Redox-Responsive Amphiphilic Macromolecular [2]Pseudorotaxane Constructed from a Water-Soluble Pillar[5]arene and a Paraquat-Containing Homopolymer

Here we report a redox-responsive host–guest complex between a new water-soluble pillar[5]­arene (WP5) and a paraquat derivative. Compared with the neutral form of the paraquat derivative that binds WP5 weakly, its dication form binds WP5 much more strongly. Furthermore, we utilize this new water-soluble redox-responsive molecular recognition motif to construct the first pillararene-based amphiphilic macromolecular [2]­pseudorotaxane, which self-assembles into redox-responsive polymeric vesicles in water. Such pillararene-based supramolecular vesicles were further used to construct a drug delivery system to encapsulate and controlled release DOX·HCl, an anticancer drug. The uptake of these DOX·HCl-loaded supramolecular vesicles by cancer cells was studied with confocal laser scanning microscopy. Meanwhile, DOX·HCl-loaded supramolecular vesicles showed anticancer activity in vitro comparable to free DOX·HCl under the examined conditions.