Modularity, context-dependence, and insulation in engineered biological circuits

•Insulation of parts and functional modules from their context is a major challenge.•Parts engineering and circuit design are both important in solving context-dependence.

The ability to link systems together such that they behave as predicted once they interact with each other is an essential requirement for the forward-engineering of robust synthetic biological circuits. Unfortunately, because of context-dependencies, parts and functional modules often behave unpredictably once interacting in the cellular environment. This paper reviews recent advances toward establishing a rigorous engineering framework for insulating parts and modules from their context to improve modularity. Overall, a synergy between engineering better parts and higher-level circuit design will be important to resolve the problem of context-dependence.