Nasal Delivery of Phytochemicals Using Nanocarriers: Therapeutic Opportunities and Translational Challenges.

The integration of phytochemicals with nanotechnology represents a promising approach to enhance nasal drug delivery, improving therapeutic efficacy and targeted brain delivery. This review explores recent advances in phytochemical-nanotechnology formulations and their applications in managing neurodegenerative diseases, respiratory disorders, and cancers. Phytochemicals such as curcumin, resveratrol, and quercetin exhibit potent pharmacological properties but suffer from poor solubility and limited bioavailability. Nanotechnology-based systems-including nanoparticles, liposomes, and nanoemulsions-overcome these drawbacks by improving stability, absorption, and controlled release. However, challenges such as nasal mucosa irritation, formulation complexity, regulatory barriers, and scalability still impede clinical translation. Notably, encapsulation of curcumin in polymeric nanoparticles has been shown to enhance its solubility and bioavailability, producing improved therapeutic outcomes in preclinical Alzheimer's models. Overall, this review underscores the synergistic potential of phytochemicals and nanotechnology in developing innovative nasal delivery platforms capable of providing targeted, effective, and patient-friendly treatment options for a range of medical conditions.