Radiopaque Implantable Biomaterials for Nerve Repair

Repairing peripheral nerve injuries remains a clinical challenge. To enhance nerve regeneration and functional recovery, the use of auxiliary implantable biomaterial conduits has become widespread. After implantation, there is currently no way to assess the location or function of polymeric biomedical devices, as they cannot be easily differentiated from surrounding tissue using clinical imaging modalities. Adding nanoparticle contrast agents into polymer matrices can introduce radiopacity and enable imaging using computed tomography (CT), but radiopacity must be balanced with changes in material properties that impact device function and biological response. In this study radiopacity was introduced to porous films of polycaprolactone (PCL) and poly(lactide-co-glycolide) (PLGA) 50:50 and 85:15 with 0-40wt% biocompatible tantalum oxide (TaO x ) nanoparticles. To achieve radiopacity, at least 5wt% TaO x was required, with ≥ 20wt% TaO x leading to reduced mechanical properties and increased nano-scale surface roughness of films. As polymers used for peripheral nerve injury devices, films facilitated nerve regeneration in an in vitro co-culture model of glia (Schwann cells) and dorsal root ganglion neurons (DRG), measured by expression markers for myelination. The ability of radiopaque films to support nerve regeneration was determined by the properties of the polymer matrix, with a range of 5-20wt% TaO x balancing both imaging functionality with biological response and proving that in situ monitoring of nerve repair devices is feasible.