Effects of Gradient and Offset Architectures on the Mechanical and Biological Properties of 3-D Melt Electrowritten (MEW) Scaffolds

This study describes the fabrication and characterization of three-dimensional (3-D) poly(ϵ-caprolactone) (PCL) scaffolds with defined pore architectures prepared using the melt electrowriting (MEW) technique. Three homogeneous pore-sized (250, 500, and 750 μm) scaffolds, two fiber offset (30/70% and 50/50%), and a three-layered (250 μm bottom-500 μm middle-750 μm top) gradient pore-sized scaffolds were designed and printed with ∼10 μm fibers. The mechanical properties (tensile and compression tests), total surface area, porosity of these scaffolds, and their ability to promote the attachment and proliferation of human osteoblasts were then compared. All scaffolds induced good tensile properties; however, they reacted differently during compressive testing. The offset 30/70 scaffold had the highest surface area to volume ratio which enhanced osteoblast attachment after 3 days of cell culture. While the highest initial level of osteoblast attachment at day 1 was found on the 250 μm homogeneous scaffold, the highest degree of cell proliferation and infiltration at day 30 was observed in the three-layered graded porosity scaffold. In terms of physical and biological properties to support bone cell distribution and migration through the entire structure of the scaffold, our results suggest that melt electrowritten offset and gradient scaffolds are good candidate platforms for cell infiltration and growth compared to homogeneous scaffolds.