silicon and nitinol

Cryo-electron microscopy (cryoEM) has become one of the most important approach for structural biology. However, barriers are still there for an increased successful rate, a better resolution and improved efficiency from sample preparation, data collection to image processing. CryoEM sample preparation is one of the bottlenecks with many efforts made recently, including the optimization of supporting substrate (e.g. ultra-thin carbon, graphene, pure gold, 2d crystal of streptavidin, and affinity modification), which was aimed to solve air-water interface problem, or reduce beam induced motion (BIM), or change particle distribution in the grid hole. Here, we report another effort of developing a new supporting substrate, the amorphous nickel-titanium alloy (ANTA) film, for cryoEM sample preparation as a layer of holey supporting film covering on TEM grid. Our investigations showed advantages of ANTA film in comparison with conventional carbon film, including much better electron conductivity and trace non-specific interaction with protein. These advantages yield less BIM and significantly improved particle distribution during cryoEM experiment of human apo-ferritn, thus resulting an improved reconstruction resolution from a reduced number of micrographs and particles. Unlike the pure gold film, the usage of the ANTA film is just same with the carbon film, compatible to conventional automatic cryoEM data collection procedure.

Topics: Alloys; Animals; Apoferritins; B7-H1 Antigen; Biocompatible Materials; Biotinylation; Carbon; Cryoelectron Microscopy; Gold; Hippocampus; Humans; Ligands; Magnetic Fields; Materials Testing; Microscopy, Atomic Force; Microscopy, Electron, Transmission; Motion; Neurons; Nickel; Protein Binding; Rats; Rats, Sprague-Dawley; Silicon; Streptavidin; Temperature; Titanium

Bone regeneration by periosteal distraction has been reported in numerous animal studies; however, the main disadvantages of this technique are poor bone quality and soft tissue invasion in the distracted space. The purpose of this study was to evaluate a novel shape memory-based device to promote bone regeneration in a large, secluded growth space in a rabbit model. Twenty rabbits were divided into two groups. In the first group (n = 10), a device composed of silicone sheets and nitinol strips was inserted subperiosteally in the calvarial area. In the second group (n = 10), only silicone sheets were inserted in the calvarial area. Each group was further divided in half: five animals were sacrificed at 8 weeks postoperatively, and the other five were sacrificed at 16 weeks postoperatively. In the study group, the new device vertically expanded the overlying soft tissue 4 mm above the original bone and created a secluded space; the newly generated bone maximum height median ranged between 2.7 mm in 8 weeks group and 2.6 mm in 16 weeks group. In the control group, a very thin rim of bone was generated below the flat silicone sheets on top of the original bone. Maximum bone heights median ranged from 0.37 mm in 8 weeks group to 0.32 mm in 16 weeks group. The device was proven to be effective at vertically augmenting bone by applying the guided bone regeneration and soft tissue expansion procedures simultaneously. This device may pave the way for a new generation of smart guided bone regeneration membranes that can remember the original dimensions of resorbed bone areas.

Topics: Alloys; Animals; Bone Regeneration; Equipment and Supplies; Guided Tissue Regeneration; Humans; Male; Models, Animal; Osteogenesis; Osteogenesis, Distraction; Prosthesis Implantation; Rabbits; Silicon; Skull; Time Factors

In order to improve the surface bioactivity of NiTi bone implant and corrosion resistance, hydroxyapatite coating with addition of 20wt% silicon, 1wt% multi walled carbon nano-tubes and both of them were deposited on a NiTi substrate using a cathodic electrophoretic method. The apatite formation ability was estimated using immersion test in the simulated body fluid for 10days. The SEM images of the surface of coatings after immersion in simulated body fluid show that the presence of silicon in the hydroxyapatite coatings accelerates in vitro growth of apatite layer on the coatings. The Open-circuit potential and electrochemical impedance spectroscopy were measured to evaluate the electrochemical behavior of the coatings in the simulated body fluid at 37°C. The results indicate that the compact structure of hydroxyapatite-20wt% silicon and hydroxyapatite-20wt% silicon-1wt% multi walled carbon nano-tubes coatings could efficiently increase the corrosion resistance of NiTi substrate.

Topics: Alloys; Body Fluids; Coated Materials, Biocompatible; Durapatite; Humans; Nanotubes, Carbon; Silicon

The hemocompatibility of plasma-treated, silicon-incorporated, diamond-like carbon (Si-DLC) films was investigated. Si-DLC films with a Si concentration of 2at.% were prepared on Si (100) or Nitinol substrates using a capacitively coupled radiofrequency plasma-assisted chemical vapor deposition method using a mixed gas of benzene (C(6)H(6)) and diluted silane (SiH(4):H(2)=10:90). The Si-DLC films were then treated with O(2), CF(4) or N(2) glow discharge for surface modification. The plasma treatment revealed an intimate relationship between the polar component of the surface energy and its hemocompatibility. All in vitro characterizations, i.e. protein absorption behavior, activated partial thromboplastin time measurement and platelet adhesion behavior, showed improved hemocompatibility of the N(2-)- or O(2)-plasma-treated surfaces where the polar component of the surface energy was significantly increased. Si-O or Si-N surface bonds played an important role in improving hemocompatibility, as observed in a model experiment. These results support the importance of a negatively charged polar component of the surface in inhibiting fibrinogen adsorption and platelet adhesion.

Topics: Adsorption; Albumins; Alloys; Carbon; Diamond; Humans; Models, Statistical; Nitrogen; Oxygen; Partial Thromboplastin Time; Platelet Adhesiveness; Silicon; Surface Properties; Time Factors; Water

Topics: Alloys; Aorta; Humans; Prosthesis Implantation; Silicon; Silicones; Stents; Trachea; Transplantation, Autologous; Transplantation, Heterotopic