Influences of Grain boundaries and Surface Nanocrystallization on stainless steel on Psedomonas aeruginosa Biofilm's adherence

A common complication associated with medical implants is the infectious bio-film, which can cause chronic infection that is difficult to control. Grain boundaries (GBs) in materials of medical implants are often preferential locations for bacteria to congregate, which could be attributed to higher affinity of grain boundaries for bacterial bio-films. In this study, the molecular interaction of the Pseudomonas aeruginosa receptor binding domain, a self-folding domain of 17 amino acid residues derived for the PilA structural protein, which can represents properties of Pseudomonas aerginosa biofilm, with microcrystalline stainless steel surfaces was examined with atomic force microscopy (AFM) both at grain boundaries and within grains. Adherence of Pseudomonas aeruginosa biofilm to nanocrystallized stainless steel surface was also determined using AFM. Results indicate that adherence of biofilm' adherence at grain boundaries of microcrystalline surface is 2-fold higher than that of inside grains. Nanocrytalline surface is more resistant to biofilm than the microcrystalline one due to the formation of a strong oxidation film after annealing and thermal oxidation process. Surface nanocrystallization for enhanced corrosion resistance of Ag-incorporated 304 stainless steel surface was also studied. It is demontstrated that nanocrystallization of the antibacterial agent-incorporated stainless steel surface also provides an effective approach to control the corrosion problem resulting from the typical galvanic effect of multiphase alloys.