title: Porous and strong bioactive glass (13-93) scaffolds prepared by unidirectional freezing of camphene-based suspensions.
abstract: Scaffolds of 13-93 bioactive glass (6Na(2)O, 12K(2)O, 5MgO, 20CaO, 4P(2)O(5), 53SiO(2); wt.%) with an oriented pore architecture were formed by unidirectional freezing of camphene-based suspensions, followed by thermal annealing of the frozen constructs to grow the camphene crystals. After sublimation of the camphene, the constructs were sintered (1 h at 700°C) to produce a dense glass phase with oriented macropores. The objective of this work was to study how constant freezing rates (1-7°C min(-1)) during the freezing step influenced the pore orientation and mechanical response of the scaffolds. When compared to scaffolds prepared by freezing the suspensions on a substrate kept at a constant temperature of 3°C (time-dependent freezing rate), higher freezing rates resulted in better pore orientation, a more homogeneous microstructure and a marked improvement in the mechanical response of the scaffolds in compression. Scaffolds fabricated using a constant freezing rate of 7°C min(-1) (porosity=50±4%; average pore diameter=100 μm), had a compressive strength of 47±5 MPa and an elastic modulus of 11±3 GPa (in the orientation direction). In comparison, scaffolds prepared by freezing on the constant-temperature substrate had strength and modulus values of 35±11 MPa and 8±3 GPa, respectively. These oriented bioactive glass scaffolds prepared by the constant freezing rate route could potentially be used for the repair of defects in load-bearing bones, such as segmental defects in the long bones.
authors.affiliation: Department of Materials Science, Missouri University of Science and Technology, Rolla, MO 65409, USA.
authors.forename: Xin
authors.initials: X
authors.lastname: Liu
authors.forename: Mohamed N
authors.initials: MN
authors.lastname: Rahaman
authors.forename: Qiang
authors.initials: Q
authors.lastname: Fu
authors.forename: Antoni P
authors.initials: AP
authors.lastname: Tomsia
mesh_terms: D000081008:Bicyclic Monoterpenes; D001672:Biocompatible Materials / Q000737:chemistry; D018786:Bone Substitutes / Q000737:chemistry; D019245:Compressive Strength; D003460:Crystallization; D004548:Elasticity; D005615:Freezing; D005898:Glass / Q000737:chemistry*; D006801:Humans; D008422:Materials Testing; D016062:Porosity; D013314:Stress, Mechanical; D013729:Terpenes / Q000737:chemistry*; D054457:Tissue Scaffolds / Q000737:chemistry*; D016474:Weight-Bearing
chemical_list: C553965:13-93 bioactive glass; D000081008:Bicyclic Monoterpenes; D001672:Biocompatible Materials; D018786:Bone Substitutes; D013729:Terpenes; C019286:camphene