Study On The Mechanism Of The Release Of Cu Ions And The Biological Effect Of Cu-bearing Stainless Steel

Biomedical stainless steel becomes the most widely used biomedical metallicmaterial because it has favorable corrosion resistance high strength, toughness andlow cost. However, the current medical stainless steel does not have bioactivity. Themain cause of the failure of surgical implanting operation is bacterial infections. Aspeople with quality of life more and more high requirements, biomedical metallicmaterials need to have excellent antimicrobial. Cu element not only is one of humanessential trace elements, but also has admirable antimicrobial, so appropriate amountsof Cu were added into the currently used medical stainless steels in order to develop anovel class of Cu-bearing stainless steels, which can continuously release Cu ionsafter heat treatment and then offer the stainless steels the anti-infection andbiomedical functions. In this study, mechanism of Cu ion releasing and theirbiological functions of Cu-bearing stainless steels were studied. The main researchresults are summarized as following:(1) Mechanism of Cu ion releasing of Cu-bearing stainless steelsPassive film in the surface of Cu-bearing stainless steel was different fromcommon medical stainless steels. Passive film of Cu-bearing stainless steel containedCu. Cu-bearing stainless steels released Cu ions when the passive film corroded. Thecorrosion resistance of the Cu-bearing steel was not obviously deteriorated comparedwith the common medical stainless steel, with a little bit reduction of pittingresistance because of rich copper phase precipitation.(2) Antibacterial properties of Cu-bearing stainless steelsCu-bearing stainless steels had strong antibacterial effect against E. coil andS.aureus which can cause the failure of surgical implanting operations. Cu-bearingstainless steels also had strong inhibitory effects against bacterial biofilm. Butantibacterial effect declined when Cu-bearing stainless steels were passivated by nitricacid. The minimum bactericidal concentration (MBC) of Cu ions were50ppb.(3)Biological properties of Cu-bearing stainless steelsThe hemolysis ratios of Cu-bearing stainless steels were all less than5%,indicating that an appropriate addition of copper did not affect the hemolysis behaviorof the steel. Biological safety evaluation shows that Cu-bearing stainless steels had nocytotoxicity. Cu-bearing stainless steels accord with implanted standard.