Multi-scale surface topography to minimize adherence and viability of nosocomial drug-resistant bacteria

Highlights: • Induction of multi-scale surface architecture is achieved through wet etching on aluminum substrates. • The multi-scale surface architecture on Al and its alloys kills as well as repels bacterial cells. • Multi-drug resistant bacterial strains isolated from the hospitals are also lysed by the etched Al surfaces • Combination of ranges of surface roughness parameters are identified for designing surfaces with high bactericidal activity. Toward minimizing bacterial colonization of surfaces, we present a one-step etching technique that renders aluminum alloys with micro- and nano-scale roughness. Such a multi-scale surface topography exhibited enhanced antibacterial effect against a wide range of pathogens. Multi-scale topography of commercially grade pure aluminum killed 97% of Escherichia coli and 28% of Staphylococcus aureus cells in comparison to 7% and 3%, respectively, on the smooth surfaces. Multi-scale topography on Al 5052 surface was shown to kill 94% of adhered E. coli cells. The microscale features on the etched Al 1200 alloy were not found to be significantly bactericidal, but shown to decrease the adherence of S. aureus cells by one-third. The fabrication method is easily scalable for industrial applications. Analysis of roughness parameters determined by atomic force microscopy revealed a set of significant parameters that can yield a highly bactericidal surface; thereby providing the design to make any surface bactericidal irrespective of the method of fabrication. The multi-scale roughness of Al 5052 alloy was also highly bactericidal to nosocomial isolates of E. coli, K. pneumoniae and P. aeruginosa. We envisage the potential application of engineered surfaces with multi-scale topography to minimize the spread of nosocomial infections.