Förster Resonance Energy Transfer (FRET) Demonstrates In Vitro Chitosan-Coated Nanocapsules Suitability for Intranasal Brain Delivery

Intranasal drug delivery to the brain offers a promising strategy to overcome biological barriers. Chitosan-coated nanoemulsion-based nanocapsules demonstrate significant potential due to their mucoadhesive properties, ability to permeate epithelial cells, and ability to solubilize poorly water-soluble drugs, making them ideal candidates for bypassing the blood-brain barrier and overcoming the nasal mucosa. To ensure effective drug delivery, it is critical to assess the integrity of these nanocapsules during their transit across such barriers. In this study, we employed Förster resonance energy transfer to track the structural integrity of nanocapsules during transport. A simplified in vitro model was established using Calu-3 cells to mimic the mucosal epithelial barrier and Balb-c 3T3 fibroblasts as target cells. Our findings demonstrated that the nanoemulsion core of the nanocapsules successfully crossed the in vitro epithelial barrier and reached target cells while maintaining its structural integrity. These results validate the potential of chitosan-coated nanocapsules as a robust platform for the intranasal delivery of drugs to the brain.