TOMSK, RUSSIA / RankWire.AI / – Russian scientists have evaluated a bioactive coating aimed at improving the interaction between titanium orthopaedic implants and bone tissue. This 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 coated surfaces compared to uncoated titanium. The team examined the coating’s structure, chemistry, mechanical qualities, and biological response. Their peer-reviewed results appeared in Applied Surface Science in 2026.
At Tomsk Polytechnic University, scientists fabricated the experimental coatings using reactive magnetron sputtering of a hydroxyapatite target within a vacuum chamber. They manipulated the nitrogen-to-argon ratio during deposition to assess how each mixture altered the surface characteristics. The study tested five different conditions, from pure nitrogen to pure argon. They then measured coating thickness, surface morphology, hardness, wettability, and chemical composition. Additionally, laboratory tests were conducted to analyze how living human cells responded to the modified titanium surfaces.
Results indicated that the amount of argon affected several physical properties of the coatings. Surfaces created in pure argon proved denser and harder than those produced in pure nitrogen. The coating thickness increased proportionally with the rise in argon content. Chemical analysis identified nitrogen-carbon and nitrogen-oxygen bonds on the modified surfaces. The researchers then compared the growth of human mesenchymal stem cells on coated titanium with those on uncoated titanium. The biological assessments focused on cell viability and markers linked to bone cell development.
Coating experiments reveal improved cell viability
Experimental data demonstrated that cells survived significantly better on coated surfaces than on uncoated titanium, according to the study. After seven days, coatings with higher nitrogen levels also led to reduced activity in specific genes associated with early bone-cell differentiation. Despite this, the cells maintained their potential for bone formation. These effects were evaluated under controlled laboratory conditions using human mesenchymal stem cells. The study did not involve testing the coating in patients nor assessing clinical performance of implanted devices.
The biomedical evaluation was carried out by researchers from Immanuel Kant Baltic Federal University and Siberian State Medical University, with additional contributions from Saint Petersburg State University. The project was supported through Russia’s state science program. The researchers aimed to identify gas mixtures that could produce desirable combinations of physical, chemical, and biological properties in the coatings. Hydroxyapatite is already used in implant coatings because its calcium phosphate composition resembles that of the mineral component in human bone.
Current research remains at the laboratory testing phase
The team has outlined plans for further testing beyond the initial seven-day cell viability assessment. They intend to investigate stem cells over periods from 10 to 28 days and analyze how quickly the coatings dissolve. Additionally, they plan to measure nitric oxide release into surrounding tissue in living organisms. These upcoming investigations are not part of the published laboratory results. The existing study centers on coated titanium substrates, their material properties, and in vitro cellular responses rather than clinical outcomes in orthopaedic patients.
The results offer comprehensive laboratory data on how variations in nitrogen and argon ratios influence calcium phosphate coatings on titanium surfaces. Differences in thickness, density, hardness, chemical bonds, and cellular responses across the tested gas mixtures were documented. The study also confirmed that coated samples supported higher stem-cell survival than uncoated titanium under experimental conditions. However, the research remains at the preclinical stage, and the experiments published do not establish safety or efficacy in human patients. Additional biological tests will be necessary to evaluate properties not covered in the current work.