title: Impregnation of β-tricalcium phosphate robocast scaffolds by in situ polymerization.
abstract: Ring-opening polymerization of ε-caprolactone (ε-CL) and L-lactide (LLA) was performed to impregnate β-tricalcium phosphate (β-TCP) scaffolds fabricated by robocasting. Concentrated colloidal inks prepared from β-TCP commercial powders were used to fabricate porous structures consisting of a 3D mesh of interpenetrating rods. ε-CL and LLA were in situ polymerized within the ceramic structure by using a lipase and stannous octanoate, respectively, as catalysts. The results show that both the macropores inside the ceramic mesh and the micropores within the ceramic rods are full of polymer in either case. The mechanical properties of scaffolds impregnated by in situ polymerization (ISP) are significantly increased over those of the bare structures, exhibiting similar values than those obtained by other, more aggressive, impregnation methods such as melt-immersion (MI). ISP using enzymatic catalysts requires a reduced processing temperature which could facilitate the incorporation of growth factors and other drugs into the polymer composition, thus enhancing the bioactivity of the composite scaffold. The implications of these results for the optimization of the mechanical and biological performance of scaffolds for bone tissue engineering applications are discussed.
authors.affiliation: Departamento de Ingeniería Mecánica, Energética y de los Materiales, Universidad de Extremadura, Avda de Elvas s/n, 06006, Badajoz, Spain.
authors.forename: Francisco J
authors.initials: FJ
authors.lastname: Martínez-Vázquez
authors.forename: Fidel H
authors.initials: FH
authors.lastname: Perera
authors.forename: Inge
authors.initials: I
authors.lastname: van der Meulen
authors.forename: Andreas
authors.initials: A
authors.lastname: Heise
authors.forename: Antonia
authors.initials: A
authors.lastname: Pajares
authors.forename: Pedro
authors.initials: P
authors.lastname: Miranda
mesh_terms: D002130:Calcium Phosphates / Q000737:chemistry*; D019245:Compressive Strength; D008422:Materials Testing; D008855:Microscopy, Electron, Scanning; D011091:Polyesters / Q000737:chemistry; D058105:Polymerization; D013314:Stress, Mechanical; D023822:Tissue Engineering / Q000379:methods*; D054457:Tissue Scaffolds / Q000737:chemistry*
chemical_list: D002130:Calcium Phosphates; D011091:Polyesters; C485817:beta-tricalcium phosphate; C016240:polycaprolactone
keywords: mechanical properties; polymer impregnation; ring opening polymerization; robocasting; scaffolds