gh A FILM TO PROTECT IMPLANTS

Implants that replace bones and joints experience significant load and wear out quickly. They can be protected by covering by a special film. New bioactive ceramic films containing tantalum are being developed by specialists of the Moscow Institute of Steel and Alloys (State Technological University), the N.N. Blokhin Cancer Research Center (Russian Academy of Medical Sciences) and the Colorado School of Mines (USA).

The first films developed by the researchers were based on titanium carbonitride. The next-generation films contain tantalum. This metal is extensively used in reconstructive surgery primarily due to its high durability and solidity, which combine with excellent plastic characteristics, high chemical resistance and biological compatibility. In terms of corrosion stability and wear-resistant, tantalum carbides and nitrides are more stable than similar compounds of other transition metals.

Multi-component films were obtained by dispersing titanium and tantalum carbides with calcium oxides or phosphates in the argon or argon/nitrogen gas mixture atmosphere. The VT1-0 type titanium, single-crystalline silicon, stainless steel and cover glass were used as an undercoat for sputtering.

A human organism is a rather aggressive environment. The films are to experience significant mechanical load, including friction, electrolyte influence, and interaction with cells. Initial laboratory tests have proved that the film wear rate upon friction in the open air and in the physiological solution turned out to be lower by two orders than that of titanium. The new material is less subjected to corrosion that the films without tantalum.

The tantalum-containing films have successfully passed the first biocompatibility tests. The undercoats covered by the films were placed in the nutrient medium and populated by epithelial and osteoblast cells – the cells that form osseous tissues. The cells felt very well and reproduced much more actively on the surface of tantalum-containing protective films that on the glass that was used for reference. The researchers made sure that the osseous tissue will be able to generate upon the protective films surface. In the researchers’ opinion, multi-purpose tantalum-containing nanostructural films are a promising material for creation of implants to be working under load.

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