Fucoxanthin encapsulation in chitosan-carrageenan nanoparticles for improved stability and bioavailability

Fucoxanthin (FX), a bioactive carotenoid derived from Isochrysis galbana, exhibits significant therapeutic potential; however, its application is limited by poor physicochemical stability and low oral bioavailability. To overcome these limitations, FX-loaded chitosan-carrageenan nanoparticles (FX-CS/CRG-NPs) were developed via ionic complexation and optimized using a Box-Behnken design, with the CS:CRG ratio, Tween 80 concentration, and FX loading as independent variables. The optimized formulation (CS:CRG 1:0.12 w/w, 0.70% Tween 80, and 1 mg FX) yielded nanoparticles with a hydrodynamic diameter of 374 ± 19 nm, a zeta potential of +52.8 ± 1.0 mV, and an encapsulation efficiency (EE) of 85.2 ± 3.0%. Compared with free FX, the optimized nanoparticles exhibited significantly enhanced stability, retaining 21.51 ± 0.46% after 12 h at 60 °C and 40.51 ± 0.48% after 12 h of UV exposure, corresponding to 3.1- and 4.6-fold increases, respectively. During 60 days of storage, encapsulated FX retained 81.6 ± 1.37% at 4 °C and 24.69 ± 4.97% at 25 °C, whereas free FX showed markedly higher degradation. Simulated gastrointestinal digestion demonstrated improved stability and intestinal bioaccessibility, with recovery values of 82.86 ± 4.92% and 75.67 ± 2.96% for encapsulated FX, compared with 33.21 ± 5.43% and 29.36 ± 2.89% for free FX. In vivo, oral administration resulted in a 3.4-fold increase in plasma fucoxanthinol (FXOH) and a threefold increase in hepatic FXOH, indicating enhanced systemic exposure at the selected time point. Overall, CS/CRG nanoencapsulation significantly improves the stability and gastrointestinal performance of fucoxanthin, supporting its potential as an effective nanodelivery platform.