Dear Sahand,

Actually, I think more surface parameters could have some influences beside surface roughness like kurtosis factor, slope of asperities, Skewness, heights of asperities and etc. I found out some experimental relation between surface parameters and wear rate of applied layers (Article Correction of Archard Equation for Wear Behavior of Modified...

Dear Sahand Behrangi ,

It is well known that nanocorrugated surfaces can reduce bacterial adhesion and even prevent the formation of bacterial biofilm. Please have a look at these two articles and references therein:

Article Nanocolumnar coatings with selective behavior towards osteob...

Article Antibacterial Nanostructured Ti Coatings by Magnetron Sputte...

a potential synergy between bacterial growth and surface roughness could be observed if the peak-to-peak distance of the surface is comparable with the size of bacteria or cellule that need to locate and grow in the surface. I recommend to check accurately the topography with 3D profilometry or AFM and benchmark with typical size of bacteria you are interested in. This effect is used beneficially to tailor the surface roughness of metal prosthesis in order to fasten the growth of osteo cellulae. BR

Arvin Taghizadeh Tabrizi

Dear Arvin, thanks a lot for the answer and the mentioned article.

Dear Simone Vezzù

Thanks for your answer. Actually, I have not checked the topography of the films by AFM yet but I suppose the size of the bacterium will be much bigger than peak-to-peak distance. For example S. aureus has the size of approximately 500-1000 nm. But for my samples, the roughness values which I measured by confocal microscope are as in the attachment. Do you think the peak-to-peak distance could be estimated to be much less than the bacterium size?

Dear Jose-Miguel Garcia-Martin

Thank you very much for the answer. I will read through the articles you mentioned.

The bactericidal efficiency is the properties not for the particles, but for ions which created on the surface of particles. It means, that microorganisms adsobed on the particle/s surface leads to partial dissolution of this surface - for nanoscale particles the amount of ions already presented on the surface is high, but the effect cannot be the same for all types of bacteria/yeasts etc. due to various membranes types, methabolism etc. So, your results can be explained for some systems not only via nanoparticles size and concentration of metal ions on the surface, but also via bacteria metabolism or adsorption mechanism or cell membraine specific structure.

Ekaterina Zolotukhina

Thanks for the answer. Yes, I agree. But the question is whether the roughness of the surface can influence the viability of the microorganisms (and bacteria in this case). I do not use nanoparticles but a thin film in which Cu atoms are mostly incorporated in the ZrN lattice.

Actually, I am not a biologist but I read some literature that mentioned briefly this effect. I believe that the morphology of the surface and the bacterium can be of great importance. Once I did just some preliminary tests and produced some samples with significantly different roughnesses. I assessed their efficiency against E. coli and we saw a huge difference. I am doing a systematic study on this. Probably we will use just E. coli. As you said, different bacteria can behave differently...