Electroactive Nanocomposite Porous Scaffolds of PAP n /op-HA/PLGA Enhance Osteogenesis in Vivo.

The three-dimensional (3D) porous nanocomposite biomimic scaffolds with electroactivity and bioactivity were prepared as bone implants by a freeze-drying method using 1,4-dioxane as a solvent. The multiblock copolymer (PAP n ) was synthesized by the condensation polymerization of hydroxyl-capped poly(lactide)(PLA) and carboxyl-capped aniline pentamer (AP), which were introduced as electroactive functional polymers. A bioactive component, hydroxyapatite (HA) grafting l-lactic acid oligomer (op-HA), showed a better interface compatibility with PAP n and poly(lactide- co -glycolide) (PLGA). Honeycomb-like and interconnected porous structures could be obtained as displayed by scanning electron microscopy (SEM). The intramuscular implants showed a good biocompatibility and higher osteogenetic activity by promoting cell ingrowth and collagen fibers forming as indicated by SEM, hematoxylin-eosin (H&E) staining, and Masson's trichrome staining. Implantation for the repair of rabbit radius defects under 5 V at 100 Hz with a 50% duty cycle for 30 min every other day was evaluated, and sheep tibia defects were also carried out. The composite scaffold with 1 wt % PAP n exhibited better behaviors, such as a distinct bone callus, bridging growth, vague borderlines between newly formed bone at the two defect ends, and increased bone density as indicated by radiographic images and micro-computed tomography (Micro-CT) images. Electricity stimulation could significantly accelerate the healing of a fracture. All in all, the stimuli-responsive electroactive nanocomposites showed a potential application in bone tissue engineering.