title: Microstructure-dependent mechanical properties of electrospun core-shell scaffolds at multi-scale levels.
abstract: Mechanical factors among many physiochemical properties of scaffolds for stem cell-based tissue engineering significantly affect tissue morphogenesis by controlling stem cell behaviors including proliferation and phenotype-specific differentiation. Core-shell electrospinning provides a unique opportunity to control mechanical properties of scaffolds independent of surface chemistry, rendering a greater freedom to tailor design for specific applications. In this study, we synthesized electrospun core-shell scaffolds having different core composition and/or core-to-shell dimensional ratios. Two independent biocompatible polymer systems, polyetherketoneketone (PEKK) and gelatin as the core materials while maintaining the shell polymer with polycaprolactone (PCL), were utilized. The mechanics of such scaffolds was analyzed at the microscale and macroscales to determine the potential implications it may hold for cell-material and tissue-material interactions. The mechanical properties of individual core-shell fibers were controlled by core-shell composition and structure. The individual fiber modulus correlated with the increase in percent core size ranging from 0.55±0.10GPa to 1.74±0.22GPa and 0.48±0.12GPa to 1.53±0.12GPa for the PEKK-PCL and gelatin-PCL fibers, respectively. More importantly, it was demonstrated that mechanical properties of the scaffolds at the macroscale were dominantly determined by porosity under compression. The increase of scaffold porosity from 70.2%±1.0% to 93.2%±0.5% by increasing the core size in the PEKK-PCL scaffold resulted in the decrease of the compressive elastic modulus from 227.67±20.39kPa to 14.55±1.43kPa while a greater changes in the porosity of gelatin-PCL scaffold from 54.5%±4.2% to 89.6%±0.4% resulted in the compressive elastic modulus change from 484.01±30.18kPa to 17.57±1.40kPa. On the other hand, the biphasic behaviors under tensile mechanical loading result in a range from a minimum of 5.42±1.05MPa to a maximum of 12.00±1.96MPa for the PEKK-PCL scaffolds, and 10.19±4.49MPa to 22.60±2.44MPa for the gelatin-PCL scaffolds. These results suggest a feasible approach for precisely controlling the local and global mechanical characteristics, in addition to independent control over surface chemistry, to achieve a desired tissue morphogenesis using the core-shell electrospinning.
authors.affiliation: Department of Bioengineering, University of California, 900 University Ave., Riverside, CA 92521, United States.
authors.forename: Christopher B
authors.initials: CB
authors.lastname: Horner
authors.affiliation: Department of Bioengineering, University of California, 900 University Ave., Riverside, CA 92521, United States.
authors.forename: Gerardo
authors.initials: G
authors.lastname: Ico
authors.affiliation: Nanofiber Solutions, Inc., Columbus, OH 43212, United States.
authors.forename: Jed
authors.initials: J
authors.lastname: Johnson
authors.affiliation: Department of Biomedical Engineering, The Ohio State University, Columbus, OH 43210, United States.
authors.forename: Yi
authors.initials: Y
authors.lastname: Zhao
authors.affiliation: Department of Bioengineering, University of California, 900 University Ave., Riverside, CA 92521, United States. Electronic address: jnam@engr.ucr.edu.
authors.forename: Jin
authors.initials: J
authors.lastname: Nam
mesh_terms: D055119:Elastic Modulus; D005780:Gelatin / Q000737:chemistry; D007659:Ketones / Q000737:chemistry; D008422:Materials Testing; D055595:Mechanical Phenomena; D011091:Polyesters / Q000737:chemistry; D016062:Porosity; D023822:Tissue Engineering; D054457:Tissue Scaffolds
chemical_list: D007659:Ketones; D011091:Polyesters; C016240:polycaprolactone; D005780:Gelatin
keywords: Core–shell electrospinning; Electrospun fiber mechanics; Electrospun scaffold mechanics