Preparation,characterization, and DNA interaction studies of cationic europium luminescent copolymer

This paper proposed a simple synthetic strategy towards a novel cationic europium luminescent copolymer, poly(METAC-co-NIPAm-co-Eu(AA)₃Phen) (PMNEu), and investigation about their complexation ability with DNA. In this approach, first, Eu(AA)₃Phen complex monomer containing Eu³⁺, acrylic acid (AA), and 1,10-phenanthroline (Phen) was synthesized, and subsequently, free radical copolymerization of Eu(AA)₃Phen complex monomer with other two functional monomers, 2-(methacryloyloxy) ethyl] trimethylammonium chloride (METAC) and N-isopropylarylamide (NIPAm), was carried out in methanol using azodiisobutyronitrile (AIBN) as the initiator. ¹HNMR, GPC, fluorescence spectroscopy, UV–vis spectroscopy, and TEM were used to investigate the chemical structures, molecular weight and molecular weight distribution, fluorescence properties, UV spectra, and morphologies of PMNEu copolymer, respectively. Furthermore, the interaction of PMNEu with DNA was also studied with fluorescence spectroscopy, UV–vis spectroscopy, and agarose gel electrophoresis. These results indicated that PMNEu could interact with DNA via an electrostatic bonding mode and the bonding constant was 2.2 × 10⁵ L/mol. Additionally, TEM observation showed that pure PMNEu formed micelles in water solution, while the size-controllable aggregations of PMNEu with DNA were obtained when PMNEu was mixed with DNA at various concentration ratios. A good biocompability of PMNEu was demonstrated through in vitro cytotoxicity assays.