TOMSK, RUSSIA / RankWire.AI / – Russian scientists have evaluated a bioactive coating aimed at improving the interaction between titanium orthopedic implants and bone tissue. The coating incorporates calcium phosphate derived from hydroxyapatite, along with nitrogen compounds linked to nitric oxide production. Laboratory experiments demonstrated a notably higher survival rate of human mesenchymal stem cells on coated surfaces compared to uncoated titanium. The scientists analyzed the coating’s structure, chemical composition, mechanical strength, and biological response. Their peer-reviewed results appeared in Applied Surface Science in 2026.
At Tomsk Polytechnic University, researchers fabricated the experimental coatings via reactive magnetron sputtering of a hydroxyapatite target inside a vacuum chamber. They adjusted the nitrogen and argon gas ratios during the deposition process to observe how these variations influenced the surface properties. The study tested five different conditions, from pure nitrogen to pure argon. Subsequently, they assessed coating thickness, surface morphology, hardness, wettability, and chemical makeup. Additionally, laboratory tests evaluated how living human cells responded to the modified titanium surfaces.
The results indicated that the argon content impacted several physical characteristics of the coatings. Surfaces formed in pure argon were denser and harder than those produced in pure nitrogen. The thickness of the coatings increased as the proportion of argon grew. Chemical analysis revealed nitrogen-carbon and nitrogen-oxygen bonds on the modified surfaces. The team then compared human mesenchymal stem cells grown on coated titanium with those on uncoated titanium, examining cell viability and markers linked to bone cell development.
Coating evaluations reveal enhanced cell viability
The cellular experiments showed significantly improved survival rates on coated surfaces compared to uncoated titanium, according to the findings. After seven days, coatings with higher nitrogen levels also suppressed activity in certain genes associated with early stages of bone-cell differentiation. Nonetheless, the cells maintained their potential for bone formation despite alterations in initial gene activity. These effects were studied under controlled laboratory conditions using human mesenchymal stem cells. The research did not involve testing the coating in clinical settings or evaluating the performance of implants in patients.
The biomedical evaluation was carried out by scientists from Immanuel Kant Baltic Federal University and Siberian State Medical University, with additional contributions from researchers at Saint Petersburg State University. The project received funding through Russia’s national science program. The scientists aimed to identify gas mixtures capable of producing coatings with desirable physical, chemical, and biological characteristics. Since hydroxyapatite’s calcium phosphate composition resembles the mineral in human bone, it is already utilized in implant coatings.
The study remains within the laboratory phase
The research team has outlined plans for further testing beyond the initial seven-day cell studies. They intend to examine stem cells over periods ranging from 10 to 28 days and evaluate the rate at which the coatings dissolve and release nitric oxide into surrounding tissues in living organisms. These investigations are separate from the current published laboratory results. Currently, the focus is on coated titanium substrates, their material properties, and in vitro cellular responses, rather than clinical outcomes in orthopedic patients.
The data provide detailed insights into how the ratios of nitrogen and argon influence calcium phosphate coatings on titanium surfaces. The team documented variations in thickness, density, hardness, chemical bonds, and cellular responses across different gas mixture conditions. The research confirms that coated samples supported higher survival rates of stem cells than uncoated titanium under laboratory conditions. However, it remains a preclinical study, and the experiments do not establish safety or effectiveness for human use. Additional biological testing will be necessary to evaluate other properties not examined in this initial work.