Mucoadhesive polydopamine-coated nanoparticle-mediated inner ear drug delivery for hearing loss treatment

This study investigated the potential of mucoadhesive polymeric nanoparticles coated with polydopamine (Dopa-NPs) for inner ear drug delivery. Dopa, inspired by mussel adhesion proteins, leveraged the mucoadhesive properties of NPs and enhanced their retention within the cochlea. Dopa-NPs were compared with non-adhesive uncoated control NPs to reveal their safety and drug delivery efficiency. The safety evaluation demonstrated no toxicity during in vitro test using HEI-OC1 cells and in vivo test using mouse with auditory function assessment. When coumarin-encapsulated NPs were administered through intratympanic injection to mice, Dopa-NPs provided intense fluorescence in the inner ear compared to non-adhesive control NPs. Furthermore, dexamethasone (Dex)-encapsulated Dopa-NPs exhibited significantly higher drug concentrations in the cochlea than dexamethasone sodium phosphate and uncoated NPs. Finally, in vivo test using an ototoxicity-induced animal model showed that Dopa-NPs improved hearing protection, as indicated by the auditory brainstem response (ABR) test. In conclusion, mucoadhesive Dopa-NPs exhibit enhanced drug delivery efficiency and safety, offering a promising strategy for inner ear drug delivery and chemotherapy.