The influence of metallic surface topography towards adhesion of gram-positive & gram-negative bacteria

The presence of bacteria on metals is considered a serious source of potential contamination for domestic and industrial environments. Possible contributing factors to the formation of biofilm are related to the surface properties of materials used such as surface topography and hydrophobicity. Surface topography and hydrophobicity will be the focus in this investigation towards Gram-positive and Gram-negative bacteria (S. aureus, E. coli and B. subtilis) adhesion. Modified surfaces of 316L stainless-steel and Ti6Al4V, titanium prepared by polishing, WEDM and laser-assisted technique and the as-received substrates were also considered in the study. The corresponding surface topography and contact angle measurement were assessed by Bruker Optical Profilometry and Kruss DSA, Germany. The number of adhered bacterial on metal surfaces was determined by O.D, CFU and Fluorescent Microscopy. Polished, WEDM and laser-assisted surfaces managed to mitigate bacteria adhesion as opposed to controlling surfaces but increased the adhesion of E. coli on both stainless steel and titanium. The introduction of laser-assisted technique using argon gas successfully combatted the adhesion of both Gram-positive and Gram-negative bacteria, revealing the lowest adhesion for S. aureus and E. coli, surpassing those on polished surface and WEDM. The success factor was presumably contributed by the ability to suppress oxidation, while contours and nanograin surface effects prevent entrapments of bacteria whilst inducing an antibacterial property through contact killing mode