title: Oriented bioactive glass (13-93) scaffolds with controllable pore size by unidirectional freezing of camphene-based suspensions: Microstructure and mechanical response.
abstract: Scaffolds of 13-93 bioactive glass (composition 6.0 Na₂O, 7.9 K₂O, 7.7 MgO, 22.1 CaO, 1.7 P₂O₅, 54.6 SiO₂ (mol.%)) containing oriented pores of controllable diameter were prepared by unidirectional freezing of camphene-based suspensions (10 vol.% particles) on a cold substrate (-196 °C or 3 °C). By varying the annealing time (0-72 h) to coarsen the camphene phase, constructs with the same porosity (86 ± 1%) but with controllable pore diameters (15-160 μm) were obtained after sublimation of the camphene. The pore diameters had a self-similar distribution that could be fitted by a diffusion-controlled coalescence model. Sintering (1 h at 690 °C) was accompanied by a decrease in porosity and pore diameter, the magnitude of which depended on the pore size of the green constructs, giving scaffolds with a porosity of 20-60% and average pore diameter of 6-120 μm. The compressive stress vs. deformation response of the sintered scaffolds in the orientation direction was linear, followed by failure. The compressive strength and elastic modulus in the orientation direction varied from 180 MPa and 25 GPa (porosity=20%) to 16 MPa and 4 GPa (porosity=60%), respectively, which were 2-3 times larger than the values in the direction perpendicular to the orientation. The potential use of these 13-93 bioactive glass scaffolds for the repair of large defects in load-bearing bones, such as segmental defects in long bones, is discussed.
authors.affiliation: Department of Materials Science and Engineering, Center for Bone and Tissue Repair and Regeneration, Missouri University of Science and Technology, Rolla, 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
mesh_terms: D000081008:Bicyclic Monoterpenes; D019245:Compressive Strength; D005615:Freezing; D005898:Glass / Q000737:chemistry*; D006801:Humans; D055595:Mechanical Phenomena; D008855:Microscopy, Electron, Scanning; D016062:Porosity; D013535:Suspensions; D013729:Terpenes / Q000737:chemistry*; D054457:Tissue Scaffolds / Q000737:chemistry*; D014783:Viscosity
chemical_list: C553965:13-93 bioactive glass; D000081008:Bicyclic Monoterpenes; D013535:Suspensions; D013729:Terpenes; C019286:camphene
references.citation: J Biomed Mater Res A. 2010 Oct;95(1):235-44
references.pmid: 20574983
references.citation: J Mater Sci Mater Med. 2006 Jul;17(7):583-96
references.pmid: 16770542
references.citation: J Biomed Mater Res. 1998 Sep 15;41(4):527-33
references.pmid: 9697024
references.citation: Acta Biomater. 2009 May;5(4):1319-27
references.pmid: 19112055
references.citation: Biomaterials. 2006 Nov;27(32):5480-9
references.pmid: 16857254
references.citation: J Biomed Mater Res. 1997 May;35(2):249-54
references.pmid: 9135173
references.citation: J Clin Invest. 1953 Apr;32(4):292-8
references.pmid: 13052686
references.citation: J Biomed Mater Res. 1970 Sep;4(3):433-56
references.pmid: 5469185
references.citation: J Biomed Mater Res A. 2010 Oct;95(1):164-71
references.pmid: 20544804
references.citation: J Biomed Mater Res A. 2010 Jun 15;93(4):1380-90
references.pmid: 19911380
references.citation: Clin Orthop Relat Res. 1999 Oct;(367 Suppl):S419-23
references.pmid: 10546664
references.citation: Acta Biomater. 2008 Nov;4(6):1854-64
references.pmid: 18519173
references.citation: Med Eng Phys. 1995 Jul;17(5):347-55
references.pmid: 7670694
references.citation: J Biomed Mater Res B Appl Biomater. 2008 Jul;86(1):125-35
references.pmid: 18098195
references.citation: Minim Invasive Ther Allied Technol. 2002 May;11(3):107-16
references.pmid: 16754059
references.citation: J Biomed Mater Res B Appl Biomater. 2008 Aug;86(2):514-22
references.pmid: 18338786