Controllable alkaline dissociation of anionic polysaccharides governs nano-coassembly with soy β-conglycinin: a rational design for intestinal-targeted delivery systems.

The structure-dependent interactions between proteins and polysaccharides are crucial for designing functional nanocomposites, yet the underlying mechanisms governing nanostructure formation under pH-shift remain underexplored. This study innovatively proposed that the controllable alkaline dissociation characteristics of anionic polysaccharides (sodium alginate (SA), κ-carrageenan (CS), pectin (PE)) were the core to regulate the structure and function of soy β-conglycinin (7S)-polysaccharide nanocomposites via a green pH-shift method. SA, with moderate charge density and alkali-induced chain dissociation, formed uniform core-shell nanoparticles (85.76 nm) via strong enthalpy-driven interactions, while high-charged CS (excessive chain entanglement) and branched PE (incomplete dissociation) induced heterogeneous aggregation (113.3-229.5 nm). The optimal SA/7S nanocomposites exhibited high curcumin encapsulation (87.28%), enhanced storage stability, and potential intestinal delivery of curcumin, with only 17.61% released in gastric conditions and a final bioavailability of 72.76% (4-fold higher than free curcumin). This work provides new insights into the structure-function relationship of polysaccharides in protein-based nano-delivery systems, offering a rational design strategy for intestine-targeted nutraceutical carriers in plant-based functional foods.