title: Synthesis and properties of photocross-linked poly(propylene fumarate) scaffolds.
abstract: The photocross-linking of poly(propylene fumarate) (PPF) to form porous scaffolds for bone tissue engineering applications was investigated. PPF was cross-linked using the photoinitiator bis(2,4,6-trimethylbenzoyl) phenylphosphine oxide (BAPO) and exposure to 30 min of long wavelength ultraviolet (UV) light. The porous photocross-linked PPF scaffolds (6.5 mm diameter cylinders) were synthesized by including a NaCl porogen (70, 80, and 90 wt% at cross-linking) prior to photocross-linking. After UV exposure, the samples were placed in water to remove the soluble porogen, revealing the porous PPF scaffold. As porogen leaching has not been used often with cross-linked polymers, and even more rarely with photoinitiated cross-linking, a study of the efficacy of this strategy and the properties of the resulting material was required. Results show that the inclusion of a porogen does not significantly alter the photoinitiation process and the resulting scaffolds are homogeneously cross-linked throughout their diameter. It was also shown that porosity can be generally controlled by porogen content and that scaffolds synthesized with at least 80 wt% porogen possess an interconnected pore structure. Compressive mechanical testing showed scaffold strength to decrease with increasing porogen content. The strongest scaffolds with interconnected pores had an elastic modulus of 2.3+/-0.5 MPa and compressive strength at 1% yield of 0.11+/-0.02 MPa. This work has shown that a photocross-linking/porogen leaching technique is a viable method to form porous scaffolds from photoinitiated materials.
authors.affiliation: Department of Bioengineering, Rice University, Houston, TX 77251-1892, USA.
authors.forename: J P
authors.initials: JP
authors.lastname: Fisher
authors.forename: T A
authors.initials: TA
authors.lastname: Holland
authors.forename: D
authors.initials: D
authors.lastname: Dean
authors.forename: P S
authors.initials: PS
authors.lastname: Engel
authors.forename: A G
authors.initials: AG
authors.lastname: Mikos
mesh_terms: D055592:Biophysical Phenomena; D001703:Biophysics; D001843:Bone Cements / Q000737:chemistry*; D002850:Chromatography, Gel; D003432:Cross-Linking Reagents / Q000494:pharmacology; D005650:Fumarates / Q000737:chemistry*; D008855:Microscopy, Electron, Scanning; D011126:Polypropylenes / Q000737:chemistry*; D012965:Sodium Chloride / Q000494:pharmacology; D017550:Spectroscopy, Fourier Transform Infrared; D013997:Time Factors; D014466:Ultraviolet Rays
chemical_list: D001843:Bone Cements; D003432:Cross-Linking Reagents; D005650:Fumarates; D011126:Polypropylenes; C097850:poly(propylene fumarate); D012965:Sodium Chloride