Suitability of EtO Sterilization for Polydopamine-coated, Self-fitting Bone Scaffolds

Irregularly shaped craniomaxillofacial (CMF) defects may be advantageously treated by "self-fitting" shape memory polymer (SMP) scaffolds, namely those prepared from poly(ε-caprolactone)diacrylate (PCL-DA) networks and PCL-DA/poly(L-lactic acid) (PLLA) (75:25 wt%) semi-interpenetrating polymer networks (semi-IPNs). In addition to achieving good scaffold-tissue contact, a polydopamine (PD) coating can be leveraged to enhance bioactivity for improved osseointegration. Sterilization with ethylene oxide (EtO) represents a logical choice due to its low operating temperature and humidity. Herein, for the first time, the impact of EtO sterilization on the material properties of PD-coated SMP scaffolds was systematically assessed. Morphological features (i.e., pore size and pore interconnectivity), and in vitro bioactivity were preserved as were PCL crystallinity, PLLA crystallinity, and crosslinking. These latter features led to sustained shape memory properties, and compressive modulus. EtO-sterilized, PD-coated scaffolds displayed similar in vitro degradation behaviors versus analogous non-sterilized scaffolds. This included maintenance of compression modulus following 28 days of exposure to non-accelerated degradation conditions.