title: Mechanical study of polycaprolactone-hydroxyapatite porous scaffolds created by porogen-based solid freeform fabrication method.
abstract: METHODS
  Polycaprolactone (PCL) and polycaprolactone-hydroxyapatite (PCL-HA) scaffolds with 600-µm pore size were fabricated by drop-on-demand printing (DDP) structured porogen method followed with injection molding. Specimens with special dimensions of 4.2×4.2×5.4 mm3 and 6.6×6.6×13.8 mm3 were designed and fabricated for compression and tensile tests, respectively. The mechanical study was performed on both solid and porous PCL and PCL-HA samples. The effect on mechanical properties of the HA content ratio in PCL-HA composites was investigated.
  
  
  RESULTS
  Porous scaffold made of 80/20 PCL-HA composite had an ultimate compressive strength of 3.7±0.2 MPa and compression modulus of 61.4±3.4 MPa, which is in the range of reported trabecular bone's compressive strength. Increasing the concentration of HA in the composites raised compressive properties and stiffness significantly (P<0.05), which demonstrates that PCL-HA composites have the potential for application in bone regeneration. Tensile test of solid PCL and PCL-HA composites showed that the ultimate tensile strength and tensile modulus increased with increases of the concentration of HA in the composites. The tensile test was also conducted on PCL porous scaffold; the result indicated that the scaffold was slightly softer and weaker in tension compared with compression.
  
  
  CONCLUSIONS
  Combining compression and tensile test results, our study may guide the possible application of these biomaterials in bone tissue engineering and support further development of microstructure-based models of scaffold mechanical properties.
authors.affiliation: Department of Mechanical Engineering and Mechanics, Drexel University, Philadelphia, Pennsylvania - USA.
authors.forename: Lin
authors.initials: L
authors.lastname: Lu
authors.forename: Qingwei
authors.initials: Q
authors.lastname: Zhang
authors.forename: David M
authors.initials: DM
authors.lastname: Wootton
authors.forename: Richard
authors.initials: R
authors.lastname: Chiou
authors.forename: Dichen
authors.initials: D
authors.lastname: Li
authors.forename: Bingheng
authors.initials: B
authors.lastname: Lu
authors.forename: Peter I
authors.initials: PI
authors.lastname: Lelkes
authors.forename: Jack
authors.initials: J
authors.lastname: Zhou
mesh_terms: D018786:Bone Substitutes / Q000138:chemical synthesis*; D019245:Compressive Strength; D017886:Durapatite / Q000737:chemistry*; D055119:Elastic Modulus; D004867:Equipment Design; D019544:Equipment Failure Analysis; D006244:Hardness; D008422:Materials Testing; D054802:Molecular Imprinting / Q000379:methods*; D011091:Polyesters / Q000737:chemistry*; D016062:Porosity; D013718:Tensile Strength; D054457:Tissue Scaffolds
chemical_list: D018786:Bone Substitutes; D011091:Polyesters; C016240:polycaprolactone; D017886:Durapatite