Cells provide an isolated, controlled environment for carrying out complex chemical reactions. Moreover, they reproduce themselves, allowing the creation of many copies with little manufacturing effort. The ability to control cellular function will provide important capabilities in computation, materials manufacturing, sensing, effecting, and fabrication at the molecular scale.
This work is part of an effort to learn how to control the chemical mechanisms of the cell, by co-opting the existing biological mechanism and by constructing novel mechanism. One particular short-term goal is to engineer chemical mechanisms which can be used to implement the digital abstraction--the notion that chemical signals can represent logical true and false (or zero and one) values.
Like any good abstraction, the digital abstraction allows us to ignore the fine details of a complex phenomenon, and concentrate on the essentials of the control process.
The essential features of any digital logic implementation include the ability to distinguish and maintain two distinct values of some physical representation of a signal. This requires the presence of adequate noise margins--an ability to produce outputs whose physical values more perfectly represent a given logical value than the physical representation of their input. Adequate noise margins allow noise and imperfections in a digital system to be reduced, rather than amplified, during complex information processing.
This work attempts to define a series of biologically plausible chemical reactions which can implement such a digital abstraction.