This study aims to look into the applicability of a porous TiNi-based shape memory alloy (SMA) scaffold as an incubator for bone marrow mesenchymal cells, hepatocytes, and pancreatic islet cells. The porous TiNi-based SMA used was fabricated using a self-propagating high-temperature synthesis (SHS) technique, in which scaffold blocks measuring 4 × 4 × 10 mm were prepared. In vitro tests were done using mesenchymal stem cells (MSC) isolated from mature bone marrow of CBA/j inbred mice, and cultured in 3 different culture media - Control medium, Osteogenic medium, and Chondrogenic medium. Hepatocytes and islet cells were isolated from the livers and pancreatic glands of Wistar rats respectively, seeded on porous TiNi-based SMA scaffolds, and cultured. The scaffolds were then implanted into the abdominal cavity of Wistar rats and later harvested, at days 7, 14, 21, and 28, post-implantation. SEM imaging was performed with pre-implanted scaffolds at day 0 and harvested scaffolds at days 7, 14, 21, and 28, post-implantation. Based on weight increase percentages, the in vitro study revealed that the osteogenic group showed a 2-fold increase, and the chondrogenic group showed a 1.33-fold increase, compared to the control group. The in vivo study, on the other hand, showed that from day 7 post-implantation, the cellular in-growth gradually invaded the inner porous structure from the periphery towards the center, and at day-28 post-implantation, all pores were closed and completely filled with cells and the extracellular matrix. The results show that porous TiNi-based SMA is a unique biocompatible incubator for cell cultures and can be successfully used for tissue bioengineering and artificial organs.

Coatings based on calcium phosphate with thicknesses of 0.5 and 2 μm were obtained by high-frequency magnetron sputtering on NiTi substrates in an argon atmosphere. The coating was characterized using X-ray diffraction, scanning electron microscopy, atomic force microscopy, and in vitro cytocompatibility and bioactivity studies. A biphasic coating of tricalcium phosphate (Ca₃(PO₄)₂) and hydroxyapatite (Ca₁₀(PO₄)₆(OH)₂) with a 100% degree of crystallinity was formed on the surface. The layer enriched in calcium, phosphorus, and oxygen was observed using scanning electron microscopy and energy-dispersive X-ray spectroscopy. Scanning electron microscopy showed that the surface structure is homogeneous without visible defects. The 2 µm thick coating obtained by sputtering with a deposition time of 4 h and a deposition rate of 0.43 µm/h is uniform, contains the highest amount of the calcium phosphate phase, and is most suitable for the faster growth of cells and accelerated formation of apatite layers. Samples with calcium phosphate coatings do not cause hemolysis and have a low cytotoxicity index. The results of immersion in a solution simulating body fluid show that NiTi with the biphasic coating promotes apatite growth, which is beneficial for biological activity.

A new approach to fabricate TiNi surfaces combining the advantages of both monolithic and porous materials for implants is used in this work. New materials were obtained by depositing a porous TiNi powder onto monolithic TiNi plates followed by sintering at 1200 °C. Then, further modification of the material surface with a high-current-pulsed electron beam (HCPEB) was carried out. Three materials obtained (one after sintering and two after subsequent beam treatment by 30 pulses with different pulse energy) were studied by XRD, SEM, EDX, surface profilometry, and by means of electrochemical measurements, including OCP and EIS. Structural and compositional changes caused by HCPEB treatment were investigated. Surface properties of the samples during their storage in saline for 10 days were studied and a model experiment with cell growth (MCF-7) was carried out for the unmodified sample with an electron beam to detect cell appearance on different surface locations.

The present work is aimed at studying the surface cytocompatibility of porous NiTi obtained by self-propagating high temperature synthesis (SHS), and then annealed in air at 500–1000 °C. Using cytotoxicity tests in vitro, it was found that the cells had attached to the oxidized surface in the amount sufficient for their growth and proliferation on the substrate. The surfaces of the annealed samples and the control sample were studied by XRD, SEM and optical microscopy. It was found that there is a correlation between cell hemolysis and nickel-containing phases on the surface. Thus, annealing at 500–700 °C worsens cytocompatibility compared to the control sample, but annealing at 800–1000 °C improves cytocompatibility.

This work aims to study the cytocompatibility of protective coatings obtained in argon and nitrogen atmospheres on a TiNi surface. Particular attention is paid to comparing the interaction of cell culture with coatings and an uncoated TiNi sample, using for comparison the number of viable cells on the surface, the phase composition, structure, wettability, surface charge and topography. The Ti/Ni/Ti nanolaminate was deposited on a TiNi substrate by magnetron sputtering. Reaction annealing of Ti/Ni/Ti nanolaminate on a TiNi substrate, when heated to 900 °C in argon, leads to the formation of a dense two-layer coating 2.0–2.1 μm thick: layer I (TiO + Ti₂N), layer II (Ti₄Ni₂ O(N)). Reaction annealing in nitrogen leads to the formation of a thin three-layer nanocoating 250 nm thick: I (TiO₂ + TiN), II (Ti₄Ni₂N(O) + Ti₃Ni₄), III (TiN). The coating synthesized in nitrogen is more favorable for cell attachment and proliferation because of the moderately hydrophilic rough surface and mixed phase composition of titanium nitrides and oxides.