Development of a supramolecular nanocarrier for gene delivery based on cationic block copolymers

5 Conclusions: In this chapter, recent trends in the development of supramolecular nanocarriers of genes and related compounds, based on cationic copolymers, was highlighted. PEG is widely used as the non-ionic and hydrophilic parts of these non-viral gene carriers, as it has been approved by the FDA for use in pharmaceutical formulations. The PEGylation of proteins and peptide drugs has led to an improvement of their pharmacokinetics, proving the validity of using PEG to improve drug efficacy. Similarly, it is expected that PEGylation of gene carriers offers great promise for their optimization. Recent progress in the development of novel synthetic backbones for various kinds of PEG conjugates as well as preparation procedures for sophisticated polyplexes further extend the applicability of PEGylated gene carriers. PEG conjugates possessing moieties that are responsive to changes in their chemical and biological environment act as environmentally responsive polyplexes that can release therapeutic genes in response to external stimuli. Surface modification of polyplexes using ligands attached to the distal end of the PEG segment significantly enhances the internalization efficiency of polyplexes into the cytoplasm. In addition, various functional counterparts to the PEG segment are also available due to the recent development of regulated polymerization techniques. Currently, numerous studies are focusing on polyplex-based PEG-polycation copolymers with respect to their safety and gene transfection efficiency. Investigations of block- and graft-copolymer-based gene delivery systems have progressed rapidly, and is expected to lead to progress in engineered syntheses of PEG-based block and graft copolymers.