Degradable polymers as tools for polyelectrolyte complex analysis

As part of our investigations of the interest in degradable artificial biopolymers, attention was recently paid to other applications such as analysis of polyelectrolyte complexes or release of one of their polyelectrolyte component. The present work is aimed at comparing the enzymatic degradation of polyelectrolyte complexes formed when polyanions made of similar building blocks but having different chemical structures and charge densities are mixed with an enzyme sensitive polycation, namely poly(L-lysine). The two selected polyanions were poly(L-lysine citramide) and poly(L-lysine citramide imide) and the selected enzyme was trypsin. Fractions were prepared at different values of the degree of neutralization by adding the polycation in solution to a polyanion solution and vice-versa, according to a titration protocol. Dynamic light scattering was used to assess the size and stability of the complexes in the presence of salt at various concentrations. The molecular dimensions of the fractionated polyanions recovered after the degradation of the associated polycation molecules were determined by size exclusion chromatography. The influence of the chemical structure and charge density were discussed and the influence of the order of addition of the oppositely charged complex precursors was also discussed.