A Viscoelastic Study of Poly(ε-Caprolactone) Microsphere Sintered Bone Tissue Engineering Scaffold

Tissue engineering scaffolds are intended as a replacement for conventional bone grafts used in the treatment of bone damages. One of the challenges in bone tissue engineering is to fabricate scaffolds with large pores, high porosity, and at the mean time proper mechanical properties suitable for bone applications. The elastic properties Young’s modulus and yield strength) of these scaffolds have been mostly considered but since bone is a viscoelastic material it is necessary to evaluate this behavior of the scaffolds as well. In the current study the novel method of microsphere sintering as a bottom-up approach was used to fabricate porous three dimensional (3D) bone scaffolds made of poly(ε-caprolactone) with controlled properties. Different variables effective on the mechanical and architectural properties of the scaffold (including time and temperature of the sintering process) were investigated and the optimum conditions (100 min and 64.5 °C) to fabricate scaffolds with the highest possible mechanical properties and porosity were determined (Young’s modulus = 33.61 MPa, yield strength = 2.2 MPa, with 44.5% porosity). Then the viscoelastic properties of this scaffold was evaluated and studied using stress relaxation test (25% stress relaxation) and generalized Maxwell model and compared to bone. Based on these results, the highly interconnected scaffold showed proper mechanical properties, pore size and structure proper for bone tissue engineering.