It has been revealed that the different morphologies of anodized TiO_2 nanotubes, especially nanotube diameters, triggered different cell behaviors. However, the influence of TiO_2 nanotubes with coexisting multi-size diameters on cell behaviors is seldom reported. In this work, coexisting four-diameter TiO_2 nanotube samples, namely,one single substrate with the integration of four different nanotube diameters(60, 150, 250, and 350 nm), were prepared by repeated anodization. The boundaries between two different diameter regions show well-organized structure without obvious difference in height. The adhesion behaviors of MC3T3-E1 cells on the coexisting fourdiameter TiO_2 nanotube arrays were investigated. The results exhibit a significant difference of cell density between smaller diameters(60 and 150 nm) and larger diameters(250 and 350 nm) within 24 h incubation with the coexistence of different diameters, which is totally different from that on the single-diameter TiO_2 nanotube arrays. The coexistence of four different diameters does not change greatly the cell morphologies compared with the singlediameter nanotubes. The findings in this work are expected to offer further understanding of the interaction between cells and materials.
Surgical staples made of pure titanium and titanium alloys are widely used in gastrointestinal anastomosis.However the Ti staple cannot be absorbed in human body and produce artifacts on computed tomography(CT)and other imaging examination,and cause the risk of incorrect diagnosis.The bioabsorbable staple made from polymers that can degrade in human body environment,is an alternative.In the present study,biodegradable high purity magnesium staples were developed for gastric anastomosis.U-shape staples with two different interior angles,namely original 90and modified 100,were designed.Finite element analysis(FEA)showed that the residual stress concentrated on the arc part when the original staple was closed to B-shape,while it concentrated on the feet for the modified staple after closure.The in vitro tests indicated that the arc part of the original staple ruptured firstly after 7 days immersion,whereas the modified one kept intact,demonstrating residual stress greatly affected the corrosion behavior of the HP-Mg staples.The in vivo implantation showed good biocompatibility of the modified Mg staples,without inflammatory reaction 9 weeks post-operation.The Mg staples kept good closure to the Anastomosis,no leaking and bleeding were found,and the staples exhibited no fracture or severe corrosion cracks during the degradation.
