INTERACTION OF ARTIFICIAL CARBON PYROCERAM MITRAL VALVE WITH BLOOD PLASMA

摘要

The nanocrystalline material of an artificial carbon pyroceram mitral valve obtained by sintering of 15 wt. percent B_4C with crystals <10 nm that are uniformly distributed in 85 wt. percent carbon with particles approx10 nm has exceptionally high chemical stability in blood plasma. The electrochemical interaction resulting from contact with a possible microadditive (for example, iron) on the valve surface is experimentally modeled by polarization induced by an external current source specially to create extreme corrosion conditions. The interaction kinetics is studied at 37 deg C using anodic polarization curves. Curcumin is used as an analytical reagent for spectrophotometry of boron traces in a solution. Emissive spectroscopy is used to determine iron traces in the spume-like film formed after polarization. It is established that a chemisorbed oxygen film forms when microgalvanic elements appear at 0.4 V and stable passivation of the valve surface is observed at approx 1.0 V since a low-conductive nanostructured carbon film forms. It is shown that this film results from the discharge of alpha-amino acids on the valve surface (amino acid residues of complex peptide chains of plasma proteins) containing heterocyclic rings. The sessile drop method shows that the valve is promptly wetted by blood plasma (wetting angle is 50 deg), this also promotes the formation of a stable protective film on its surface.