is an interesting leap from the studying of contact phenomenon towards a more clinical

application.

 The field of contact guidance using topographical cues is quickly becoming more

noticeable in clinical fields. Several excellent reviews have been authored and are a good

starting point for an overview on the topic.[1 3 51] However, topographical features are

not the only tools for directing cell growth, as the chemistry of the substrates is becoming

more popular in terms of directed cell growth and adhesion. As more studies are

performed and a better understanding of the issues involved is achieved, clinicians and

researchers are discovering the importance of the texture of medical implants as well as

the chemical moieties on the surfaces.

Surface Chemistry

 Surface chemistry plays a large role in the field of contact guidance for

controlling the results of cell proliferation. Carter originally demonstrated that cells

exhibit a preference to hydrophilic areas of patterned cellulose acetate and palladium

metal surfaces.152' 53] The cells migrated towards the metal and, in a separate study, along

a gradient of metal concentration densities towards the more dense and thereby more

hydrophilic areas. These studies were later duplicated and confirmed by Harris.[54]

Currently, surface treatments are typically deposited in regular patterns using the same

photolithographic techniques as with the topographical substrates. Self-assembled

monolayers[551 (SAMs) and areas of enhanced adsorption of proteins due to surface

energy seem to be the most popular. A study by Britland, et al. deposited a pattern of

alternating hydrophobic dimethyltrichlorosilane groups with aminosilane groups on glass

slides. No residual topography resulted and BHK cells showed a definite preference for

the aminosilane sections, as the cells were crowded and aligned along the border rather