Novel nanodiamond coatings for durable xenogenic heart valve prostheses: Mechanical properties and in vivo stability

Nanodiamond adsorption coatings were obtained on the surface of the collagen tissue crosslinked by glutaraldehyde for enhancing its mechanical properties, including stress at break, elongation at break, and elastic modulus (Young's modulus). The effect of nanodiamonds of positive and negative surface charge was compared. Negatively charged nanodiamonds strongly influenced the mechanical characteristics compared with positively charged particles on the background of its smaller surface concentration that was determined using tritium-labeled nanodiamonds. A chitosan layer was applied from the solution of supercritical CO2 to prevent calcification of the tissue. In vivo experiments showed that the nanodiamond layer is stable and does not lead to additional calcification of the tissue. However, we observed higher metal concentrations on the tissue covered with negatively charged nanodiamonds. Note that the total calcification of bovine pericardium was less than for non-covered tissue. Our data revealed that layer-by-layer applied nanodiamond and chitosan films significantly enhance the mechanical properties of the bovine pericardium and allowed us to hope for the creation of a wear-resistant material based on it.