Formation of DNA complexes with diblock copolymers of poly(N-(2-hydroxypropyl)methacrylamide) and polycations

The self-assembly of calf thymus DNA with diblock copolymers of poly(N-(2-hydroxypropyl)methacrylamide) (HPMA) and polycations (PC) with amino or quaternary ammonium groups in their side chains was tested by static and dynamic light scattering methods in aqueous 0.15 M NaCl. We have observed formation of well defined clusters of single DNA interpolyelectrolyte complexes with hydrodynamic radii of about 300 nm. Long-term size stability of clusters has been found to be a function of chemical structure of PC and of diblock copolymer composition. The most stable clusters were obtained by DNA association with diblock copolymers consisting of a poly(HPMA) block (A) and polycation block (B) with quaternary ammonium groups in their side chains, with molecular weight of A block higher than that of B. In the opposite case, lower molecular weight of A block, slow aggregation of SIPEC clusters was observed. The micelle-like structure was proposed for these clusters. (C) 1998 Elsevier Science Limited.