Carbon fiber reinforced polymers for implantable medical devices

Carbon fibers reinforced polymers (CFRPs) are prolifically finding applications in the medical field, moving beyond the aerospace and automotive industries. Owing to its high strength-to-weight ratio, lightness and radiolucency, CFRP-based materials are emerging to replace traditional metal-based medical implants. Numerous types of polymers matrices can be incorporated with carbon fiber using various manufacturing methods, creating composites with distinct properties. Thus, prior to biomedical application, comprehensive evaluation of material properties, biocompatibility and safety are of paramount importance. In this study, we systematically evaluated a series of novel CFRPs, aiming at analyzing biocompatibility for future development into medical implants or implantable drug delivery systems. These CFRPs were produced either via Carbon Fiber-Sheet Molding Compound or Fused Deposition Modelling-based additive manufacturing. Unlike conventional methods, both fabrication processes afford high production rates in a time-and cost-effective manner. Importantly, they offer rapid prototyping and customization in view of personalized medical devices. Here, we investigate the physicochemical and surface properties, material mutagenicity or cytotoxicity of 20 CFRPs, inclusive of 2 surface finishes, as well as acute and sub-chronic toxicity in mice and rabbits, respectively. We demonstrate that despite moderate in vitro physicochemical and surface changes over time, most of the CFRPs were non-mutagenic and non-cytotoxic, as well as biocompatible in small animal models. Future work will entail extensive material assessment in the context of orthopedic applications such as evaluating potential for osseointegration, and a chronic toxicity study in a larger animal model, pigs.