Processing of polycaprolactone and hydroxyapatite to fabricate graded electrospun composites for tendon-bone interface regeneration

The process of electrospinning is utilized with different approaches including conventional electrospinning, extrusion electrospinning, and electroblowing to form nanofibrous meshes and composites. Here, we report on the quality and properties of spatially graded polycaprolactone (PCL) and nano-hydroxyapatite (nHA) composite meshes fabricated with multiple-spinneret electrospinning. The composite meshes were characterized in terms of the amount of spatially allocated nHA concentration across the mesh, fiber diameter, porosity, pore size, and hydrophilicity of meshes. Results show that linearly and continuously varying nHA concentration distribution, i.e. graded structure, can be accomplished across the mesh thickness using multiple-spinneret electrospinning, which is in accordance with the change of mineral concentration observed in native tendon-bone interface. Furthermore, incorporation of nanoparticles into nanofibers led to increased fiber diameter as depicted by a shift in fiber diameter distribution, a significant increase in mean fiber diameter from 361 +/- 9 nm to 459 +/- 21 nm, and an increase in contact angle from 120.01 +/- 2.77 degrees to 115.24 +/- 1.17 degrees. These findings suggest that the composite meshes formed in this study could serve as model systems to be used as scaffolds in tendon-bone tissue engineering application in particular, and for other tissue-tissue interfaces in a broader context.