Targeted drug delivery system (TDDS) nowadays has been adopted as a superb approach to the therapies of cancer and other mortal diseases. Cyclodextrins (CDs) are chosen to take the part of a promising drug carrier due to its low toxicity and high flexibility of structure modification. They are commonly used to enhance the aqueous solubility, chemical stability, safety and bioavailability of drugs in virtue of their peculiar ability to form CD/drug inclusion complexes. Not only native and chemically modified cyclodextrins were employed as drug carriers, but also sorts of CD-based more sophisticated carrier systems such as polyrotaxanes/polypseudorotaxanes, polycations and nanoparticles emerged in recent years. Considering the fact that lots of biological receptors such as folate receptor, asialoglycoprotein receptor, hyaluronic receptor, transferrin receptor, integrin receptor are overexpressed on the surface of most cancer cells and other focal cells, design of TDDS containing matching targeting ligands (TLs) could help realize targeted therapy for those focal cells or tissues. Targeting ligands such as folic acid (FA), mono- and oligosaccharides, hyaluronic acid (HA), transferrin, RGD sequence are consequently chemically bound to CD-based carriers to form targeted carrier systems which further furnished TDDS via non-covalent complexation or bio-cleavable conjugation to drug molecules. Such TDDS are also widely applied on nucleic acid delivery in addition to chemotherapeutical drugs. As to depict the important developments, basic targeting principles and the latest progress on targeted drug delivery systems based on CDs are summarized, and also a brief prospect is given in this review.

Contents
1 Introduction
2 Folate receptor-mediated TDDS based on CDs
2.1 Targeting mechanism
2.2 Progress on folate receptor-mediated TDDS based on CDs
3 Asialoglycoprotein receptor-mediated TDDS based on CDs
3.1 Targeting mechanism
3.2 Progress on asialoglycoprotein receptor-mediated TDDS based on CDs
4 Hyaluronic receptor-mediated TDDS based on CDs
4.1 Targeting mechanism
4.2 Progress on hyaluronic receptor-mediated TDDS based on CDs
5 Transferrin receptor-mediated TDDS based on CDs
5.1 Targeting mechanism
5.2 Progress on transferrin receptor-mediated TDDS based on CDs
6 Integrin receptor-mediated TDDS based on CDs
6.1 Targeting mechanism
6.2 Progress on integrin receptor-mediated TDDS based on CDs
7 Other receptor-mediated TDDS based on CDs
8 Conclusion