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Journal Club for October 2016: Roughness evolution of biomaterial surfaces

Henry Tan's picture

As an example, here we discuss implant-associated infection from the mechanics point of view on bacteria adhesion affected by the biomaterial surface roughness:

1.    Implant-associated infection, a leading cause of failure in many biomedical devices, is caused by adhesion of bacteria to the surface of biomaterials. Implant-associated infection is difficult to treat, for example, joint replacement infections may occur deep around the artificial implants.

2.    Microbial adhesion and subsequent biofilm formation are mediated by van der Waals attractive forces, electrostatic repulsive forces, and surface hydrophobicity. The predominance of these forces is dependent on the distance between the microorganism and the surface, usually at distances greater than 50 nm van der Waals forces are the main factor, while at closer distances (10−20 nm) a combination of both van der Waals forces and electrostatic interactions controls cell adhesion.

3.    Implant surface roughness is an important property relevant for the bacterial adhesion process, with the irregularities of the surfaces normally promoting bacterial adhesion and colonization.

4.    For metals used in medical implants, the desired surface roughness is usually below 10 nm. At nanometre scale rough surface promotes friction, hence reduces the mobility of the bacteria; this sessile environment expedites the biofilm growth.

5.    To reduce the roughness, surface nanotopography of medical implants is an important approach that can control the extent of bacterial adhesion.

6.    Surrounding the implant are soft and hard tissues, as well as the corrosive body liquid. Whether the roughness of an initially nanoscale smooth surface will grow or decay is of crucial importance for implant devices.

7.    For a stress metal implant under shallow chemical etching, the roughness with spatial frequency below a critical value grows while the roughness of higher frequency decays.

8.    A rougher surface had lower constraint for electrons to escape from peaks, resulting in lower chemical potential.

References:

Tan, H. (2016) In vivo surface roughness evolution of a stressed metallic implant. Journal of the Mechanics and Physics of Solids, 95, 430–440.

Truong, V.K., Pham, V.T.H., Medvedev, A., Lapovok, R., Estrin, Y., Lowe, T.C., Baulin, V., Boshkovikj, V., Fluke, C.J., Crawford, R.J., Ivanova, E.P. (2015) Self-organised nanoarchitecture of titanium surfaces influences the attachment of Staphylococcus aureus and Pseudomonas aeruginosa bacteria. Appl. Microbiol. Biotechnol. 99, 6831-6840.

Ryu, J.J., Shrotriya, P. (2015) Mechanical load assisted dissolution response of biomedical cobalt-chromium and titanium metallic alloys: Influence of in-plane stress and chemical environment. Wear 332-333, 662-668.

Desrousseaux, C., Cueff, R., Aumeran, C., Garrait, G., Mailhot-Jensen, B., Traoré, O., Sautou, V. (2015) Fabrication of acrylonitrile-butadiene-styrene nanostructures with anodic alumina oxide templates, characterization and biofilm development test for Staphylococcus epidermidis. PLoS ONE 10, Article number e0135632.

Yoda, I., Koseki, H., Tomita, M., Shida, T., Horiuchi, H., Sakoda, H., Osaki, M. (2014) Effect of surface roughness of biomaterials on Staphylococcus epidermidis adhesion. BMC Microbiology 14, 234-240.

Wang, J., Yao, J., Gao, H. (2012) Specific adhesion of a soft elastic body on a wavy surface. Theoretical and Applied Mechanics Letters, Article 014002.

Comments

Henry Tan's picture

News from MaterialsToday:

A simple process that roughens the surface and alters the grain size of metallic biomedical implants could deter the bacteria that cause infections and complications after surgery, according to researchers from Politecnico di Milano, Massachusetts Institute of Technology, Northeastern University, University of Cambridge, and King Abdulaziz University.

Sara Bagherifard, Daniel J. Hickey, Alba C. de Luca, Vera N. Malheiro, Athina E. Markaki, Mario Guagliano, Thomas J. Webster (2015) The influence of nanostructured features on bacterial adhesion and bone cell functions on severely shot peened 316L stainless steel. Biomaterials 73, 185–197.

SaraBagheri's picture

Thanks for highlighting our paper. This is a purely mechanical treatment that induces hierachical surface roughness without compromising the biocompatiblity of the treated material. This surface roughness turns out to particularly reduce the adhesion of gram positive bacteria to the surface. 

the treatment itself enhances also the mechanical properties of the treated metallic material, thus I would say it is efficient in improving different aspects of the materials' functionality. 

Henry Tan's picture

Thank you Sara, this is a very interesting piece of experimental work. Could you explain why surface roughness effect to the adhesion is not that strong for gram-negative bacteria? Maybe mechanicians here can do some modelling for this?

Regards, Henry.

SaraBagheri's picture

Interesting subject indeed. We postulated that different responses from gram negative bacteria could be due to the extra outer membrane surrounding their peptidoglycan layer that could cause a cushioning effect in the interaction with the nanofeatures of the substrate material. It would be great to model this interaction and if you are interested in the subject, we would be happy to provide you with any additional data you might need.

Best, Sara

Henry Tan's picture

Yes, we are interested in this cushioning effect of the interactions between the nano-features of bacteria and implant materials. Understanding the adhesion mechanisms of gram-positive and gram-negative bacteria is important for the medical treatment of different type of implant-associated infections.

Bin Liu's picture

Henry

 

Thanks for sharing this interesting topic. Regarding the description of roughness, are the spatial frequency and amplitude enough to characterize the interaction? I think isotropic and anisotropic roughness patterns will play a different role.

 

Bin

SaraBagheri's picture

I totally agree that the conventional surfce roughness parameters do not seem to be enough to describe the morphology of the surfaces anymore. This is actually a problem that is resulting in numerous contradicting data on interaction of cell/bacteria with rough substrates in the literature. I believe new approaches have to be developed to characterize the spatial distribution of nano and micro features.

Henry Tan's picture

Bin, you bring in a challenging topic. Previously we demonstrated that, both theoretically and experimentally, when immersed in a corrosive liquid and subjected to a non equi-biaxial in-plane stress loading, a metal surface with an initial isotropic roughness will automatically develop anisotropicity.

K.-S. Kim, J. A. Hurtado, and H. Tan (1999) Evolution of a Surface-Roughness Spectrum Caused by Stress in Nanometer-Scale Chemical Etching, Phys. Rev. Lett. 83, 3872 – 3875.

Many material surface properties, such as surface mobility and wettability, depend on the roughness tensor. We have to clarify, both experimentally and theoretically, this dependence in order to fix numerous contradicting data in literature as mentioned by Sara.

Henry Tan's picture

This paper is interesting about anisotropic cell behaviours:

Crouch AS, Miller D, Luebke KJ, Hu W. (2009) Correlation of anisotropic cell behaviors with topographic aspect ratio. Biomaterials 30, 1560-7

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