfully under pH control (deprotonation of ferrocenedicarboxylic acid at pH = 4) in the presence of cucubituril, and redox control (oxidation of ferrocenedicarboxylic acid) in the presence of β-CD.
Redox-switchable pseudorotaxanes and bistablerotaxanes, having a cyclobis(paraquat-p-phenylene) (CBPQT4+) tetracationic ring, can be tethered to porous silica thin films and to MCM-4114 to act together as supramolecular and molecular nanovalves, respectively. In addition, a supramolecular nanovalve system (switchable pseudorotaxane) based on dibenzocrown-8/dialkylammonium ion complexation that responds to a range of bases.
The rotaxane-modified MCM-41 constitutes a class of organic-inorganic hybrid nanoparticle that utilizes the mechanical movement within a mechanically interlocked molecule to control trapping and release of guest molecules. The valve is controlled by simple redox chemistry with mild redox reagents.
A functioning nanomachine in the form of a supramolecular nanovalve that opens and closes the orifices to molecular-sized pores and releases a small number of molecules on demand is reported.
Light-driven dethreading in aqueous solution of the pseudorotaxane (BHEENCBPQT4.) by excitation of the external photosensitizer, 9-anthracenecarboxylic acid, in the presence of a sacrificial reductant. Dioxygen is used to effect rethreading.