Protection and delivery of probiotics by degraded fucoidan-chitosan nanogel-based W1/O/W2 double emulsion incorporated in self-assembled hydrogel particles

Probiotics as pharmaceutical and nutraceutical products are essential to human health, whereas maintaining their viability in adverse environments remains an obstacle. This study presents a well-designed W 1 /O/W 2 emulsion system incorporated in calcium-alginate hydrogel particles for the targeted delivery and sustained release of Lactobacillus bulgaricus in the gastrointestinal tract. Firstly, the degraded fucoidan (DF) with the highest carboxyl content (2.99%), prepared using UV/H 2 O 2 treatment, was more favorable for forming DF-CS nanogel through ionic cross-linking with chitosan (CS). The W 1 /O/W 2 double emulsion fabricated by 0.4 mg/mL DF-CS nanogel possessed the highest interface stability, as concluded from visual appearance, confocal laser scanning microscope (CLSM), droplet size distribution, and ζ-potential results. The double emulsion loaded in 2% alginate hydrogel showed desirable textural properties and swelling behavior, thereby offering a high encapsulation efficiency of Lactobacillus bulgaricus (74.5%). Additionally, the hydrogel delivery system not only achieved sustained release of Lactobacillus bulgaricus in the simulated gastrointestinal condition (>10 7  CFU/g) but also maintained at least 71.3% and 55.1% survival of probiotics at −20 °C and 4 °C, respectively, after 28 d of long-term storage. Overall, these W 1 /O/W 2 double emulsion-filled multilayer self-assembled hydrogel particles can be utilized for better protection and delivery of probiotics in the food and pharmaceutical industries.