A Cationic Smart Copolymer for DNA Binding

A new block copolymer with a temperature-responsive block and a cationic block was prepared by reversible addition-fragmentation chain transfer (RAFT) polymerization, with good control of its size and composition. The first block is composed by di(ethylene glycol) methyl ether methacrylate (DEGMA) and oligo(ethylene glycol) methyl ether methacrylate (OEGMA), with the ratio DEGMA/OEGMA being used to choose the volume phase transition temperature of the polymer in water, tunable from ca. 25 to above 90 degrees C. The second block, of trimethyl-2-methacroyloxyethylammonium chloride (TMEC), is positively charged at physiological pH values and is used for DNA binding. The coacervate complexes between the block copolymer and a model single strand DNA are characterized by fluorescence correlation spectroscopy and fluorescence spectroscopy. The new materials offer good prospects for biomedical application, for example in controlled gene delivery.