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Background: /Objective: The treatment of bone defect has always been a difficult problem in orthopedic clinic. The search for alternative biodegradable implants is a hot topic. The development of biodegradable magnesium scaffolds for the treatment of bone defects has long been a goal of the public. Methods: In this study, we proposed a porous magnesium scaffold prepared by 3D gel printing and surface modification with an additional calcium phosphate coating and use of its strength, degradability and slow degradation rate in a bone graft substitute material. The porous magnesium granular scaffold was prepared by 3D gel printing technology and modified by DCPD (Dibasic Calcium Phosphate Dihydrate) coating. The biocompatibility, degradation rate, and osteogenic ability of the scaffold were evaluated in vitro and in vivo. Results: The biocompatibility, in vivo degradation and bone defect healing response of the implants were investigated. Porous magnesium scaffolds were successfully prepared, and the strength of sintered scaffolds reached 5.38 ​MPa. The degradation rates of scaffolds were significantly reduced after coating with DCPD. The cell compatibility evaluation showed that DCPD-coated Mg scaffold was suitable for cell proliferation. In vivo biosafety monitoring showed that scaffold implantation did not cause an increase in Mg ion concentration in vivo, and no toxic damage was detected in the liver or kidney. Micro-CT and pathological results showed that a large amount of new bone was formed at 6 weeks. At 12 weeks, approximately 52% of the scaffold volume remained. At 24 weeks, osteogenesis, which was stimulated by some residual scaffold, still can be observed. In summary, this study suggests that 3D gel-printed DCPD-coated porous magnesium scaffolds have great potential as bone graft alternatives. Conclusion: In summary, this study suggests that 3D gel-printed DCPD-coated porous magnesium scaffolds have great potential as bone graft alternatives. The Translational potential of this article: The translational potential of this article is to make use of the advantages of 3D gel printing technology with higher efficiency and lower cost compared with SLM and SLS technologies, and use pure magnesium powder as raw material to prepare degradable porous magnesium metal scaffolds, opening up a new technical route for the preparation of degradable porous magnesium scaffolds which are made for bone defect regeneration in the future.

Porous magnesium (Mg) scaffolds were successfully prepared by 3D gel-printing (3DGP) technology in this study. Absolute ethanol and epoxy resin were mixed to prepare the premixed solution and then Mg powders were mixed into the premixed solution to prepare the slurry which was used to print Mg scaffolds by 3DGP. After debinding and sintering, the properties and microstructure of the samples were tested. The scaffolds were implanted into the femoral condyle of rats, and the implanting position was observed at the first, the third and the fifth week. The results showed that the highest compressive strength of Mg scaffolds can reach 20.05 MPa at a porosity of 64.4% after sintered at 610 °C. In order to study the degradation and osteogenesis of the scaffolds, pure Mg, oxide-coated Mg and TCP scaffolds were implanted into the femoral condyle of rats and compared with the blank control group. The results showed that oxide-coated Mg scaffolds have relatively good biocompatibility and degradability. According to the results of CT (Computed Tomography) and X-ray, the oxide-coated Mg scaffolds can promote cancellous bone osteogenesis and can delay the degradation of pure Mg scaffolds.

The water-based magnetic fluids with nanometric Cu(sub x)Fe(sub 1-x)OFe2O3 particles were prepared by the two-step method, where the copper element, which is useful in tumor therapy, was coprecipitated with Fe(super 2+) and Fe(super 3+). The results showed that the magnetization of the magnetic particles decreased with increasing contents of diamagnetic copper element.

Cobalt nanoparticles with dissimilar sizes and shapes are synthesized by thermal decomposition of cobalt acetate in the presence of various amounts of surfactants. It was observed that combining surfactants consisting of sufficient amount of oleic acid together with polyvinylpyrrolidone and oleylamine resulted in well-dispersed cubic cobalt nanoparticles of ~25 nm in average size.

Ultrasuperpara magnetic iron oxide (USPIO) nanoparticles were synthesized with iron chloride using a sonochemical method. The size of the USPIO nanoparticles was controlled by ultrasonic exposure time and power. The USPIO nanoparticles had a narrow size distribution, a perfect magnetite crystal structure, and high saturation magnetization. The magnetic resonance imaging (MRI) contrast agent was prepared by coating the USPIO and dispersing it with biocompatible chitosan. In vivo testing in New Zealand white rabbits confirmed the effectiveness of the USPIO nanoparticles as a MRI contrast agent. [ABSTRACT FROM AUTHOR]