Microfluidic detachment assay to probe the adhesion strength of diatoms

Abstract

Fouling release (FR) coatings are increasingly applied as an environmentally benign alternative for controlling marine biofouling. As the technology relies on removing fouling by water currents created by the motion of ships, weakening of adhesion of adherent organisms is the key design goal for improved coatings. In this paper, a microfluidic shear force assay is used to quantify how easily diatoms can be removed from surfaces. The experimental setup and the optimization of the experimental parameters to study the adhesion of the diatom Navicula perminuta are described. As examples of how varying the physico-chemical surface properties affects the ability of diatoms to bind to surfaces, a range of hydrophilic and hydrophobic self-assembled monolayers was compared. While the number of cells that attached (adhered) was barely affected by the coatings, the critical shear stress required for their removal from the surface varied significantly.

Keywords:

• diatom
• shear force
• self-assembled monolayers
• microfluidic assay
• adhesion
• fouling release
• laboratory assay

Acknowledgements

The authors gratefully acknowledge the supply of cultures, and the kind help and advice of J. Finlay, G. Cone, M.E. Pettitt, and M.E. Callow (University of Birmingham). They thank M. Grunze (IFG, KIT) for the stimulating discussions and suggestions. They also acknowledge the preparation of the gold slides by G. Albert (IFG, KIT).

Conflict of interest disclosure statement

No potential conflict of interest was reported by the authors.

Supplemental material

The supplemental material for this paper is available online at http://dx.doi.org/10.1080/08927014.2015.1061655.

Additional information

Funding

The work was funded by the Office of Naval Research [grant number N00014-12-1-0498], [grant number N00014-15-1-2324] and the Helmholtz program Biointerfaces (KIT).