Micellar Nanogels\nfrom Alginate-Based Diblock Copolysaccharides

Alginates are marine polysaccharides known for their\nability to\nselectively bind calcium ions and form hydrogels. They are widely\nused in biomedical applications but are challenging to produce as\nnanogels. Here we introduce a self-assembly route to create stable\nalginate-based nanogels under near-equilibrium conditions. Guluronate\n(G) blocks, which interact with divalent cations such as Ca<sup>2+</sup>, Ba<sup>2+</sup>, and Sr<sup>2+</sup>, were extracted from alginates\nand covalently linked through their reducing end to the reducing end\nof dextran (Dex) chains, forming linear block copolymers that self-assemble\ninto micellar nanogels with a core-corona structure in the presence\nof these ions. Real-time dynamic light scattering (DLS) and small-angle\nneutron scattering (SANS) were used to study the self-assembly mechanism\nof the copolymer during dialysis against divalent ions. For the G<sub>12</sub>-<i>b</i>-Dex<sub>51</sub> copolymer, we achieved\nspherical micelles with an 8 nm radius and an aggregation number of\naround 20. Although the type of divalent cation affected micelle stability,\nit did not influence their size. Micellar nanogels are dynamic structures,\ncapable of ion exchange, and can disassemble with chelating agents\nlike ethylenediamine tetraacetic acid (EDTA).