**4. Bridging the bio-electro interface: Redox signaling and electrogenetic systems**

In addition to quorum sensing, bacteria use numerous other small chemical molecules to build up conversations between themselves and with the environment. It is well known that redox reactions and redox based signaling pervade living cells and are extremely crucial to both anabolic and catabolic metabolism. Redox-based molecular systems, however, are also leveraged by bacteria for communication. Cells must detect a variety of oxidative stressors and quickly respond so as to avoid oxidative damage and maintain redox balance in order to survive. In this section, several redox signaling pathways will be introduced, yet emphasis will be on how redox signaling and electrochemistry help connect communication and information transfer between biological systems and electronic devices. In this way, redox molecules can serve as exogenous and electronically-programmed controllers of biological function.
