Antibacterial Properties Of Ag/Cu Implanted Stainless Steel

Stainless steel implanted by silver and copper ions simultaneously was firstly reported in this work with a metal vapour vacuum arc source. The implanted layer was characterized by X-ray photoelectron spectroscopy. The antibacterial rates were estimated by standard plate count method. The results indicated that the antibacterial SS with a total dose of 2×1017ions/cm2 of Ag/Cu ions has good antibacterial activities (sterilizing rate≥95%) against Escherichia coli and Staphylococcus aureus but poor antibacterial activities against Aspergillus niger. After annealing treatment, the antibacterial SS showed excellent antibacterial activities against Escherichia coli, Staphylococcus aureus and Aspergillus niger. The sterilizing rate against Aspergillus niger was over 98% when implantation dose of copper ions was above 1.5×1017ions/cm2. X-ray core level spectra indicated that the implanted silver and copper ions exist in metallic state in the implanted layer. The depth profile showed that the maximum concentration depth of both silver and copper ions were about 46.5 nm below the surface. Electrochemical polarization curves indicated that the corrosion resistance of stainless steel was slightly enhanced after implantation of silver and copper ions.A preliminary study was made on antibacterial mechanisms of silver implanted AISI420 stainless steel. The implantation dose of silver ions was 2×1017 ions/cm2. Antibacterial rate of silver implanted stainless steel was 96% against Escherichia coli estimated by standard plate count method. Released silver ions were found in solution by inductively coupled plasma atomic emission spectroscopy. The silver ions concentration was 130 ppb after incubation. The pericellular membrane of Escherichia coli became blurred after 3 h incubation and almost disappeared after 5 h incubation. Antibacterial rate of silver implanted SS against Escherichia coli was reduced to 58% from 96% when the bacteria solution mixed with 3×10-4 mol/L EDTA, indicating that the released silver ions play an important role in the antibacterial process. The silver ions implanted SS remained good antibacterial activities (sterilizing rate≥95%) after exposed in atmosphere or immersed in tap water for 160 days.