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

Document Type : Original Article


Department of Life Science Engineering, Faculty of New Science and Technology, University of Tehran, Tehran, Iran



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.

Graphical Abstract

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


[1]    O'Brien FJ. Biomaterials & scaffolds for tissue engineering. Materials Today. 2011;14(3):88-95.
[2]    Evans ND, Gentleman E, Polak JM. Scaffolds for stem cells. Materials Today. 2006;9(12):26-33.
[3]    S.Hong, G.H.Kim. Fabrication of size-controlled three-dimensional structures consisting of electrohydrodynamically produced polycaprolactone micro/nanofibers. Applied Physics A. 2011:1009-14.
[4]    P.Yilgor, R.A.Sousa, R.L.Reis, N.Hasirci, Vasif.Hasirci. 3D Plotted PCL Scaffolds for Stem Cell Based Bone Tissue Engineering. Macromolecular Symposia. 2008;269(1):92-9.
[5]    A.DiLuca, K.Szlazak, I.Lorenzo-Moldero, C.Ghebes, A.Lepedda, W.Swieszkowski, et al. Influencing chondrogenic differentiation of human mesenchymal stromal cells in scaffolds displaying a structural gradient in pore size. Acta Biomaterailia. 2016.
[6]    Di Luca A, Van Blitterswijk C, Moroni L. The osteochondral interface as a gradient tissue: From development to the fabrication of gradient scaffolds for regenerative medicine. Birth Defects Research Part C: Embryo Today: Reviews. 2015;105(1):34-52.
[7]    J.M.Sobral, S.G.Caridade, R.A.Sousa, J.F.Mano, R.L.Reis. Three-dimensional plotted scaffolds with controlled pore size gradients: Effect of scaffold geometry on mechanical performance and cell seeding efficienc. Acta Biomaterailia. 2011;7:1009–18.
[8]    S.HeangOh, I.KyuPark, J.M.Kim, J.H.Lee. In vitro and in vivo characteristics of PCL scaffolds with pore size gradient fabricated by a centrifugation method. Biomaterials. 2007;28:1664–71.
[9]    Salmoria, G.Vitor, al. e. Rapid manufacturing of polyethylene parts with controlled pore size gradients using selective laser sintering. Materials Research. 2007;10:211-4.
[10] Grey CP, Newton ST, Bowlin GL, Haas TW, Simpson DG. Gradient fiber electrospinning of layered scaffolds using controlled transitions in fiber diameter. Biomaterials. 2013;34(21):4993-5006.
[11] B.A.Harleya, A.Z.Hastingsb, I.V.Yannasa, A.Sanninoa. Fabricating tubular scaffolds with a radial pore size gradient by a spinning technique. Biomaterials. 2006;27:866-74.
[12] H.Wu, Y.Wan, X.Cao, S.Dalai, S.Wang, S.Zhang. Fabrication of chitosan-g-polycaprolactone copolymer scaffolds with gradient porous microstructures. Materials Letters. 2008;62:2733-6.
[13] Q.Zhang, H.Lu, N.Kawazoe, G.Chen. Preparation of collagen porous scaffolds with a gradient pore size structure using ice particulates. Materials Letters. 2013;107:280-3.
[14] Bracaglia LG, Smith BT, Watson E, Arumugasaamy N, Mikos AG, Fisher JP. 3D printing for the design and fabrication of polymer-based gradient scaffolds. Acta Biomaterialia. 2017;56:3-13.
[15] Surmeneva MA, Surmenev RA, Chudinova EA, Koptioug A, Tkachev MS, Gorodzha SN, et al. Fabrication of multiple-layered gradient cellular metal scaffold via electron beam melting for segmental bone reconstruction. Materials & Design. 2017;133:195-204.
[16] F.Mirahmadi, M.Tafazzoli-Shadpour, M.A.Shokrgozar, S.Bonakdar. Enhanced mechanical properties of thermosensitive chitosan hydrogel by silk fibers for cartilage tissue engineering. Materials Science and Engineering. 2013;33:4786-94.
[17] M.E.Gomes. A bone tissue engineering strategy based on starch scaffolds and bone marrow cells cultured in a flow perfusion bioreactor. 2004.
[18] L.Ting, Klein R. Viscous Vortical Flows: Springer-Verlag Berlin Heidelberg; 1991. 222 p.
[19] X.MA.PETER, CHOI J-W. Biodegradable Polymer Scaffolds with Well-Defined Interconnected Spherical Pore Network. Tissue Engineering. 2001;7:23-33.
[20] CM.Murphy, MG.Haugh, FJ.O'Brien. The effect of mean pore size on cell attachment, proliferation and migration in collagen-glycosaminoglycan scaffolds for bone tissue engineering. Biomaterials. 2010;31:461-6.
[21] AM.Martins, MI.Santos, HS.Azevedo, PB.Malafaya, RL.Reis. Natural origin scaffolds with in situ pore forming capability for bone tissue engineering applications. Acta Biomaterailia. 2008;4.
[22] PX.Ma, R.Zhang. Synthetic nano-scale fibrous extracellular matrix. Journal of Biomedical Materials Research. 1999;46:60-72.
[23] PX.Ma, R.Zhang, G.Xiao, R.Franceschi. Engineering new bone tissue in vitro on highly porous poly(alpha-hydroxyl acids)/hydroxyapatite composite scaffolds. journal of Biomedical Materials Research. 2001;54:284-93.
[24] R.Zhang, PX.Ma. Synthetic nano-fibrillar extracellular matrices with predesigned macroporous architectures. Journal of Biomedical Materials Research. 2000;52:430-8.
[25] Koupaei N, Karkhaneh A, Daliri Joupari M. Preparation and characterization of (PCL‐crosslinked‐PEG)/hydroxyapatite as bone tissue engineering scaffolds. Journal of Biomedical Materials Research Part A. 2015;103(12):3919-26.
[26] Eshraghi S, Das S. Mechanical and microstructural properties of polycaprolactone scaffolds with one-dimensional, two-dimensional, and three-dimensional orthogonally oriented porous architectures produced by selective laser sintering. Acta Biomaterialia. 2010;6(7):2467-76.
[27]  Jafarkhan Mi, Salehi Z, Aidun A, Shokrgozar MA. Bioprinting in Vascularization Strategies. Iranian Biomedical Journal (IBJ);2019:23(1):9-20.