Abstract
Dexamethasone (DEX) is used to treat ocular surface diseases. However, regulating DEX duration in tears while preventing its absorption into the anterior chamber is critical for balancing its therapy effects and the side effects. In this study, a novel magnetic nanoparticle (MNP)-micelle (MC) co-delivery system (MMDS) was developed. The MC moiety in the MMDS served as the carrier for DEX and the MNP part endowed the MMDS with magnetic-responsive properties. To extend its residency, the MMDS was magnetically attracted by an external magnet after instilling, which acted as a precorneal drug-depot enabling a sustainable release of DEX in tears. With combination of magnet treatment, the topical instillation of MMDS@DEX significantly prolonged the DEX-retention in tears and increased the DEX-concentration in the cornea and conjunctiva, as well as concurrently reduced the DEX-level in the aqueous humor, when compared with the commercial DEX eye drop treatment. The combination of MMDS@DEX and magnet treatment exerted significantly better therapeutic effects against DED with smaller side effects than conventional treatments including DEX suspension, commercial DEX eye drops, as well as the MMDS@DEX treatment alone. The present work provided a new method for the effective delivery of DEX to ocular surface tissues while reducing its side effects, which will be beneficial to the treatments of a wide range of ocular surface diseases.