CHAPTER 1
 INTRODUCTION

 The ability to predict and control a biological response to a biomedical device

would be a skill of dramatic technological and economic importance. Since man first

attempted to replace nature's mechanisms and structures with artificial substitutes, he has

met mainly with frustration marked with varying degrees of success. For implant

materials, the factors that determine success are many, but the interaction between the

surface and the surrounding tissue is one of the most important. The characteristics of

that surface shape that interaction, and their secrets are slowly becoming known.

 Contact guidance is a term used to describe a material's ability to direct the

alignment and growth patterns of biological cells or tissue. It has long been understood

that the surface a cell grows on impacts its size, shape, and metabolism. By determining

the aspects of the material and the surface that influence contact guidance, there is a

better opportunity to design a hierarchical system to elicit the desired response. Contact

guidance can be controlled by topography and surface chemistry. Typically, when cells

are exposed to mechanical features such as ridges and grooves, the cells align and travel

along the length. The addition of roughness at certain levels can improve a biomaterial's

ability to promote cell adhesion, while disrupting adhesion at different levels.[1-3]

 Patterning surface chemistry on samples to change the wettability and surface

energy has been very successful in controlling cell growth. Alternating strips or islands

of adhesive proteins and materials with different surface energies have been examined.

The incorporation of texture with surface chemistry allows for mutual interactions to