Polyanions and their complexes. Part V. Examination of polyanion–cation interaction using pulse radiolysis

Abstract

Changes in e^–_aq reaction rate with methylene blue and acridine orange, following the addition of polyanion, demonstrate that interaction occurs in aqueous solution between these metachromatic dyes and hyaluronic acid, sodium poly(ethylenesulphonate), sodium poly(styrenesulphonate), heparin, and DNA. The changes are reversed on addition of sodium chloride and methanol and increase in temperature, which are known to destroy the interaction and reverse the metachromatic shift. Interaction can also be demonstrated with methyl green, which is a non-metachromatic dye.

The method is extended to study the interaction between cetyl pyridinium chloride, the polycations polylysine and protamine sulphate, and the polyanions HEP and DNA before electrochemical equivalence and consequently precipitation occurs. Ion-binding due to the formation of contact ion-pairs, formed unusually in water as a result of the high electrostatic potential on the surface of the macroion, adequately accounts for the results.