Competitive reactions in dendriplex and polyplex solutions

Interaction of DNA with cationic poly(phenylenepyridinium) dendrimer or quaternized chitosan yielding formation of dendriplex and polyplex, respectively was studied by fluorescence quenching techniques. Factors of fine control over ternary systems wherein DNA and a synthetic polyanion compete for binding with the cationic compound were established. The dendrimer was displaced from the dendriplex by poly(styrenesulfonate) anion regardless pH or chains length even though rather short oligomer was used. By contrast, poly(methacrylate) anion (PMAA) was inert in slightly acidic media, whereas at neutral pH the displacement occurred and enhanced with PMAA lengthening. The revealed inability of PMAA to compete with DNA in slightly acidic solutions despite the pronounced stabilization of PMAA/dendrimer complex by H-bonds strongly suggests the key role of electrostatic interactions in the ternary systems with mixed type of the interaction. The analogous trends were ascertained on studying the polyplex solutions. The results of the investigation guide the way to improvements in design of efficient vectors for transfection.