Fabrication of poly(lactic acid)-cellulose acetate core-shell electrospun fibers with improved tensile strength and biocompatibility for bone tissue engineering

The employment of individual poly(lactic acid) (PLA) or cellulose acetate (CA) electrospun fibers as bone tissue replacement was restricted by the weak mechanical properties of CA and the poor cell-affinity of PLA. In this study, core-shell fibers with PLA as the core component and CA as the shell layer were fabricated via coaxial electrospinning with significant improvements in the tensile strength and biocompatibility in comparison to individual PLA and CA fibers and blend PLA/CA fibers. The employment of a core-to-shell flow rate ratio of 0.25:0.5 mL/hr:mL/hr resulted in the formation of defect-free and uniformly distributed PLA-CA core-shell fibers (cs-PLA1-CA2) with the highest ultimate tensile strength (19.53 +/- 1.68 MPa) and Young's modulus (0.62 +/- 0.09 GPa) among all core-shell fibers produced in this study. These tensile values match the tensile properties of native cancellous bone and represent around a 130% and 160% improvement in strength and stiffness compared to monolithic CA fibers, respectively. Higher weight fraction and improved crystallinity of PLA-core were revealed to contribute to this mechanical enhancement of cs-PLA1-CA2. An in vitro biocompatibility study was conducted using human fetal osteoblasts (hFOB). The results indicate improved cell distribution, better cell-scaffold attachment, and higher cell proliferation and alkaline phosphatase (ALP) activity of cs-PLA1-CA2 compared to monolithic PLA and blend PLA/CA fibers, while matching the growth performance of hFOB seeded on tissue culture polystyrene (TCP). The PLA-CA core-shell fibers produced in this study hold great promise for use as bone tissue scaffolds.