Abstract
This study investigates the feasibility and therapeutic effectiveness of a novel drug‑loaded parylene electrode prototype (PEP) designed to reduce inflammation and hearing loss associated with cochlear implantation (CI). The porous PEP was fabricated using vapor‑phase sublimation and deposition, producing an interconnected structure with 20-30 µm pores and mechanical flexibility suitable for intracochlear placement. Dexamethasone was incorporated into the device (Dex/PEP), and in vitro characterization using ELISA and spectrophotometry demonstrated controlled first‑order release kinetics. Guinea pigs underwent microsurgical implantation of PEPs, with accurate positioning confirmed by micro‑CT imaging. Auditory outcomes were assessed through auditory brainstem response (ABR) measurements, and cochlear tissues were examined histologically to evaluate inflammatory cell infiltration and cytokine expression. The Dex/PEP device exhibited biosafety comparable to traditional silicone electrodes and provided sustained drug release. Animals receiving Dex/PEP showed significantly improved ABR thresholds at 1 and 4 weeks compared with blank PEP controls (p < 0.05), indicating reduced inflammation‑induced hearing loss. Histological analysis further revealed diminished inflammatory cell infiltration and markedly decreased TNF‑α expression at the round window membrane (p = 0.001). These findings support the drug‑loaded PEP as a promising targeted delivery platform for reducing cochlear inflammation and preserving hearing following CI.