For my master's thesis, I grow cells on nano/micro-structured surfaces. I have some questions regarding the hydrophilic/hydrophobic nature of cell growth substrates.
I have read that some surfaces, such as pillars, have hydrophobic properties (as shown by water contact angle measurements).
What is the idea behind measuring the water contact angle of surfaces of which topography is changed (but not chemistry)?
For the cells, is the hydrophobicity of the substrate coming from topography change, the same as the hydrophobicity coming from chemical modifications (as for example, coating with hydrophobic molecules)?
For example, is the protein adsorption affected differently?
surface roughness (as a consequence of grafting from a substrate surface for example) affects the surface properties of a material such as hydrophobicity. In this case, surface roughness will be affected by the molecular weight of the grafted polymer. from my personal experience, surface chemistry has a higher impact.
Dear Sara,
the contact angle between a liquid and a solid is due to an effect named 'surface tension'. Surface tension effects that the surface area of liquids is minimized (water droplets form spheres) due to intramolecular attractive forces (cohesion, van der Waals interaction).
Outside of the surface the attraction is zero. At interfaces the attraction between molecules of solid and liquid (adhesion) must additionally be considered. This forces can be higher or lower than between pure liquid molecules. Therefrom arise different contact angles at the edge between solid and liquid.The different attractive forces effect either a wetting (dish liquid, hydrophil and small contact angle) or repelling (hydrophob- big contact angle).
Youngs equation can be used to calculate the contact angle. The structure of the surface influences the interaction and therefore the contact angle. But this is not subject of my knowledge.
With Regard
R. Mitdank
Sara Mingu-Akmete Surface hydrophobicity/hydrophilicity is primarily depended on the chemistry of the material. Therefore each surface (unique material) has an intrinsic hydrophobic/hydrophilic property. However, depending on the size and pattern of the imprinted topography (typically in nanoscale), the surface can go more hydrophobic or hydrophilic in the sense of interaction with water droplet and wettability angle. If the surface is too hydrophobic is less likely for the protein such as fibronectin or collagen to attach to the surface and hence the cells.
Hydrophilicity is evaluated basically by water contact angle which is influenced in trun by surface topography. Topography is a broad term which describes the surace nano-micro texture, porosity, pore size, pore geometry, and pore distribution pattern. These physical factors as well as chemical factors (i.e. surface chemitry, surface energy, surface charge, and etc) can modify the hydrophilicity. Please analyse your substrate considering all related factors as described. Best
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