PTEG, a novel polycation with strong proton-buffering capability in wide pH range: synthesis, proton-buffering capability source and colloidal complexes of DNA

A novel randomly branched polycation with good proton-buffering capability over a wide pH range (named PTEG) and its polyplexes with DNA were prepared and characterized by various techniques. Characterization via 1 H NMR, 13 C NMR, FTIR, TGA, DSC, element analysis and protonation titration showed the structure and physical, chemical properties of PTEG. Characterization via electrophoresis, dynamic light scattering, zeta potential analysis and AFM showed that PTEG and DNA formed colloidal complexes. The reason of strong proton-buffering capability below pH 7.4 (that is, proton sponge effect) of PTEG was deeply studied and the results showed that it had no relation with amino group kind. The real reason was series-wound coupled amino groups connected by two carbons, which provides a basis for the synthesis of cationic polymers with strong proton sponge effect.