Mimicking biology’s sulfur switching mechanism for redox signal reception

Abstract

Bridging communication between biology and electronics is critically dependent on the modality. There have been remarkable successes in bio-device communication through the electrical modality associated with the flow of ions across cellular membranes because this modality is integral to communication in biology (e.g., in neuromuscular systems) and this modality is readily accessible to convenient electrode measurements. There has been considerably less success in establishing bio-device communication through molecularly-specific biological modalities because of the intrinsic measurement challenges. We are focused on a third modality associated with reduction and oxidation (redox) reactions. From a biological perspective, this redox modality is integral to immune responses and wound healing, and even appears to inter-connect biological systems (e.g., the gut-brain axis) and biological kingdoms (e.g., the gut microbiome and epithelium). From a technological perspective, this redox modality has global electrical features that are accessible to convenient electrode measurements. Further, this redox modality has molecular features that offer some level of selectivity to redox-based bio-device communication. Here, we focus on a single mechanism integral to biological redox-based signal processing - the oxidative switching of thiols to disulfides. Biology uses this sulfur switching for the redox-responsive expression of genes associated with stress responses. Using model polymers, we show that electrochemical inputs can be used to induce redox-based sulfur switching. Experimental results demonstrate that variations in the “strength” (i.e., voltage) of the redox input signal can lead to qualitatively and quantitatively different responses in polymer assembly. Potentially, these observations recapitulate the redox-responsive sulfur switching that alters the permeability of mucous membranes.