Sodium Alginate–Benzene Sulfonate Ether: Synthesis, Behavior in Aqueous Solutions, and Anticoagulant Activity

The functionalization of alginate through the introduction of sulfonate groups represents a promising strategy for the targeted improvement of its bioactive characteristics. In this study, novel alginic acid derivatives modified with benzene sulfonate groups were synthesized in an aqueous alkaline medium, achieving a degree of substitution up to 0.51. The chemical structures of the obtained ethers were confirmed by NMR, FTIR, and UV spectroscopy. The effects of pH and ionic strength on the size of macromolecular aggregates in aqueous solutions were investigated using dynamic and electrophoretic light scattering techniques. Potentiometric titration results revealed enhanced intra- and intermolecular interactions correlating with increasing degrees of substitution. Furthermore, the anticoagulant activity of the modified alginates was assessed, demonstrating a significant prolongation of blood and plasma coagulation times.