This field of emphasis covers novel therapeutic development across all biological length scales from molecules to cells to tissues. At the molecular and cellular levels, this area of research encompasses the engineering of biomaterials, ligands, enzymes, protein-protein interactions, intracellular trafficking, biological signal transduction, genetic regulation, cellular metabolism, drug delivery vehicles, and cell-cell interactions, as well as the development of chemical/biological tools to achieve this. At the tissue level, this field encompasses two sub-fields which include biomaterials and tissue engineering. The properties of bone, muscles and tissues, the replacement of natural materials with artificial compatible and functional materials such as polymers, composites, ceramics and metals, and the complex interactions between implants and the body are studied at the tissue level. The emphasis of research is on the fundamental basis for diagnosis, disease treatment, and re-design of molecular, cellular, and tissue functions. In addition to quantitative experiments required to obtain spatial and temporal information, quantitative and integrative modeling approaches at the molecular, cellular, and tissue levels are also included within this field. Although some of the research will remain exclusively at one length scale, research that bridges any two or all three length scales are also an integral part of this field. Graduates of this program will be targeted principally for employment in academia, government research laboratories, and the biotechnology, pharmaceutical, and biomedical industries.