Abstract
The reproduction of a 3D bone structure with suitable porosity, which allows the flow of nutrients, blood, oxygen and mineral, remains a problem using conventional methods. A material that mimics their properties was developed by optimizing the ratio of a biodegradable blend of immiscible polylactic acid (PLA) and poly-e-caprolactone (PCL). In this study, PLA and PCL particularly optimize the strength of the artificial cancellous bone by supplying the initial support strength lasting 6 months to 2 years and allowing for the gradual degradation desired in the human body. This study focused on the mechanical properties of successfully printed 3D structures. The ultimate tensile strength was modified by blending different ratios of PLA and PCL resulting in an optimum value of approximately 30 MPa when the ratio of PLA to PCL reached 3:1. The addition of 1 wt.% of titanium dioxide (TiO2) to the immiscible PLA/PCL composite and the modification of the interface area between them resulted in the formation of a binding force that allowed for an increase in the tensile strength up to 37 MPa. Besides the mechanical properties, the in vitro biocompatibility of PLA/ PCL/TiO2 composites was examined. A vigorous cell growth was observed in the cells cultivated with the PLA/PCL/TiO2 composites and the unimpeded ability to differentiate into osteoblast also was found. The resulting properties of the 3D printed structures indicate promising applications in the fields of bone tissue engineering and cancellous bone grafting.
Highlights
The reproduction of a 3D bone structure with suitable porosity, which allows the flow of nutrients, blood, oxygen and mineral, remains a problem using conventional methods
Some kinds of metal ions released over a period of time are toxic in the human body, and even if some of them are normal components of the body, they can become toxic at high dosage [7]
The graph shows the strength of the polymers improving with increasing percentage of polylactic acid (PLA)
Summary
The reproduction of a 3D bone structure with suitable porosity, which allows the flow of nutrients, blood, oxygen and mineral, remains a problem using conventional methods. The choice of bone graft depends on varying considerations including the intended clinical application, defect size, mechanical properties, availability, required bioactivity (osteoconductive/osteoinductive/ osteogenic), handling problem, cost and ethical issues [2]. Once these issues have been considered, the types of grafts can be classified as autograft, allograft and bone graft substitutes, each with its own advantages and disadvantages. The concept of bone tissue engineering includes the design and building of a synthetic frame that will mimic the mechanical properties of the bone. PLA and PCL are synthetic biodegradable thermoplastic polymers, and are prominently used as a main material because they can be used in the human body for surgery [13,14]. The complex nature of the bones with its different porosity areas (cortical and cancellous) can be recreated by 3D printing
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