Effect of porosity on mechanical properties of porous tantalum scaffolds produced by electron beam powder bed fusion

The effect of porosity on compressive,bending,and tensile properties of the porous tantalum scaffolds fabricated by electron beam powder bed fusion(EB-PBF)was investigated.The porous tantalum scaffolds with porosity from 69%to 77.8%were obtained by varying the designed porosity and adjusting the processing parameters.It is found that the pores and unfused powder decrease with the increase of deposited energy density.The decrease of porosity leads to an improvement in mechanical properties.The relevancy between compressive/bending/tensile yield strength and relative density can be described appropriately by exponential model,while the relationship between elastic modulus and relative density is in good agreement with the Gibson-Ashby model.All the porous tantalum scaffolds exhibit good ductility in compressive,bending and tensile tests.No fragmentation of struts is observed during the compression process,but cracks are formed on the strut surface after 90°bending,mainly due to the high sensibility to defects caused by the oxide.

Fabrication, bacteriostasis and osteointegration properties researches of the additively-manufactured porous tantalum scaffolds loading vancomycin

Infected bone defects(IBDs)remains a challenging problem for orthopedists.Clinically,routine management for IBDs has two stages:debridement and systematic antibiotics administration to control infection,and secondary grafting to repair bone defects.Whereas the efficacy is not satisfactory,because the overuse of antibiotics may lead to systemic toxicity,and the emergence of drug-resistant bacteria,as well as the secondary surgery would cause additional trauma and economic burden to the patients.Therefore,it is imperative to develop a novel scaffold for one-stage repair of IBDs.In this study,vancomycin(Van)was encapsulated into poly(lactic co-glycolic acid)(PLGA)microspheres through the double emulsion method,which were then loaded into the additively-manufactured porous tantalum(AM-Ta)through gelatin methacryloyl(GelMA)hydrogel to produce the composite Ta/GelMA hydrogel(Gel)/PLGA/vancomycin(Van)scaffolds for repairing IBDs.Physiochemical characterization of the newly-developed scaffold indicated that the releasing duration of Van was over 2 weeks.Biological experiments indicated good biocompatibility of the composite scaffold,as well as bacteriostasis and osteointegration properties,which showed great potential for clinical application.The construction of this novel scaffold would provide new sight into the development of orthopaedic implants,shedding a novel light on the treatment of IBDs.

Porous tantalum-composited gelatin nanoparticles hydrogel integrated with mesenchymal stem cell-derived endothelial cells to construct vascularized tissue in vivo

The ideal scaffold material of angiogenesis should have mechanical strength and provide appropriate physiological microporous structures to mimic the extracellular matrix environment.In this study,we constructed an integrated three-dimensional scaffold material using porous tantalum(pTa),gelatin nanoparticles(GNPs)hydrogel,and seeded with bone marrow mesenchymal stem cells(BMSCs)-derived endothelial cells(ECs)for vascular tissue engineering.The characteristics and biocompatibility of pTa and GNPs hydrogel were evaluated by mechanical testing,scanning electron microscopy,cell counting kit,and live-cell assay.The BMSCs-derived ECs were identified by flow cytometry and angiogenesis assay.BMSCs-derived ECs were seeded on the pTa-GNPs hydrogel scaffold and implanted subcutaneously in nude mice.Four weeks after the operation,the scaffold material was evaluated by histomorphology.The superior biocompatible ability of pTa-GNPs hydrogel scaffold was observed.Our in vivo results suggested that 28 days after implantation,the formation of the stable capillary-like network in scaffold material could be promoted significantly.The novel,integrated pTa-GNPs hydrogel scaffold is biocompatible with the host,and exhibits biomechanical and angiogenic properties.Moreover,combined with BMSCs-derived ECs,it could construct vascular engineered tissue in vivo.This study may provide a basis for applying pTa in bone regeneration and autologous BMSCs in tissue-engineered vascular grafts.