TOMSK, RUSSIA / RankWire.AI / – Russian scientists have evaluated a bioactive surface treatment aimed at improving the interaction between titanium orthopedic implants and bone tissue. This coating incorporates calcium phosphate derived from hydroxyapatite and contains nitrogen-based compounds linked to nitric oxide production. Laboratory experiments revealed a notably higher survival rate of human mesenchymal stem cells on coated surfaces compared to uncoated titanium. The team analyzed the coating’s structural, chemical, mechanical, and biological characteristics. Their peer-reviewed results appeared in Applied Surface Science in 2026.
Researchers at Tomsk Polytechnic University manufactured the experimental coatings using reactive magnetron sputtering of a hydroxyapatite target within a vacuum chamber. They varied the nitrogen-to-argon ratio during deposition to observe how each mixture influenced the surface properties. Five different conditions were tested, from pure nitrogen to pure argon. The scientists measured parameters such as coating thickness, surface morphology, hardness, wettability, and chemical composition. Additionally, they conducted laboratory tests to observe how living human cells responded to the modified titanium surfaces.
The results indicated that the proportion of argon influenced several physical qualities of the coatings. Surfaces created in pure argon proved to be denser and harder than those formed in pure nitrogen. As the argon content increased, coating thickness also grew. Chemical analysis identified nitrogen-carbon and nitrogen-oxygen bonds on the modified surfaces. The team then compared the behavior of human mesenchymal stem cells cultured on coated titanium with cells on uncoated titanium. The biological testing focused on cell viability and markers associated with bone-cell development.
Enhanced cell survival observed in coating tests
The experiments demonstrated a significant increase in cell survival on coated surfaces versus uncoated titanium, according to the published findings. After a week, coatings with higher nitrogen levels also appeared to suppress activity in certain genes linked to early bone-cell differentiation. Despite this, the cells maintained their ability to form bone tissue. These assessments were carried out under controlled laboratory conditions using human mesenchymal stem cells, and the study did not involve testing in patients or evaluating the clinical performance of actual implants.
The biomedical evaluation of the material was carried out by Immanuel Kant Baltic Federal University and Siberian State Medical University, with additional participation 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 optimal combinations of physical, chemical, and biological properties in the coatings. Hydroxyapatite is already used in implant coatings due to its calcium phosphate composition, which resembles the mineral component of human bone.
Study remains in initial testing phase
The team has proposed further testing beyond the initial seven-day cell viability assessments. Planned future studies include examining stem cells over periods from 10 to 28 days, analyzing the rate at which the coatings dissolve, and measuring nitric oxide release into surrounding tissue in vivo. These aspects were not part of the current laboratory results. Presently, the focus remains on coated titanium substrates, their material properties, and in vitro biological responses, rather than clinical outcomes in orthopaedic patients.
The study provides detailed laboratory data on how varying nitrogen and argon ratios influence calcium phosphate coatings on titanium surfaces. The data demonstrate differences in coating thickness, density, hardness, chemical bonding, and cellular responses across different gas mixtures. Importantly, the results showed that coated samples supported higher stem-cell survival than bare titanium under experimental conditions. Nonetheless, the research is still in the preclinical stage, and the findings do not confirm safety or effectiveness in humans. Additional biological tests will be necessary to evaluate properties not addressed in this initial study.