Characterization of Polyampholyte Comb-Type Copolymer DNA Carriers

The authors have reported several comb-type copolymers, consisting of a polycation backbone such as poly-L-lysine (PLL) and hydrophilic side chains of polysaccharides, for controling the assembling structure of DNA-copolymer complexes (1 –3 ). The DNA-copolymer system consists of two phases: compacted DNA-polycation complex and highly hydrated glycocalyx. The latter plays multiple roles in reducing the aggregation of the resulting complexes and increasing the solubility of the complexes (2 –3 ). Furthermore, the grafting degree of the copolymer affects the DNA conformation in the complex, permitting regulation of DNA compaction. The comb-type copolymers with a higher degree of grafting induce little compaction of DNA and stabilize DNA duplexes and triplexes by shielding the repulsion between phosphate anions of DNA. The grafting chains also reduce the nonspecific interaction of the PLL backbone with proteins.