Catechol-Based Molecular Memory Film for Redox Linked Bioelectronics

Redox is emerging as an alternative modality for bio-device communication. In contrast to the more familiar ionic electrical modality: (i) redox involves the flow of electrons through oxidation-reduction reactions; (ii) the aqueous medium is an insulator to this electron flow since free electrons do not normally exist in water; and (iii) redox states are intrinsically digital (oxidized and reduced). By exploiting these unique features, a catechol-based molecular memory film is reported. This memory is fabricated by electrochemically grafting catechol to a chitosan-agarose polysaccharide network to generate a redox-active but non-conducting matrix. The redox state of the grafted catechol moieties serves as the 2-state memory. It is shown that these redox states: can be repeatedly switched by diffusible mediators (electron shuttles); can be easily read electrically or optically; are stable for at least 2 h in the absence of energy; are sensitive to biologically relevant oxidizing and reducing contexts; and can be switched enzymatically. This catechol-based molecular memory film is a simple circuit element for redox linked bioelectronics.