Biocomputers: from test tubes to live cells.

Biocomputers are man-made biological networks whose goal is to probe and control biological hosts--cells and organisms--in which they operate. Their key design features, informed by computer science and engineering, are programmability, modularity and versatility. While still a work in progress, biocomputers will eventually enable disease diagnosis and treatment with single-cell precision, lead to "designer" cell functions for biotechnology, and bring about a new generation of biological measurement tools. This review describes the intellectual foundation of the "biocomputer" concept as well as surveys the state of the art in the field.