Surfactant-assisted hierarchical assembly of debranched starch nanoparticles: Insights into desolvation-driven molecular and crystalline ordering.

This study elucidates how surfactant incorporation phase and process stage govern the hierarchical self-assembly of debranched starch (DBS) during nanoprecipitation. Using Tween 80 (TW 80) as a model surfactant, we demonstrated that restricting its incorporation to the anti-solvent (ethanol) phase prevents premature polymer sequestration, enabling instantaneous interfacial stabilization. Pyrene fluorescence spectroscopy and multiscale structural analyses identified the 10% (w/w) TW 80 formulation as the optimal formulation within the sub-T1 aggregation regime. Under this sub-T₁ aggregation condition, TW 80 promoted rapid desolvation-driven self-assembly, enabling DBS chains to form well-ordered, single-helical V-type inclusion matrices with a maximum complexing index of ∼87%. This optimized structural evolution yielded relatively uniform nanoparticles characterized by a minimum hydrodynamic diameter of 186 nm and a maximized zeta potential of -39 mV, and representative TEM observations were consistent with the DLS-derived particle-size and dispersion trends. Stage-resolved structural tracking revealed an asynchronous structural evolution, where rapid, local helical ordering strictly preceded global crystalline packing. Conversely, surpassing the T1 threshold (20% TW 80) triggered interfacial over-aggregation and less ordered A-type crystallization. Functionally, the optimized DBS nanoparticles exhibited high rutin encapsulation efficiency (∼80%), which decreased to ∼65% under surfactant over-aggregation conditions. These findings provide a strategic, quantitative framework for designing carbohydrate-based nanoscale delivery systems.