Wettability gradient

Lee JH, Khang G, Lee JW, Lee HB (1998) Interaction of different types of cells on polymer surfaces with wettability gradient. J Colloid Interface Sci 205 323-330... 

Zhao H, Beysens D (1995) From droplet growth to film growth on a heterogeneous surface -condensation associated with a wettability gradient. Langmuir 11 627-634... 

Pitt, W. G. Fabrication of a continous wettability gradient by radio frequency plasma discharge,. /. Colloid Interface Sci. 1989, 133, 223-237... 

Elwing, H. Welin, S. Askendal A. Nilsson U. Lundstrom, I., A wettability gradient method for studies of macromolecular interactions at the liquid/solid interface,. /. Colloid Interface Sci. 1987, 119, 203-210... 

Welin-Klintstrom, S. Askendal, A. Elwing, H., Surfactant and protein interactions on wettability gradient surfaces, J. Colloid Interface Sci. 1993, 158, 188-194... 

The paper describes some of our studies of protein adsorption on solid surfaces. An emphasis is made on newly developed experimental techniques and on recent biological model experiments. We therefore discuss the use of a wettability gradient along a solid surface to Investigate, In a convenient way, the Influence of surface energy on the adsorption of protein molecules. The behavior of the complement system at solid surfaces Is also discussed, with special attention to surface Induced conformational changes of human complement factor 3. 

The protein adsorption studies described were all at the liquid - solid or solid - air interface. Lateral scanning elllpsometry was made to evaluate the surfaces with a wettability gradient. Experiments were most often made on (modified) silicon surfaces. The experimental results are also discussed in relation to the proposed theoretical models for protein adsorption. 

Neuhaus S, Padeste C, Spencer ND. Versatile wettability gradients prepared by chemical modification of polymer brushes on polymer foils. Langmuir 2011 27(11) 6855—61. 

TABLE 40.8 Proliferation Rates of Fibroblast Cells on Wettability Gradient PE Surfaces... 

Lee, J.H., Lee, S.J., Khang, G., and Lee, H.B. 1998c. Interactions of cells onto microporous polycarbonate membrane with wettability gradient surfaces, /. Biomat. Sci., Polm. Edn. (in press). 

Figure 7. Top Drops of water deposited on coated glass slides that were gradually immersed in a 2 M solution of NaOH at 15 om/s (A) and 5 pm/s (B) using a linear motion drive. Bottom Electron microscopy images taken along the wettability gradient on the surfaces. Immersion times in the NaOH solutions and corresponding contact angles are indicated.

The experiment indicates that, in principle, this technique could be used to create a full length wettability gradient from superhydrophobic to superhydrophilic on a single substrate which, to our knowledge, has been rarely achieved so far [38-40],... 

The enhanced recovery of residual oil, which occurs as a consequence of wettability gradients in a reactive alkaline-acidic system, is illustrated in Figure 10. Incremental production in this tertiary flood begins about 0.6 PV after caustic injection and ends after injection of approximately 1.0 PV of caustic. This production is preceded by a pressure peak with a maximum which is two times the steady-state pressure drop of the secondary water-flood. The pressure drop maximum coincides with the concentration minimum of the hydroxyl ion species which elutes at the rear of the tertiary oil bank. 

Depending on the type of cells and the presence of proteins in the solution, the adhesion of cells to wettability gradients has been observed to vary. Whereas endothelial cells adsorb, proliferate and grow more pronouncedly on the hydrophobic end of wettability gradients, algal spores behave differently and adhere more strongly to the hydrophilic end." On the other hand,... 

Kennedy et al. found similar osteoblast adhesion along the entire wettability gradient, although more pronounced proliferation was observed at the hydrophobic end. Finally, Lee et al. reported increased pheochromocytoma cell (PC-12) adhesion to an intermediate surface wettability, whereas neurite growth was enhanced at the hydrophilic end. The results of all these studies, however, are influenced by the presence of proteins and other components in the cell media, which may pre-adsorb onto the wettability gradient and mediate cell adhesion, especially in those cases where enhanced cell adhesion corresponds to an enhanced protein adsorption. ... 

We shall now examine more quantitatively the motion of drops and puddles on horizontal surfaces bearing the imprint of a wettability gradient in the. r-direction. Both 7so( ) and depend on the position. x, and... 

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