Mucoadhesive Nanoemulsion via Engineered Anionic Surfactant-Chitosan Interactions for Enhanced Delivery of Fucoxanthin

Fucoxanthin (FX) is a marine-derived carotenoid with strong antioxidant and neuroprotective potential, making it a promising candidate for Alzheimer’s disease therapy. However, its lipophilic nature and poor aqueous solubility limit its bioavailability. To reach the brain, FX must also overcome the blood-brain barrier (BBB). Intranasal administration offers a non-invasive route that can bypass the BBB, but  its success depends on a formulation that can protect FX and promote efficient nose-to-brain transport. This work focuses on designing a mucoadhesive nanoemulsion (NE) with potential for intranasal delivery of FX, by engineering interactions between an anionic surfactant and the cationic polymer, chitosan at the droplet interface to understand the influence of these interactions on mucoadhesion and colloidal stability.  To elucidate the role of interfacial charge dynamics, we use a combination of characterization techniques including UV-vis spectrophotometry, dynamic light scattering, electrophoretic mobility, and rheology. Initial complexation studies show that within a charge ratio range of 0.3–0.65, emulsions exhibit optimal colloidal stability and maintain relatively smaller droplet sizes around 600nm. These findings guide the preparation of NE systems and ongoing work is focused on optimizing formulation parameters and processing conditions to further reduce droplet size, improve NE stability and FX-NE encapsulation efficiency. Overall, this work advances the development of a nose-to-brain delivery platform for FX, offering a promising therapeutic approach for neurogenerative diseases.