Hierarchically Self-Assembled Supramolecular Host–Guest Delivery System for Drug Resistant Cancer Therapy

In this report, a new star-like copolymer β-CD-<i>g</i>-(PNIPAAm-<i>b</i>-POEGA)_<i>x</i>, consisting of a β-CD core, grafted with temperature-responsive poly­(<i>N</i>-isopropylacrylamide) (PNIPAAm) and biocompatible poly­(oligo­(ethylene glycol) acrylate) (POEGA) in a block copolymer of the arms, was used to deliver chemotherapeutics to drug resistant cancer cells and tumors. The first step of the self-assembly process involves the encapsulation of chemotherapeutics through host–guest inclusion complexation between the β-cyclodextrin cavity and the anticancer drug. Next, the chain interaction of the PNIPAAm segment at elevated temperature drives the drug-loaded β-CD-<i>g</i>-(PNIPAAm-<i>b</i>-POEGA)_<i>x</i>/PTX inclusion complex to hierarchically self-assemble into nanosized supramolecular assemblies at 37 °C, whereas the presence of poly­(ethylene glycol) (PEG) chains in the distal end of the star-like copolymer arms impart enhanced stability to the self-assembled structure. More interestingly, this supramolecular host–guest nanocomplex promoted the enhanced cellular uptake of chemotherapeutics in MDR-1 up-regulated drug resistant cancer cells and exhibited high therapeutic efficacy for suppressing drug resistant tumor growth in an <i>in vivo</i> mouse model, due to the increased stability, improvement in aqueous solubility, enhanced cellular uptake, and partial membrane pump impairment by taking the advantage of PEGylation and supramolecular complex between this star-like copolymer and chemotherapeutics. This work signifies that temperature-sensitive PEGylated supramolecular nanocarriers with good biocompatibility are effective in combating MDR-1 mediated drug resistance in both <i>in vitro</i> and <i>in vivo</i> models, which is of significant importance for the advanced drug delivery platform designed to combat drug resistant cancer