[Evaluation of osseointegration of domestic porous tantalum-niobium alloy].

PURPOSE: To evaluate the osseointegration of domestic porous tantalum-niobium(PTa-Nb) alloy. METHODS: A total of 36 adult New Zealand rabbits were selected and divided into 3 groups. Pta-Nb rods(3.5 mm×10 mm) were implanted into the femoral condyle of each rabbit.The rabbits were sacrificed successively at 4,8,12 weeks after operation. X-ray, hard tissue slices stained with toluidine blue, scanning electron microscope(SEM), X-ray energy disperse spectroscopy(XEDS) and push-out test were used to test the osseointegration of PTa-Nb. SPSS19.0 software package was used for statistical analysis. RESULTS: X-ray films showed no obvious inflammation,as well as implants loosing and bone resorption. Density of the bone around implants increased. Hard tissue slices displayed chimeric shape in the implant-bone interface. New bone contacted directly to the surface of PTa-Nb and got more and more closer with the increase of healing time. Osteoid formed in the inner pores at 4 weeks after operation,and more mature bone tissue grew into inner part of PTa-Nb at 12 weeks. SEM showed bone tissue was more denser and closer to the Pta-Nb,which was similar to the results of hard tissue slices. XEDS analysis showed the percent content of the calcium and phosphate of the tissue within PTa-Nb increased gradually in the three groups.The ratio of Ca/P at 8 and 12 weeks was significantly higher than at 4 weeks (P<0.05); Push-out test showed the shear-strength of PTa-Nb implants increased from (8.26±0.75) MPa at 4 weeks to (21.04±1.46) MPa at 12 weeks (P<0.05). CONCLUSIONS: The domestic PTa-Nb alloy has good osseointegration with both bone tissue ongrowth and ingrowth,which may be a high potential biomimetic bone material.

[Silica nanoparticles modified as carriers for gene transfection].

The silica nanoparticles are modified by sodium iodine or sodium chloride with different concentration. Their ability to bind and protect plasmid DNA was demonstrated by agarose gel electrophoresis. The EGFP-N1 plasmid was transfected into HT1080 by combing silica nanoparticle. Eletromicroscope examine revealed that nanoparticle-DNA could enter into cells, these silica nanoparticles protect DNA against nuclease digestion and the GFP has an effective expression. In conclusion, these nanoparticles might be used as DNA carriers for gene transfection.