Effects of amylose content on the mechanical properties of starch-hydroxyapatite 3D printed bone scaffolds

Recent efforts in the bone and tissue engineering field have been made to create resorbable bone scaffolds that mimic the structure and function of natural bone. While enhancing mechanical strength through increased ceramics loading has been shown for sintered parts, few studies have reported that the crosslinked polymer provides strength for the composite parts without post processing. The objective of this study is to assess the effect of amylose content on the mechanical and physical properties of starch-hydroxyapatite (HA) composite scaffolds for bone and tissue engineering applications. Starch-HA composite scaffolds utilizing corn, potato, and cassava sources of gelatinized starch were fabricated through the utilization of a self-designed and built solid freeform fabricator (SFF). It was hypothesized that the mechanical strength of the starch-HA scaffolds would increase with increasing amylose content based on the botanical source and weight percentage added. Overall, compressive strengths of scaffolds were achieved up to 12.49 ± 0.22 MPa, through the implementation of 5.46 wt% corn starch with a total amylose content of 1.37%. The authors propose a reinforcement mechanism through a matrix of gelled starch particles and interlocking of hydroxyl-rich amylose with hydroxyapatite through hydrogen bonding. XRD, FTIR, and FESEM were utilized to further characterize these scaffold structures, ultimately elucidating amylose as a biologically relevant reinforcement phase of resorbable bone scaffolds.