Fabrication of polycaprolactone scaffold with gradient porous microstructure for bone tissue engineering

Abstract

Introduction: Selective laser sintering, electrospinning, Layer by Layer Assembly, porogen leaching and additive manufacturing are applied methods in fabrication of gradient scaffolds with limitations such as being expensive or complicated. Objective: The main purpose of this study was to apply a novel and simple method in fabrication of gradient scaffolds with minimum cost. Methods: Two types of homogenous and two types of gradient scaffolds were fabricated by combining layer-by-layer assembly and porogen leaching techniques in a new manner. Pore size gradient was created along the radial direction by using paraffin micro particles as porogen and two different size of syringe as mold. The first layer was made in the smaller mold, with a specific size range of porogen and the second layer was fabricated around the inner one using porogens with a different size range from the first layer. Results: Scanning electron microscope images of scaffolds showed spherical pores and the structure of gradient scaffolds showed the radial gradient with a good adhesion between layers without any detectable interface. The porosity of scaffolds was 77.5 ± 3 % and 61.3 ± 4 % for homogenous and 74 ± 2.8 % and 79.8 ± 2.3 % for gradient scaffolds which are suitable for bone tissue engineering. Mechanical properties of scaffolds were better for lower porosities. The results indicated that gradient porous structure had no considerable effect on mechanical properties. MTT assay and cell morphology tests showed scaffolds biocompatibility. Conclusion: The applied method is suitable for pore size gradient creation. Gradient scaffolds can be used to investigate the influence of pore size gradient on biologic properties, cells differentiation and cell distribution and bone formation.