Impact of Sterilization on a Conjugated Polymer-Based Bioelectronic Patch

Organic bioelectronics based on conjugated polymers as the active electronic material have been shown to operate efficiently at the biointerface. Their translation into a commercial medical device will hinge on their long-term operation in vivo. This will require the device to be subjected to clinically approved sterilization techniques without deterioration in its physical and electronic properties. To date, there remains a gap in the literature addressing the impact of this critical preoperative procedure on the properties of conjugated polymers. This study aims to address this gap by assessing the physical and electronic properties of a sterilized porous bioelectronic patch having polyaniline as the conjugated polymer. The patch was sterilized by autoclave, ethylene oxide, and gamma (γ-) irradiation at 15, 25, and 50 kGy doses. Autoclaving resulted in cracking and macroscopic degradation of the patch, while patches sterilized by γ-irradiation at 50 kGy exhibited reduced mechanical and electronic properties, attributed to chain scission and nonuniform cross-linking caused by high dose irradiation. Ethylene oxide and γ-irradiation at 15 and 25 kGy sterilization appeared to be the most effective at maintaining the mechanical and electronic properties of the patch and inducing a minimal immune response as revealed by a receding fibrotic capsule after 4 week implantation. Our findings pave the way toward closing the gap for the translation of organic bioelectronic devices from acute to long-term in vivo models.