TOMSK, RUSSIA / RankWire.AI / – Russian scientists have developed and tested a bioactive coating aimed at optimizing the interaction between titanium orthopedic implants and bone tissue. The coating incorporates calcium phosphate derived from hydroxyapatite and nitrogen compounds linked to nitric oxide production. Laboratory experiments demonstrated a markedly higher survival rate of human mesenchymal stem cells on coated surfaces compared to uncoated titanium. The scientists analyzed the coating’s structural, chemical, mechanical, and biological properties. Their peer-reviewed results were published in Applied Surface Science in 2026.
At Tomsk Polytechnic University, researchers fabricated the experimental coatings via reactive magnetron sputtering of a hydroxyapatite target within a vacuum chamber. During deposition, they adjusted the nitrogen and argon gas mixture to observe how each variation influenced the surface characteristics. The study tested five different conditions, from pure nitrogen to pure argon. The team then evaluated coating thickness, surface morphology, hardness, wettability, and chemical composition. Additionally, laboratory tests examined the biological response of living human cells to the modified titanium surfaces.
Results indicated that the argon content significantly impacted various physical properties of the coatings. Surfaces formed in pure argon were denser and exhibited greater hardness than those created in pure nitrogen. An increase in argon proportion also led to thicker coatings. Chemical analysis revealed nitrogen-carbon and nitrogen-oxygen bonds present on the modified surfaces. The team then compared human mesenchymal stem cells grown on coated titanium to those on uncoated titanium, assessing cell viability and markers associated with bone cell development.
Enhanced Cell Survival Observed with Coated Implants
The cell experiments indicated a significant improvement in survival rates on coated surfaces relative to uncoated titanium, as reported in the study. After seven days, coatings with higher nitrogen content also suppressed the activity of certain genes linked to early bone-cell differentiation. Despite this change in gene activity, the cells maintained their ability to form bone tissue. The researchers conducted these tests under controlled laboratory conditions using human mesenchymal stem cells, noting that the study did not include clinical testing or real-world performance assessments of medical implants.
The biomedical evaluation was carried out by Immanuel Kant Baltic Federal University and Siberian State Medical University. Additional expertise was contributed by specialists from Saint Petersburg State University. The project was supported through Russia’s national science program. The researchers aimed to identify gas mixtures capable of producing coatings with optimal physical, chemical, and biological properties. Hydroxyapatite’s calcium phosphate composition is already utilized in implant coatings because it resembles the mineral component found in human bone.
Current research remains at the laboratory stage
The team has planned further testing beyond the initial seven-day cell viability assessment. They intend to study stem cell behavior over periods of 10 to 28 days, evaluate the dissolution rate of the coatings, and measure nitric oxide release into surrounding tissues in living organisms. These additional investigations are outside the scope of the current published results, which focus on coated titanium substrates, their physical and chemical properties, and biological responses in vitro, rather than clinical outcomes in orthopedic patients.
The data presented offer a detailed understanding of how nitrogen and argon ratios influence calcium phosphate coatings on titanium surfaces. Variations in thickness, density, hardness, chemical bonds, and cellular response across different gas mixtures were documented. Importantly, the findings also confirmed that coated samples supported higher stem-cell survival compared to uncoated titanium under laboratory conditions. Nevertheless, the research remains in the preclinical phase, and the experiments published do not establish safety or efficacy for human use. Future biological testing will address properties not examined in this study to ensure safety and performance.