Impact of sterilization on a conjugated polymer based bioelectronic patch

Translation into the clinic of organic bioelectronic devices having conjugated polymers as the active material will hinge on their long-term operation in vivo. This will require the device to be subject to clinically approved sterilization techniques without a deterioration in its physical and electronic properties. To date, there remains a gap in the literature addressing the impact of this critical pre-operative 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 non-uniform crosslinking caused by the 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, as well as inducing a minimal immune response as revealed by a receding fibrotic capsule after 4 weeks implantation. Our findings pave the way towards closing the gap for the translation of organic bioelectronic devices from acute to long-term in vivo models.