Redox Is a Global Biodevice Information Processing Modality

Biology is well known for its ability to communicate through molecularly specific signaling modalities and a globally acting electrical modality associated with ion flow across biological membranes. Emerging research suggests that biology uses a third type of communication modality associated with a “flow” of electrons through reduction/oxidation (redox) reactions. This redox signaling modality appears to act globally and has features of both molecular and electrical modalities: since free electrons do not exist in aqueous solution, the electrons must “flow” through molecular intermediates that can be switched between two states—with electrons (reduced) or without electrons (oxidized). Importantly, this global redox modality is easily accessible through its electrical features using convenient electrochemical instrumentation. In this review, we explain this redox modality, describe our electrochemical measurements, and provide four examples demonstrating that redox enables communication between biology and electronics. The first two examples illustrate how redox probing can acquire biologically relevant information. The last two examples illustrate how redox inputs can transduce biologically relevant transitions for patterning and the induction of a synthetic biology (synbio) “transceiver” for two-hop molecular communication. In summary, we believe redox provides a unique ability to bridge biodevice communication because simple electrochemical methods enable global access to biologically meaningful information. Furthermore, we envision that redox may facilitate the application of information theory to the biological sciences.