[Comparison of surface characteristics and cytocompatibility of Ti-6Al-4V alloy fabricated with select laser melting and electron beam melting].

Objective: To evaluate the surface characteristics and cytocompatibility of Ti-6Al-4V alloy fabricated using select laser melting (SLM) and electron beam melting (EBM) technique. Methods: Ti-6Al-4V alloy specimens were fabricated with SLM and EBM. A wrought form of Ti-6Al-4V alloy was used as a control. Its properties were evaluated using component analysis, contact angle test, surface roughness, surface topography, cell ultrastructure, cell attachment and proliferation observation, metal ion precipitation examination. Results: The roughness of SLM and EBM specimens was suitable for cell attachment but not the best. The character of SLM and EBM specimens was hydrophobic (>65°). The surface topography of EBM and SLM specimens were similar, but were not the best type for cell attachment. The components of Ti-alloy oxide film were detected in all the specimens. The content of Ti, Al, V ions of EBM, SLM and wrought specimens were very low and did not affect the cell attachment and proliferation. The ultrastructure of cell was normal, and the cytomembrane was intact. The number of cells was similar to each other among the three kinds of specimens and increased obviously with the culture time. Conclusions: The results of the study suggested that EBM and SLM Ti-6Al-4V specimens possessed good surface characteristics. However, the surface modification are needed further.

[A preliminary study on the mechanical characteristics of the titanium scaffolds with three-dimensional mesh structure fabricated by electron beam melting].

Objective: To examine the biomechanical properties of three-dimensional(3D) printed electron beam melting(EBM) Ti-6Al-4V mesh as scaffold for mandibular repairment. Methods: We fabricated Ti-6Al-4V samples of different structures with strut, sheet and 3D mesh scaffolds(a controllable diameter 0.35, 0.50, 0.70 mm, distribution density: intensive sparse) by EBM process. The mechanical properties of these structures were examined by X-ray energy dispersive spectrum(EDS), uniaxial tensile test, three-point bending test, under compression load and compared with their different microstructure and mechanical properties. Results: Compressive deformation behavior of these cellular structures exhibited brittle character that had a typical irregular plateau region in the stress-strain curves. The mesh of larger diameter(d=0.70 mm) showed higher specific strength than the meshs of small diameter(d=0.35 mm) did, and the other 3D mesh under the same condition showed identical specific stiffness. Conclusions: EBM was successfully used to fabricate novel 3D mesh Ti-6Al-4V structures for applications. By optimizing the buckling and bending deformation, Ti-6Al-4V cellular solids with high strength, low modulus. Furthermore, the results of mechanical property and chemistry composition showed that the scaffold could completely satisfy the requirement of hard tissue repairment.

[Evaluation of biocompatibility of Ti-6Al-4V scaffolds fabricated by electron beam melting].

Objective: To investigate the biocompatibility of Ti-6Al-4V scaffolds fabricated by electron beam melting(EBM). Methods: Bone marrow mesenchymal stem cells(BMSC) co-cultured with Ti-6Al-4V specimens fabricated with EBM was prepared as experimental group and the regular cells culture was employed as control. The biocompatibility was detected using CCK-8 and cytoskeleton staining. The osteogenic differentiation ability was assessed using mineralization nodule formation. A 24 mm defect was created on the right mandibular body in 12 beagles. The mandibular defects were repaired with Ti-6Al-4V scaffolds mesh fabricated by EBM. General observation, CT and histology examination was carried out to evaluated the biocompatibility of Ti-6Al-4V scaffolds in vivo. Results: CCK-8 result showed the A values of the two groups had no significant difference(P >0.05). There was no significant difference between the two groups (P>0.05). Cytoskeletal staining showed that cells were fully stretched out and grew well on T-i6Al-4V specimen. The actin fibers were arranged in parallel and stained uniformly with fluorescent. After osteogenic culture, the quantity of the nodule formation of the experimental group and control group were 5.7±0.7 and 5.1 ± 0.6, respectively(P>0.05). All animals had tolerated the surgery and healed well. CT examination showed that Ti-6Al-4V scaffolds mesh had good retention with surrounding bone and the continuity of mandible was restored. Histological examination showed that no inflammation reaction or toxity was caused in the soft tissue surrounding the scaffolds and in the liver and kidney after implantation. Ti-6Al-4V scaffolds had good retention with surrounding bone. Conclusions: Ti-6Al-4V fabricated with electron beam melting has good biocompatibility.

Synthesis and anti-HIV activity of novel 2,4-disubstituted-7-methyl-1,1,3-trioxo-2H,4H-pyrazolo[4,5-e][1,2,4]thiadiazine derivatives.

A series of novel 2,4-disubstituted-7-methyl-1,1,3-trioxo-2H,4H-pyrazolo[4,5-e][1,2,4]thiadiazines (PTDs) was prepared starting from a ring of pyrazolo[4,5-e][1,2,4]thiadiazine nuclei with two different alkyl halides obtained by a facile one-pot reaction. The structures of all synthesized compounds were confirmed by 1H- and 13C-NMR, infrared spectra (IR), and mass spectra (MS) spectroscopic analysis. Anti-HIV activity was evaluated and none of the compounds were found to inhibit HIV replication in human T-lymphocyte (MT-4) cell culture.