title: In vitro degradation and mechanical properties of PLA-PCL copolymer unit cell scaffolds generated by two-photon polymerization.
abstract: The manufacture of 3D scaffolds with specific controlled porous architecture, defined microstructure and an adjustable degradation profile was achieved using two-photon polymerization (TPP) with a size of 2  ×  4  ×  2 mm(3). Scaffolds made from poly(D,L-lactide-co-ɛ-caprolactone) copolymer with varying lactic acid (LA) and ɛ -caprolactone (CL) ratios (LC16:4, 18:2 and 9:1) were generated via ring-opening-polymerization and photoactivation. The reactivity was quantified using photo-DSC, yielding a double bond conversion ranging from 70% to 90%. The pore sizes for all LC scaffolds were see 300 μm and throat sizes varied from 152 to 177 μm. In vitro degradation was conducted at different temperatures; 37, 50 and 65 °C. Change in compressive properties immersed at 37 °C over time was also measured. Variations in thermal, degradation and mechanical properties of the LC scaffolds were related to the LA/CL ratio. Scaffold LC16:4 showed significantly lower glass transition temperature (T g) (4.8 °C) in comparison with the LC 18:2 and 9:1 (see 32 °C). Rates of mass loss for the LC16:4 scaffolds at all temperatures were significantly lower than that for LC18:2 and 9:1. The degradation activation energies for scaffold materials ranged from 82.7 to 94.9 kJ mol(-1). A prediction for degradation time was applied through a correlation between long-term degradation studies at 37 °C and short-term studies at elevated temperatures (50 and 65 °C) using the half-life of mass loss (Time (M1/2)) parameter. However, the initial compressive moduli for LC18:2 and 9:1 scaffolds were 7 to 14 times higher than LC16:4 (see 0.27) which was suggested to be due to its higher CL content (20%). All scaffolds showed a gradual loss in their compressive strength and modulus over time as a result of progressive mass loss over time. The manufacturing process utilized and the scaffolds produced have potential for use in tissue engineering and regenerative medicine applications.
authors.affiliation: Advanced Materials Research Group, Faculty of Engineering, University of Nottingham, UK. Physics Department, Faculty of Science, Mansoura University, 35516, Egypt.
authors.forename: R M
authors.initials: RM
authors.lastname: Felfel
authors.forename: Leander
authors.initials: L
authors.lastname: Poocza
authors.forename: Miquel
authors.initials: M
authors.lastname: Gimeno-Fabra
authors.forename: Tobias
authors.initials: T
authors.lastname: Milde
authors.forename: Gerhard
authors.initials: G
authors.lastname: Hildebrand
authors.forename: Ifty
authors.initials: I
authors.lastname: Ahmed
authors.forename: Colin
authors.initials: C
authors.lastname: Scotchford
authors.forename: Virginie
authors.initials: V
authors.lastname: Sottile
authors.forename: David M
authors.initials: DM
authors.lastname: Grant
authors.forename: Klaus
authors.initials: K
authors.lastname: Liefeith
mesh_terms: D020341:Absorbable Implants; D019245:Compressive Strength / Q000528:radiation effects; D055119:Elastic Modulus / Q000528:radiation effects; D004867:Equipment Design; D019544:Equipment Failure Analysis; D019344:Lactic Acid / Q000737:chemistry*; D008027:Light; D008422:Materials Testing; D017785:Photons; D011091:Polyesters / Q000737:chemistry*; D011108:Polymers / Q000138:chemical synthesis / Q000737:chemistry* / Q000528:radiation effects; D066330:Printing, Three-Dimensional; D013314:Stress, Mechanical; D013718:Tensile Strength / Q000528:radiation effects; D023822:Tissue Engineering / Q000295:instrumentation / Q000379:methods; D054457:Tissue Scaffolds
chemical_list: D011091:Polyesters; D011108:Polymers; C016240:polycaprolactone; D019344:Lactic Acid; C033616:poly(lactide)