In vitro study of human endothelial progenitor cells behaviour on nitrided Ni-free Ti–27Nb alloy

A superelastic Ni-free Ti–27Nb alloy has been synthesized and gas nitrided at high temperature to investigate its suitability for vascular implant applications. The cellular responses of human endothelial progenitor cells (EPCs) to both bare and nitrided Ti–27Nb alloy have been analyzed using Live/Dead staining, MTT assay, fluorescence microscopy and ELISA technique, as well as NiTi alloy for comparison. Live/Dead staining and MTT assay were performed to assess the cellular viability and proliferation, while fluorescence microscopy was used to analyze cell adhesion, cell morphology, and the expression of endothelial cell markers (VE-cadherin and von Willebrand factor). Secretion of the pro-inflammatory chemokine MCP (monocyte chemoattractant protein)-1 by the cells grown in contact with the analyzed materials was further verified using the enzyme-linked immunosorbent assay. The results obtained revealed that adhesion, spreading, viability, proliferation rate and phenotypic markers expression of EPCs were similar on the surfaces of Ti–27Nb and NiTi alloys. Cells exposed to nitrided Ti–27Nb surface exhibited significantly decreased inflammatory response, which may be beneficial for reducing in-stent restenosis incidence.     

Heating effect and biocompati bility of bacteri al magnetoso mes as potential materials used in magnetic fluid hyperthermia

Magnetic fluid hyperthermia (MFH) promises to be a viable alternative in the treatment of localized cancerous tumors.The treatment consists of introducing nanoparticles as energy absorbent agents in tu...     

In vitro and in vivo studies on biodegradable magnesium alloy

The microstructure, mechanical property, electrochemical behavior and biocompatibility of magnesium alloy(Bio De MSM^TM) were studied in the present work. The experimental results demonstrated that grain refining induced by extrusion improves the alloy strength significantly from162 MPa for the as-cast alloy to 241 MPa for the as-extruded one. The anticorrosion properties of the as-extruded alloy also increased.Furthermore, the hemolysis ratio was decreased from 4.7% for the as-cast alloy to 2.9% for the as-extruded one, both below 5%. Bio De MSM^TMalloy shows good biocompatibility after being implanted into the dorsal muscle and the femoral shaft of the New Zealand rabbit, respectively, and there are no abnormalities after short-term implantation. In vivo observation indicated that the corrosion rate of this alloy varies with different implantation positions, with higher degradation rate in the femur than in the muscle.     

Ti – Cu– Zr–Fe– Nb ultrafine structur e-dendrite composites with good mechanical properties and biocompat ibility

Ti-Cu-Zr-Fe-Nb ultrafine structure-dendrite composites were designed by inducing Nb and more Ti to a Ti-Cu-Zr-Fe glass-forming alloy composition and prepared by copper mold casting.The composite alloys consist of β-Ti dendrites and ultrafine-structured CuTi₂ and CuTi phases as well as a trace amount of glassy phase.The volume fraction of β-Ti dendrites increases with the increase in content of Nb which acted as the β-Ti phase stabilizer in the alloys.The composites exhibit high compressive yield strength exceeding1200 MPa,maximum strength around 1800 MPa and low Young’s modulus around 48 GPa.The plasticity of the alloys is strongly influenced by the volume fraction and morphology of the dendritic β-Ti phase,and the compressive plastic strain was enlarged from 5.9%for the 4 at%Nb alloy to 9.2%for the 8 at%Nb alloy.The preliminary cell culture experiment indicated good biocompatibility of the composite alloys free from highly toxic elements Ni and Be.These Ti-based composite alloys are promising to have potential structural and biomedical applications due to the combination of good mechanical properties and biocompatibility.     

CF-PMMA复合材料人工颅骨板的研制

本文研究了一种用于颅骨修补的CF-PMMA复合材料人工颅骨板.经动物实验和临床应用,证明该材料具有有机玻璃的优点,且不易脆裂、耐老化、耐冲击、线膨胀系数小。术后头颅超声波、摄片、CT,MRI等检查均无影响。生物相容性好,不致癌,手术操作方便,四年来临床应用近百例,效果良好.     

Co-doping of hydroxyapatite with zinc and fl uoride improves mechanical and biological properties of hydroxyapatite

Hydroxyapatite(HA) co-doped with Zn2+ tand F- ions was synthesized by precipitation method for the first time in this study.FTIR spectroscopy revealed Zn2+ tand F ions incorporation into HA structure.Co-doping of Zn2+ tand F- ions decreased unit cell volume of HA and decreased grain sizes.Zn2+ tor 5 mol% F addition into HA significantly improved its density.Microhardness was increased with Zn2+ taddition and further increase was detected with F co-doping.Zn2+ tand F co-doped samples had higher fracture toughness than pure HA.Zn2+ tincorporation to the structure resulted in an increase in cell proliferation and ALP activity of cells,and further increase was observed with 1 mol%F addition.With superior mechanical properties and biological response 2Zn1 F is a good candidate for biomedical applications.     

In vivo assessment of hepatotoxicity,nephrotoxicity and biodistribution using 3-aminopropyltriethoxysilane-coated magnetic nanoparticles （APTS-MNPs） in ICR mice

The biocompatibility and biodistribution of magnetic nanoparticles （MNPs） in vivo are essential to ensure their safely clinical application. We have studied these aspects with our 3-aminopropyltriethoxysilane-coated magnetic nanoparticles （APTS-MNPs） formulation, which can be used as magnetic induction hyperthermia media. Changes in tissue iron levels were analyzed after intraperitoneal injection of APTS-MNPs to ICR mice. Liver and kidney functions were tested. Heart, liver, spleen, lung, kidney, testis, and brain were sectioned for pathological analysis. Biodistribution of iron in various body tissues changed with time but greater fraction of the injected iron localized in the liver and spleen than in other tissues. Serum showed an increase in AST and LDH fol-lowing APTS-MNPs injection. Histological analyses of selected tissues showed no obvious abnormal changes. In conclusion, APTS-MNPs did not cause continuing changes in the liver and kidney function and thus can be safely used for in vivo application.     

Corrosion of magnesium and magnesium –calcium alloy in biologically-simulated environment

A study of biocompatibility and corrosion of both metallic magnesium(Mg) and a magnesium alloy containing 1% calcium(Mg–Ca) were investigated in in vitro culture conditions with and without the presence of bone marrow derived human mesenchymal stem cells(h MSCs).Chemical analysis of the degraded samples was performed using XRD and FEGSEM. The results from the XRD analysis strongly suggested that crystalline phase of magnesium carbonate was present on the surface of both the Mg and Mg–Ca samples. Flame absorption spectrometry was used to analyse the release of magnesium and calcium ions into the cell culture medium. Magnesium concentration was kept consistently at a level ranging from 40 to 80 m M for both Mg and Mg–Ca samples. No cell growth was observed when in direct contact with the metals apart from a few cells observed at the bottom of culture plate containing Mg–Ca alloy. In general, in vitro study of corrosion of Mg–Ca in a biologicallysimulated environment using cell culture medium with the presence of h MSCs demonstrated close resemblances to in vivo corrosion. Although in vitro corrosion of Mg–Ca revealed slow corrosion rate and no immediate cytotoxicity effects to h MSCs, its corrosion rate was still too high to achieve normal stem cell growth when cells and alloys were cultured in vitro in direct contact.     

Engineered polycaprolactone – magnesium hybrid biodegradable porous scaffold for bone tissue engineering

In this paper, we describe the fabrication of a new biodegradable porous scaffold composed of polycaprolactone(PCL) and magnesium(Mg)micro-particles. The compressive modulus of PCL porous scaffold was increased to at least 150% by incorporating 29% Mg particles with the porosity of 74% using Micro-CT analysis. Surprisingly, the compressive modulus of this scaffold was further increased to at least 236% when the silane-coupled Mg particles were added. In terms of cell viability, the scaffold modified with Mg particles significantly convinced the attachment and growth of osteoblasts as compared with the pure PCL scaffold. In addition, the hybrid scaffold was able to attract the formation of apatite layer over its surface after 7 days of immersion in normal culture medium, whereas it was not observed on the pure PCL scaffold. This in vitro result indicated the enhanced bioactivity of the modified scaffold. Moreover, enhanced bone forming ability was also observed in the rat model after 3 months of implantation. Though bony in-growth was found in all the implanted scaffolds. High volume of new bone formation could be found in the Mg/PCL hybrid scaffolds when compared to the pure PCL scaffold. Both pure PCL and Mg/PCL hybrid scaffolds were degraded after 3 months. However, no tissue inflammation was observed. In conclusion, these promising results suggested that the incorporation of Mg micro-particles into PCL porous scaffold could significantly enhance its mechanical and biological properties. This modified porous bio-scaffold may potentially apply in the surgical management of large bone defect fixation.     

Antibac terial and biocom patible properties of vancomycin-loaded nano hydroxyapatite/collag en/poly (lactic acid) bone substitute

Infected bone defects are normally regarded as contraindications for bone grafting.In the present study,an antibacterial bone graft substitute was synthesized by loading vancomycin(VCM) in our previously developed mineralized collagen based composite,nano-hydroxyapatite/collagen/poly(lactic acid)(nHAC/PLA),aiming to repair large size bone defects and inhibit related infections simultaneously.The VCM/nHAC/PLA showed typical porous structure with a porosity of(80.7± 6.7)%and compressive strength of 1.52 MPa.The delivery of VCM from VCM/nHAC/PLA was detected in vitro for up to 4weeks.And their antibacterial properties were determined using inhibition ratio assay and inhibition zone assay.Pretty high level of inhibition ratio(more than 99%) was obtained in VCM/nHAC/PLA group.Additionally,a distinct inhibition zone was clearly formed in Staphylococcus aureus bacterium incubation dish with VCM/nHAC/PLA disc for up to 18 days of incubation.Moreover,both of the nHAC/PLA composites with or without VCM exhibited favorable in vitro and in vivo biocompatibilities for rabbit marrow stromal cells(MSCs) adhesion,spreading,proliferation,and triggering no obvious inflammation responses in subcutaneous implantation.Our results suggested that the VCM/nHAC/PLA performed ideal antibacterial property and biocompatibility and has great promise for the treatment of bone defect-related infections in orthopedic surgeries.