|Title||Morphological factors involved in adhesion of acid-cleaned diatom silica|
|Publication Type||Journal Article|
|Year of Publication||2014|
|Authors||Kopanska K.S, Tesson B, Lin H.S, Meredith J.C, Hildebrand M, Davis A.|
|Type of Article||Article|
|Keywords||Adhesion; cell-wall; detachment; diatoms; enteromorpha; morphology; motility; nanotechnology; particle adhesion; self-assembled monolayers; silica; strength; surfaces; wettability|
Purpose Diatoms, unicellular microalgae with silica cell walls, have strong adhesive properties, which are dominated by chemical interactions between secreted organic material and the substrate. Possible technological applications of diatoms are likely to involve the adhesion of silica particles, or derivatives, which have been cleaned of organic material. Because the morphologies of diatom cell walls are far more complex than defined model structures, the relationship between morphology and adhesion for such materials is unknown. Methods In this paper we develop a new approach to monitor the adhesion of acid-cleaned diatom silica using parallelplate flow chambers. We have evaluated factors such as settling time, extent of dryness, and substrate properties, and compared diatom species with silica features differing in size, shape, and percentage of surface contact area. Results Results indicated better adhesion of particles with higher surface contact area below a threshold of overall size, and a contribution by the number of possible contact surfaces to initial adhesion. We identified two stages in adhesion response to increasing shear stress. In the first stage, at low shear stress, species-dependent morphology played a major role in determining the strength of adhesion. After loosely adhered particles were removed at low shear, a second stage of persistent adhesion emerged at higher shear stresses. In the second stage, variations in morphology had a much smaller effect on adhesion. Conclusions These results identify conditions and fundamental morphological features for adhesion that can be utilized in future technological applications of silica particles with complex shapes.