Bacterial response to spatially organized surface patterns.

The growing microorganisms within the biofilm show different characteristics than those that develop in the planktonic state. One of the most important is their greater tolerance (or resistance) antimicrobial (including disinfectants) that can range from 100 to 1000 times longer than in planktonic microorganisms. Specifically, Staphylococcus epidermidis is one of the most important etiological agents of infections associated with biomedical materials due to its ability to adhere and form biofilms on the surface of permanent medical devices. Due to the high resistance to existing antibiotics, other options need to be assessed.

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The influence of nanometer scale roughness on bacterial adhesion and subsequent biofilm formation has been evaluated using spatially organized microtopographic surface patterns for opportunistic pathogens of the genus Staphylococcus, responsible for associated-biofilm infections on biomedical devices.  

The results presented demonstrated that regardless of the strain employed the initial adhesion events to these surfaces are directed by cell-surface contact points/areas maximisation and thus, bacterial cells actively choose their position initial to settle on spatially organized surface patterns that contain features with nanometer scale vertical dimensions (i.e. significantly smaller than the size of the cells). Accordingly, bacterial cells were found to preferably adhere to the square corners and convex walls of recessed surface features rather than the flat or concave walls of equal protruding features. It was further shown that all surfaces patterns investigated produce a significant reduction in bacterial adhesion (40 - 95 %) and biofilm formation (22 - 58 %). This important observation could not be related to physical constrains or increased solid surface hydrophobicity. It is evident that other causes, such as nanoscale surface roughness-induced interaction energies, might be controlling the process of bacterial adhesion and biofilm formation on surfaces with well-defined nanoscale topography.

This is a first step to demonstrate that that engineered topographies with nanometer scale roughness are as effective at inhibiting bacterial adhesion and colonization as those with microscale surface roughness. Further studies are still needed to draw more definitive conclusions, but collectively, the results presented in this study contribute to our understanding of a largely unexplored experimental field, i.e. how bacterial cells respond to engineered topographies with nanoscale surface roughness, that could help develop new materials to effectively control bacterial adhesion and biofilm formation, in the absence of antimicrobial agents responsible for resistances, for a wide range of biomedical and industrial applications.


The paper can be found here:





María Coronada Fernández Calderón

Researcher and Associate Professor, Biomedical Research Networking Center in Bioengineering, Biomaterials and Nanomedicine (CIBER - BBN) and University of Extremadura

My research activity is included in the area of Biomaterials and Tissue Engineering, mainly focused on biofilm-based healthcare associated infections and the strategies to detect and prevent the development of microbial biofilms in biomaterials for medical devices.