Investigating the Influence of Phosphate Ions on Poly(l‑lysine) Conformations by Taylor Dispersion Analysis

In this work, the influence of the ionic strength and phosphate ions on poly­(l-lysine) hydrodynamic radius, conformation and persistence lengths has been studied for molar masses comprised between 3000 and 70 000 g/mol. Mark–Houwink coefficients have been obtained via the determination of poly­(l-lysine) hydrodynamic radius using Taylor dispersion analysis. The influence of phosphate ions and ionic strength on the solvent quality (poor, Θ, or good solvent) for poly­(l-lysine) have been studied in details. Quantitative data on hydrodynamic radius, persistence length, Mark–Houwink coefficients are provided at pH 7.4, in the range of 10 mM to 1 M ionic strength, and for different phosphate ion concentrations from 0.1 mM to 50 mM under physiological conditions (154 mM ionic strength, pH 7.4). The strong influence of phosphate ions on poly­(l-lysine) properties was finally illustrated by studying the interactions (stoichiometry, binding constant, and cooperativity) between poly­(l-lysine) of DP 50 and human serum albumin, in the absence and in the presence of phosphate ions at pH 7.4

Effect of Dendrimer Generation on the Interactions between Human Serum Albumin and Dendrigraft Polylysines

This work aims at studying the interaction between human serum albumin and different generations of dendrigraft poly-l-lysine (DGL) in physiological conditions. The binding constants and stoichiometry of the interaction were successfully determined using frontal analysis continuous capillary electrophoresis. The effect of generation on the interaction was evaluated for the five first generations of DGL. An increase of the binding constant accompanied with a decrease of the HSA:DGL (1:<i>n</i>) stoichiometry and a decrease of the cooperativity with dendrimer generation was observed. These findings were in good agreement with the increase of ligand (DGL) size, the increase of electrostatic ligand–ligand repulsion, and the localization of two negatively charged interaction sites on the HSA. The effect of the ligand topology (linear vs dendrigraft) on the HSA interaction revealed that linear poly­(l-lysine) leads to much lower stoichiometry compared to DGL of similar molar mass due to much higher flexibility and contour length