Combination of PLA Micro-fibers and PCL-Gelatin Nano-fibers for Development of Bone Tissue Engineering Scaffolds
In tissue engineering, biodegradable porous scaffolds have been employed to replace damaged tissues. These scaffolds are fabricated by conventional techniques such as fiber-bonding, solvent casting, particulate leaching and advanced ones like selective laser sintering, 3-dimentional printing and fused deposition modeling. The main issues limiting conventional techniques are inability to fabricate scaffolds with a highly interconnected porous structure and favorably regular construction with reproducible morphology. Hence researchers go towards advanced techniques with more flexibility. In this study, FDM and electrospinning (ES) techniques have been applied in order to develop multi-layered scaffolds consisting of micro- and nano- fibers for bone tissue engineering applications. While micro fibrous layers were fabricated via FDM process, nano-fibrous layers were developed using ES technique. Although FDM technique has unique features, its fiber size limits to micro sizes. One of the trends that are useful for eliminating this issue is getting benefit of adding nano-fibers to scaffold's construction. These nano-fibers not only reduce total pore size of the scaffold, but also could improve cell functions. While poly (lactic-acid) (PLA) was used for FDM process, a mixture of poly (caprolactone) (PCL) and gelatin were applied for electrospinning process to develop interconnected pores with appropriate mechanical properties and degradation rate. The multi-layered scaffolds were examined using electron microscopy (SEM) and their mechanical properties were evaluated. The porosity of the scaffolds was about 40% and results also demonstrated that nano-fibers with size of 200 nm in diameter had good adhesion to micro-fibers and may provide better cell attachment and proliferation.