Fucoidan-ovalbumin protein-based complex coacervates: preparation, characterization, and encapsulation of fucoxanthin

Ovalbumin-fucoidan (OF) complex nanoparticles were prepared for fucoxanthin encapsulation. The effects of polymer ratios (ovalbumin:fucoidan, 5:1, 2.5:1, 1:1, 1:2.5, 1:5 w/w) and pH values (3, 4.5, 6, 7, and 8) on complex coacervate formation were investigated to identify optimal conditions. The selected conditions were then applied for fucoxanthin encapsulation.

The OF complex exhibited particle sizes of 200-265 nm. The zeta potentials were -24.67 ± 0.42 mV for fucoidan, -17.25 ± 0.39 mV for ovalbumin, and -3.47 ± 0.90 mV for the OF complex. At pH 3, the zeta potentials of fucoidan and ovalbumin were -9.80 ± 0.30 mV and 7.33 ± 0.21 mV, respectively, confirming electrostatic interactions between the oppositely charged polymers and the formation of complex coacervates. Turbidity measurements indicated that a 1:1 polymer ratio (ovalbumin:fucoidan, w/w) at pH 3 was optimal for complex formation (P < 0.05), and these conditions were selected for fucoxanthin encapsulation. The resulting nanoparticles achieved 88.33 ± 0.14% encapsulation efficiency, and the chemical and morphological characteristics of the polymers and coacervates reflected changes due to interactions and fucoxanthin incorporation. Fucoxanthin release reached 12.83 ± 0.12% in simulated gastric fluid (SGF) and 42.77 ± 0.4% in simulated intestinal fluid (SIF).

This study suggests that OF complex nanoparticles are effective carrier for the encapsulation of hydrophobic compounds. © 2025 Society of Chemical Industry.