Hydrophobic Derivatization of Sodium Alginate for Use in Fucoxanthin Delivery

The present study successfully devised an innovative pH-sensitive system for encapsulating fucoxanthin, which effectively shielded RAW 264.7 cells from H 2 O 2 -induced damage. The formulation requires modification of sodium alginate with octanoyl chloride (C8) via esterification to provide amphiphilic self-assembly capacity of the system and loading of fucoxanthin via sonication. The hydration diameter (193.9 - 167.9 nm) and critical aggregation concentration of the micellar-like aggregates (1.4 - 0.5 mg/mL) gradually decreased with the increasing degree of substitution (1.54% - 60.20%). The encapsulation efficiency (46.11% - 88.54%) and loading capacity (4.61% - 8.85%) showed a positive correlation with the increasing degree of substitution. The TEM confirmed complete fucoxanthin encapsulation in micellar-like aggregates, forming smooth-surfaced spherical particles. In vitro simulated digestion assays demonstrated that micellar-like aggregates effectively shielded fucoxanthin from premature gastric release, while significantly improving its release efficiency during the intestinal phase. Fucoxanthin-loaded micellar-like aggregates endocytosed by RAW 264.7 cells alleviated cellular oxidative stress damage by reducing ROS levels. The study demonstrates the potential of self-assembled sodium alginate nanoparticles as a novel carrier for efficient delivery of hydrophobic substances, thereby establishing an innovative formulation for alleviating oxidative stress.