Functionalized Cochlear Implant Electrode for Intracochlear Histamine Detection via Molecularly Imprinted Polymer Coating

By coating the electrodes of a cochlear implant (CI) electrode array with a powdered form of molecularly imprinted polymer (MIP), a straightforward process to functionalize existing electrodes to selectively detect histamine is demonstrated. Detection is based on non-Faradaic impedance spectroscopy, omitting the need for a reference electrode or redox mediators, and fitting to a 5-element equivalent electronic circuit. Proof-of-concept measurements on three functionalized cochlear implants in three human cadaveric cochleae indicate a level of detection of 200 nM of histamine in albumin-based artificial perilymph following a sigmoid dose-response trend up to 10 mM. This sensitivity enables quantized and localized analysis of histamine-mediated inflammation immediately following the CI operation. The selectivity and adaptability of MIPs opens possibilities to detect a wide spectrum of inflammation markers inside the human cochlea and could be used for fast mid- or postoperative intervention to improve the medical implant's outcome. Real-time monitoring of inflammation inside the hearing organ is difficult due to the restrictive geometry and small quantity of fluid. Herein, histamine sensor functionalization of three cochlear implants is demonstrated, tested in human cadaveric cochleae. A level of detection of 200 nanomolar of histamine, sufficient to quantify inflammation, is demonstrated using a non-Faradaic impedimetric approach without redox mediators or reference electrode.image (c) 2023 WILEY-VCH GmbH