Fabrication of three dimensional open porous regular structure of PA-2200 for enhanced strength of scaffold using selective laser sintering

Purpose Scaffolds are essentially required to have open porous structure for facilitating bone to grow. They are generally placed on those bone defective/fractured sites which are more prone to compressive loading. Open porous structure lacks in strength in comparison to solid. Selective laser sintering (SLS) process is prominently used for fabrication of polymer/composite scaffolds. So, this paper aims to study for fabrication of three-dimensional open porous scaffolds with enhanced strength, process parameters of SLS of a biocompatible material are required to be optimized. Design/methodology/approach Regular open porous structures with suitable pore size as per computer-aided design models were fabricated using SLS. Polyamide (PA-2200) was used to fabricate the specimen/scaffold. To optimize the strength of the designed structure, response surface methodology was used to design the experiments. Specimens as per ASTM D695 were fabricated using SLS and compressive testing was carried out. Analysis of variance was done for estimating contribution of individual process parameters. Optimized process parameters were obtained using a trust region algorithm and correlated with experimental results. Accuracy of the fabricated specimen/scaffold was also assessed in terms of IT grades. In vitro cell culture on the fabricated structures confirmed the biocompatibility of polyamide (PA-2200). Findings Optimized process parameters for open cell process structures were obtained and confirmed experimentally. Laser power, hatch spacing and layer thickness have contributed more in the porous part’s strength than scan speed. The accuracy of the order of IT16 has been found for all functional dimensions. Cell growth and proliferation confirmed biocompatibility of polyamide (PA-2200) for scaffold applications. Originality/value This paper demonstrates the biocompatibility of PA-2200 for scaffold applications. The optimized process parameters of SLS process for open cell structure having pore size 1.2 × 1.2 mm2 with strut diameter of 1 mm have been obtained. The accuracy of the order of IT16 was obtained at the optimized process factors.

[1]  Sanjay Kumar,et al.  An experimental design approach to selective laser sintering of low carbon steel , 2003 .

[2]  D. Kaplan,et al.  Porosity of 3D biomaterial scaffolds and osteogenesis. , 2005, Biomaterials.

[3]  Neil Hopkinson,et al.  Experimental measurement and finite element modelling of the compressive properties of laser sintered Nylon-12 , 2006 .

[4]  Shivakumar Raman,et al.  Mechanical evaluation of porous titanium (Ti6Al4V) structures with electron beam melting (EBM). , 2010, Journal of the mechanical behavior of biomedical materials.

[5]  Rupinder Singh,et al.  Process capability study of polyjet printing for plastic components , 2011 .

[6]  P. Eggli,et al.  Porous hydroxyapatite and tricalcium phosphate cylinders with two different pore size ranges implanted in the cancellous bone of rabbits. A comparative histomorphometric and histologic study of bony ingrowth and implant substitution. , 1988, Clinical orthopaedics and related research.

[7]  Neil Hopkinson,et al.  Effects of processing on microstructure and properties of SLS Nylon 12 , 2006 .

[8]  Vamsi Krishna Balla,et al.  Porous tantalum structures for bone implants: fabrication, mechanical and in vitro biological properties. , 2010, Acta biomaterialia.

[9]  P. Kasten,et al.  Porosity and pore size of beta-tricalcium phosphate scaffold can influence protein production and osteogenic differentiation of human mesenchymal stem cells: an in vitro and in vivo study. , 2008, Acta biomaterialia.

[10]  J. Weng,et al.  Fabrication of porous titanium implants with biomechanical compatibility , 2009 .

[11]  H. Fischer,et al.  Scaffolds for bone healing: concepts, materials and evidence. , 2011, Injury.

[12]  C. Pappalettere,et al.  International Journal of Biological Sciences , 2011 .

[13]  G. Lewandowicz,et al.  Polymer Biodegradation and Biodegradable Polymers - a Review , 2010 .

[14]  Pulak M. Pandey,et al.  Experimental investigations for improving part strength in selective laser sintering , 2008 .

[15]  Jorge Vicente Lopes da Silva,et al.  Dimensional error in selective laser sintering and 3D-printing of models for craniomaxillary anatomy reconstruction. , 2008, Journal of cranio-maxillo-facial surgery : official publication of the European Association for Cranio-Maxillo-Facial Surgery.

[16]  D. Hutmacher,et al.  Scaffolds in tissue engineering bone and cartilage. , 2000, Biomaterials.

[17]  Jerry Y. H. Fuh,et al.  An intelligent parameter selection system for the direct metal laser sintering process , 2004 .

[18]  Richard H. Crawford,et al.  Computational quality measures for evaluation of part orientation in freeform fabrication , 1997 .

[19]  J M García-Aznar,et al.  On scaffold designing for bone regeneration: A computational multiscale approach. , 2009, Acta biomaterialia.

[20]  Samuel K Sia,et al.  Direct patterning of composite biocompatible microstructures using microfluidics. , 2007, Lab on a chip.

[21]  Shelly R. Peyton,et al.  Intrinsic mechanical properties of the extracellular matrix affect the behavior of pre-osteoblastic MC3T3-E1 cells. , 2006, American journal of physiology. Cell physiology.

[22]  B Vamsi Krishna,et al.  Low stiffness porous Ti structures for load-bearing implants. , 2007, Acta biomaterialia.

[23]  Pulak M. Pandey,et al.  Fitment Study of Porous Polyamide Scaffolds Fabricated from Selective Laser Sintering , 2013 .

[24]  P H Krebsbach,et al.  Engineering craniofacial scaffolds. , 2005, Orthodontics & craniofacial research.

[25]  Carl Deckard,et al.  Advances in modeling the effects of selected parameters on the SLS process , 1998 .

[26]  Josep A Planell,et al.  Simulation of tissue differentiation in a scaffold as a function of porosity, Young's modulus and dissolution rate: application of mechanobiological models in tissue engineering. , 2007, Biomaterials.

[27]  I. Gibson,et al.  Material properties and fabrication parameters in selective laser sintering process , 1997 .

[28]  Stefan Lohfeld,et al.  Selective laser sintering of hydroxyapatite/poly-epsilon-caprolactone scaffolds. , 2010, Acta biomaterialia.

[29]  E. D. Rekow,et al.  Performance of degradable composite bone repair products made via three-dimensional fabrication techniques. , 2003, Journal of biomedical materials research. Part A.

[30]  Scott J Hollister,et al.  Combined use of designed scaffolds and adenoviral gene therapy for skeletal tissue engineering. , 2006, Biomaterials.

[31]  Liang Hao,et al.  The effects and interactions of fabrication parameters on the properties of selective laser sintered hydroxyapatite polyamide composite biomaterials , 2012 .

[32]  Pulak M. Pandey,et al.  Improving accuracy through shrinkage modelling by using Taguchi method in selective laser sintering , 2007 .

[33]  P. McHugh,et al.  Dependence of mechanical properties of polyamide components on build parameters in the SLS process , 2007 .

[34]  Pulak M. Pandey,et al.  Effect of delay time on part strength in selective laser sintering , 2009 .

[35]  T. Childs,et al.  Density prediction of crystalline polymer sintered parts at various powder bed temperatures , 2001 .