Biocompatibility of new materials based on nano-structured nitinol with titanium and tantalum composite surface layers: experimental analysis in vitro and in vivo

A technology for obtaining materials from nanostructured nitinol with titanium- or tantalum-enriched surface layers was developed. Surface layers enriched with titanium or tantalum were shown to provide a decrease in the formation of reactive oxygen species and long-lived protein radicals in comparison to untreated nitinol. It was determined that human peripheral vessel myofibroblasts and human bone marrow mesenchymal stromal cells grown on nitinol bases coated with titanium or tantalum-enriched surface layers exhibit a nearly two times higher mitotic index. Response to implantation of pure nitinol, as well as nano-structure nitinol with titanium or tantalum-enriched surface layers, was expressed though formation of a mature uniform fibrous capsule peripherally to the fragment. The thickness of this capsule in the group of animals subjected to implantation of pure nitinol was 1.5 and 3.0-fold greater than that of the capsule in the groups implanted with nitinol fragments with titanium- or tantalum-enriched layers. No signs of calcinosis in the tissues surrounding implants with coatings were observed. The nature and structure of the formed capsules testify bioinertia of the implanted samples. It was shown that the morphology and composition of the surface of metal samples does not alter following biological tests. The obtained results indicate that nano-structure nitinol with titanium or tantalum enriched surface layers is a biocompatible material potentially suitable for medical applications.