Design Parameters and Human Biocompatibility Assessment Protocols for Organic Semiconducting Neural Interfaces: Toward a Printed Artificial Retina with Color Vision

• Published in: Advanced materials interfaces Vol. 10; no. 19
• Main Authors: Sherwood, Connor P., Crovador, Rafael, Posar, Jessie A., Brichta, Nathan, Simunovic, Matthew P., Louie, Fiona, Dastoor, Paul C., Brichta, Alan M., Cairney, Julie M., Holmes, Natalie P., Lim, Rebecca, Griffith, Matthew J.
• Format: Journal Article
• Language: English
• Published: Weinheim John Wiley & Sons, Inc 01.07.2023; Wiley-VCH
• Subjects: artificial retina; Biocompatibility; bioelectronics; Cell culture; Color vision; Design parameters; Elongation; Materials science; Mechanical properties; Morphology; Neural prostheses; neuroengineering; Optoelectronics; organic semiconductor; Organic semiconductors; printed electronics; Retina; Retinal cells; Semiconductor materials; Semiconductors
• ISSN: 2196-7350; 2196-7350
• DOI: 10.1002/admi.202202229

Organic semiconductors have emerged as promising neural interfacing materials due to their innate biocompatibility, soft mechanical properties, and mixed electron/ion conduction. One exciting application is their use as artificial photosensors for retinal prostheses via optically induced neuromodulation. In this study, the optoelectronic and neural interfacing properties of six organic semiconductor polymers and small molecules, split into donor/acceptor pairs that form promising candidates for a trichromatic artificial retina that closely mimics the native response of the human eye are presented. The biocompatibility of these materials using primary human retinal cell cultures by systematic measurement of both cell viability and morphological analysis of retinal ganglion cell neurite elongation over time is investigated. Comparable cell viability between human retinal cell cultures established on all the organic semiconductors and a glass control, which is a standard measurement for biocompatibility in materials science is observed. In contrast, differences in the morphological biocompatibility between the organic semiconductor materials and glass control are detected by analyzing neurite elongation with specific immunomarkers. The difference in the two results has implications for the future assessment of material biocompatibility for bioelectronics, and optimal methodology for assessing morphological biocompatibility in neural interface devices is discussed. This work establishes new materials design rules for printable organic semiconducting neural interfaces and demonstrates the importance of assessing both anatomical and functional biocompatibility with application‐specific neural tissue. The results are presented in the context of an artificial retina capable of optical neuromodulation to mimic color vision, though are generally applicable to other neural interfacing applications.