Journal article
Development of zwitterionic hydrogel thin film coatings of cochlear implant electrode arrays that reduce intracochlear inflammation and electrode impedance
Hearing research, Vol.474, 109606
04/2026
DOI: 10.1016/j.heares.2026.109606
PMID: 41833188
Abstract
•Cochlear implantation leads to a robust intracochlear inflammatory response.•Zwitterionic hydrogel coatings minimize the foreign body response.•CIs were successfully coated with a thin film zwitterionic hydrogel coating.•Coated CIs yielded lower impedances, inflammation, and fibrosis in a sheep model.
Cochlear implants (CIs) have revolutionized the treatment of sensorineural hearing loss, yet patient outcomes remain highly variable due to biological responses within the cochlea. A critical challenge is the foreign body response (FBR) triggered by CI biomaterials, which can lead to inflammation, fibrosis, and increased electrode impedance, ultimately impairing auditory function. Zwitterionic hydrogels have been shown to provide a highly lubricious anti-fouling surface that minimizes protein and cell adsorption. This study evaluates a carboxybetaine methacrylate (CBMA) zwitterionic hydrogel coating to reduce the FBR to cochlear implants. Using a large animal (sheep) model, human CI electrode arrays were coated with a thin film CBMA hydrogel via one step UV photografting and photopolymerization with a custom mold. Electrophysiological measurements at the time of implantation demonstrate significantly reduced total impedance, polarization impedance, and access resistance in CBMA-coated CIs. Reductions in total impedance and access resistance were maintained after 4 weeks in vivo. High-resolution Xray Microscopy imaging confirmed intracochlear placement without translocation or tip fold-over and a trend to reduced neoossification in CBMA-coated implants. Histological analysis revealed significantly decreased cellular infiltration, macrophage infiltration, and fibrotic tissue deposition within the cochlea surrounding CBMA-coated implants compared to uncoated controls. This work highlights the potential of durable thin film zwitterionic coatings to enhance CI performance and preserve residual hearing by mitigating insertional trauma and attenuating chronic inflammation and fibrosis.
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Details
- Title: Subtitle
- Development of zwitterionic hydrogel thin film coatings of cochlear implant electrode arrays that reduce intracochlear inflammation and electrode impedance
- Creators
- Nir Ben-Shlomo - University of IowaAdreann Peel - University of IowaChristine Etler - University of IowaBrian Mostaert - University of IowaGeorge Barrera - University of IowaKameron R. Hansen - University of IowaBryce Hunger - University of IowaDouglas Fredericks - University of IowaC. Allan Guymon - University of IowaMarlan R. Hansen - University of Iowa
- Resource Type
- Journal article
- Publication Details
- Hearing research, Vol.474, 109606
- DOI
- 10.1016/j.heares.2026.109606
- PMID
- 41833188
- NLM abbreviation
- Hear Res
- ISSN
- 0378-5955
- eISSN
- 1878-5891
- Publisher
- Elsevier B.V
- Grant note
- Department of Radiology at The University of Iowa
The authors would like to acknowledge Protostudios for their assistance in manufacturing the custom molds for cochlear implant molding. We acknowledge University of Iowa Central Microscopy Research Facility for assistance with H&E staining and tissue preparation. We also acknowledge the use of the Small Animal Imaging Core Facility, a core resource supported by the Department of Radiology at The University of Iowa.
- Language
- English
- Electronic publication date
- 03/10/2026
- Date published
- 04/2026
- Academic Unit
- Molecular Physiology and Biophysics; Orthopedics and Rehabilitation; Craniofacial Anomalies Research Center; Chemical and Biochemical Engineering; Neurosurgery; Otolaryngology
- Record Identifier
- 9985144738202771
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