Tissue engineering involves applying the principles of engineering and life sciences toward the development of biological replacements that restore, maintain, or improve t issue function. Investigators have attempted to eng ineer many mammalian t issues using a v ariety of approaches. Broadly, these can be classi ed as in vitro approaches and in vivo approaches. In the former approaches, cells are cultured on a sca old in vitro, where they form functional tissue for future transplantation. In the latter approaches, sca olds are designed such that a er i mplantation t hey re cruit nat ive t issue c ells t hat a re g uided to create new t issue or enhance wound healing. In both approaches, it has been demonstrated that cells respond to a v ast a rray o f c ues p rovided b y s ca olds a nd c ulture c onditions, i ncluding c hemical, biochemical, electrical, mechanical, and topographical stimuli. us, in order to achieve predictable cell responses, materials for tissue engineering are o en engineered to mimic the structure and properties of natural tissue, both at their surfaces and in the bulk. Surface properties that dictate the interactions between t he m aterial a nd i ts en vironment, w here t he en vironment c onsists o f c ells a nd i mportant biomolecules, are by nature nanoscale properties. Bulk properties are also dependent on the nanoscale organization of materials. is is because natural tissues are designed and assembled in controlled ways, at a hierarchy of length scales ranging from the macroscale to the nanoscale.