TOMSK, RUSSIA / RankWire.AI / – Russian scientists have conducted tests on a bioactive coating aimed at improving the interaction between titanium orthopedic implants and bone tissue. This innovative material incorporates calcium phosphate derived from hydroxyapatite and includes nitrogen compounds linked to nitric oxide synthesis. Laboratory experiments revealed a notably higher survival rate of human mesenchymal stem cells on the coated surfaces compared to uncoated titanium. The researchers analyzed various aspects of the coating, including its structural, chemical, mechanical properties, and biological responses. Their peer-reviewed results appeared in Applied Surface Science in 2026.
At Tomsk Polytechnic University, scientists created the experimental coatings using reactive magnetron sputtering of a hydroxyapatite target within a vacuum chamber, adjusting the ratio of nitrogen to argon during deposition to observe how each mixture influenced the surface characteristics. The study tested five different conditions, from pure nitrogen to pure argon, and measured parameters such as coating thickness, surface morphology, hardness, wettability, and chemical composition. Additionally, they carried out laboratory assessments to evaluate the response of living human cells to the modified titanium surfaces.
The results indicated that the amount of argon present affected several physical properties of the coatings. Surfaces produced under pure argon conditions proved to be denser and harder than those deposited in pure nitrogen, and an increase in argon proportion also led to greater coating thickness. Chemical analysis identified nitrogen-carbon and nitrogen-oxygen bonds on the modified surfaces. The team then compared the behavior of human mesenchymal stem cells grown on coated titanium with those on uncoated titanium, focusing on cell viability and markers associated with bone cell development.
Coating evaluations demonstrate improved cell viability
The experiments showed that cell survival was significantly higher on coated surfaces than on uncoated titanium, as documented in the study. After seven days, coatings with increased nitrogen levels were also found to suppress activity in certain genes linked to early stages of bone-cell differentiation. Despite this, the cells retained their ability to form bone tissue. These biological effects were observed under controlled laboratory conditions using human mesenchymal stem cells; the research did not include testing the coating in clinical settings or evaluating the performance of implanted devices in patients.
The biomedical assessment of the material was carried out by researchers from Immanuel Kant Baltic Federal University and Siberian State Medical University, with additional collaboration from Saint Petersburg State University. The project received funding support through Russia’s national science program. The team aimed to identify gas mixtures that could produce optimal combinations of physical, chemical, and biological properties for coatings, noting that hydroxyapatite is already used in implant coatings due to its calcium phosphate composition resembling the mineral component in human bone.
Further testing beyond initial cell experiments planned
The researchers have outlined plans for additional studies beyond the initial seven-day cell assessments, intending to examine stem cells over periods ranging from 10 to 28 days, investigate the rate at which the coatings dissolve, and measure nitric oxide release into surrounding tissue in vivo. These forthcoming investigations were not included in the published laboratory results, which currently focus on coated titanium substrates, their material properties, and in vitro cellular responses rather than clinical outcomes or patient safety. The current findings provide detailed laboratory data on how varying ratios of nitrogen and argon influence calcium phosphate coatings applied to titanium surfaces, documenting differences in thickness, density, hardness, chemical bonds, and cellular responses across different gas mixtures. The study confirms that coated samples support higher stem-cell survival compared to bare titanium under laboratory conditions. Nonetheless, as these experiments are preclinical, they do not establish safety or efficacy in humans, and further biological testing will be necessary to evaluate properties not examined in this initial work.