Microstructure of scaffolds exhibited by SEM. The HA were embedded in PCL, or exposed on the surface. Apparently the roughness of pore-wall surfaces increased with increasing the HA ratio. Panel (A) (800×) was an example of HA-free PCL scaffolds. Panel (B) (1000×) showed composite with low HA ratio, HA: PCL (w/w) = 1:4; while Panel (C) (500×) revealed a sample with high HA concentration, HA: PCL (w/w) = 1:1. The protruded components were confirmed as the HA by EDX (Panel D). The peaks of calcium and phosphorus were prominent and quantified the atomic ratio (Ca: P = 1.58).