Cyclodextrin-Based Polyrotaxanes and Polypseudorotaxanes as Drug Delivery Carriers

Cyclodextrins (CyDs) include linear polymers such as polyethylene glycol (PEG), polypropylene glycol (PPG) and polyethyleneimine (PEI) and spontaneously form supramolecular inclusion complexes, namely polypseudorotaxanes. When both ends of the polymer chains in polypseudorotaxanes are covalently capped with bulky molecules, CyDs are trapped in and cannot be dethreaded from the assembly, giving the so-called polyrotaxane. Recently, a large number of drug carriers based on polyrotaxanes and polypseudorotaxanes have been developed for various drugs, i.e., low molecular weight drugs, protein drugs, gene drugs and nucleic acid drugs. In this review, we introduce various applications of polyrotaxanes and polypseudorotaxanes as drug delivery techniques such as drug absorption, controlled release and drug targeting for various drugs.