Cyclodextrin based natural nanostructured carbohydrate polymers as effective non-viral siRNA delivery systems for cancer gene therapy.

Short interfering RNAs (siRNAs), as small non-coding RNA fragments, are one of the widely studied RNAi inducers for gene modulations. The reasonably designed siRNA probes provide a novel potential therapeutic strategy for cancer therapy via silencing the specific cancer-promoting gene. The optimization of physicochemical properties of delivery vectors, such as stability, the possibility of surface functionalization, size, charge, biocompatibility, biodegradability, and non-immunogenicity with receptor-mediated targeting ligands, is necessary for effective intracellular siRNA delivery. The present review is focused on the recent progress of the non-viral nanocarriers for siRNA cancer treatment based on synthetic approaches associated with cyclodextrin (CD)-based carbohydrate polymers, i.e. CD-cationic polymers, CD-polyrotaxanes, CD-dendrimers, and CD-modified tumor-specific targeting ligands. Besides, the efficiency of nanocarriers-based stimuli-responsive CDs is described for the simultaneous delivery of siRNAs and chemotherapeutic drugs. Further, theranostic CD compounds are introduced for the specific diagnosis and cargo-targeting delivery to the specific disease sites. In the meantime, the development of the inherent fluorescent CD-based supramolecular biomaterials without formal chromophores will open up a new strategy to design an effective theranostic non-viral carrier system.