Microfluidic shear force assay to quantify bacterial adhesion strength to test foul-release coatings for marine applications

M.P. Arpa Sancet^1,2, S. Bauer^1,2, C. Christophis¹_, A. Rosenhahn^1,2

¹ Applied Physical Chemistry, Ruprecht-Karls-University Heidelberg, Im Neuenheimer Feld 253, 69120 Heidelberg, Germany

² Institute for Functional Interfaces, IFG, Karlsruhe Institute of Technology,

PO Box 3640, 76021 Karlsruhe, Germany

e-mail: Arpa@uni-heidelberg.de

For both, marine biofouling and biomedical applications, the quantification of bacterial adhesion is of major importance to understand and support the development of new materials. A microfluidic assay has been developed that allows to determine the adhesion strength of bacteria on surfaces [1]. Specifically for marine applications, the formation of bacterial biofilm is an important step in colonization of submerged surfaces [2], and the development of ways to attenuate microbial attachment or to achieve their easy removal is desirable. The marine bacterium Cobetia marina is inoculated in this microfluidic device on the surfaces of interest. The bacterial detachment is caused by a hydrodynamic shear flow [3] which is continuously increased and the removal is recorded via video microscopy. The adhesion strength is determined as the shear stress needed to detach 50% of the adherent bacteria. The assay parameters were varied in order to find the optimal conditions to carry out the biological assays. Besides the experimental setup and the optimization of the assay, the adhesion strength on a series of surfaces with different ability to bind water was measured.

[1] Arpa-Sancet, M., C. Christophis, et al., "Microfluidic assay to quantify the adhesion of marine bacteria", Biointerphases, 2012, 7, 1-9.

[2] Yebra, D.M., S. Kiil, and K. Dam-Johansen, “Antifouling technology - past, present and future steps towards efficient and environmentally friendly antifouling coatings”, Progress in Organic Coatings, 2004, 50, 75-104.

[3] Bacabac, R.G., et al.,”Dynamic shear stress in parallel-plate flow chambers”, Journal of Biomechanics, 2005, 38, 159-167.