Fabrication and characterization of hierarchically organized nanoparticle-reinforced nanofibrous composite scaffolds

Two different techniques were used to fabricate nanoparticle-reinforced nanofibrous scaffolds with different organizations of the minerals. First, a three-dimensional (3D) cylindrical nanofibrous scaffold made of poly-l-lactide and poly(l-lactide)/collagen (1:1) was fabricated using a modified electrospinning method. An alternating dipping method and a flow version of it were used to mineralize the 3D scaffolds. Flow mineralization was found to significantly improve the distribution of the mineral nanoparticles throughout the 3D nanofibrous scaffold, while mineral nanoparticles were found only on the periphery of the static mineralized scaffold. As a result of the mineral nanoparticle distribution, the compressive strength and modulus of the flow mineralized scaffold was found to be significantly greater than that of the static mineralized scaffold, despite having a lower mineral content. Energy-dispersive X-ray analysis and X-ray diffraction studies suggest that the mineral was composed of heterogeneous phases of calcium phosphates. This study demonstrates the importance of hierarchical and deliberate organization of the nanocomponents to optimize the mechanical properties, as is often found in nature.