Three-dimensional magnetic fibrous scaffold with icariin expanded by supercritical CO₂ for bone tissue engineering under static magnetic field

The electrospun fibrous scaffold has shown a great potential due to an extracellular matrix-mimicking structure of nanofibers, however, a three-dimensional (3D) fibrous scaffold, much similar to in vivo environment, still remains challenging in fabrication. The magnetic nanoparticles (MNPs) have been explored to promote bone-related cells activity under static magnetic field (SMF). Herein, via electrospinning, Fe₃O₄ MNPs and icariin (ICA) from traditional Chinese medicine were introduced into polycaprolactone (PCL) fibers to manufacture two-dimensional (2D) membranes (PCL/Fe₃O₄/ICA), which were then expanded to 3D scaffold by depressurization of subcritical CO₂ fluid. The expanding behavior was more remarkable for the membrane collected from rotary collector than that on plate collector, especially after the addition of Fe₃O₄ MNPs. Co-cultured with pre-osteoblasts, PCL/Fe₃O₄/ICA 3D scaffold induced a higher cell proliferation viability than that in 2D membrane in later period, and the combined utilization with SMF group showed the highest cell viability. When implanted subcutaneously, 3D scaffold exhibited better cell infiltration, internal collagen deposition and angiogenesis due to the enhanced porosity and the action of ICA. This highly porous magnetic PCL/Fe₃O₄/ICA 3D scaffold provided a new idea for the design and application of magnetic scaffold in the bone tissue engineering.