In biological systems, electrons, energy, and information “flow” through the redox modality, and we ask, does biology have redox capacitor capabilities for storing electrons? We describe emerging evidence indicating that biological phenolic/catecholic materials possess such redox capacitor properties. We further describe results that show biomimetic catecholic materials are reversibly redox-active with redox potentials in the midphysiological range and can repeatedly accept electrons (from various reductants), store electrons, and donate electrons (to various oxidants). Importantly, catechol-containing films that are assembled onto electrode surfaces can enhance the flow of electrons, energy, and information. Further, catechol-containing films can serve as redox-based interactive materials capable of actuating biological responses by turning on gene expression from redox-responsive genetic circuits. Looking forward, we envision that the emerging capabilities for measuring dynamic redox processes and reversible redox states will provide new insights into redox biology and will also catalyze new technological opportunities for information processing and energy harvesting.
", "doi": "10.1021/acsami.4c13032", "issn": "1944-8244", "publisher": "American Chemical Society", "publication": "ACS Applied Materials & Interfaces", "publication_date": "2024-11-13", "series_number": "45", "volume": "16", "issue": "45", "pages": "61495\u201361502" }, { "id": "authors:s9y1r-vce93", "collection": "authors", "collection_id": "s9y1r-vce93", "cite_using_url": "https://authors.library.caltech.edu/records/s9y1r-vce93", "type": "article", "title": "Redox active plant phenolic, acetosyringone, for electrogenetic signaling", "author": [ { "family_name": "Zakaria", "given_name": "Fauziah Rahma", "clpid": "Zakaria-Fauziah-Rahma" }, { "family_name": "Chen", "given_name": "Chen-Yu", "orcid": "0000-0001-6500-6970", "clpid": "Chen-Chen-Yu" }, { "family_name": "Li", "given_name": "Jinyang", "orcid": "0000-0003-3190-4021", "clpid": "Li-Jinyang" }, { "family_name": "Wang", "given_name": "Sally", "orcid": "0000-0001-9668-888X", "clpid": "Wang-Sally" }, { "family_name": "Payne", "given_name": "Gregory F.", "orcid": "0000-0001-6638-9459", "clpid": "Payne-Gregory-F" }, { "family_name": "Bentley", "given_name": "William E.", "orcid": "0000-0002-4855-7866", "clpid": "Bentley-William-E" } ], "abstract": "Redox is a unique, programmable modality capable of bridging communication between biology and electronics. Previous studies have shown that the E. coli redox-responsive OxyRS regulon can be re-wired to accept electrochemically generated hydrogen peroxide (H2O2) as an inducer of gene expression. Here we report that the redox-active phenolic plant signaling molecule acetosyringone (AS) can also induce gene expression from the OxyRS regulon. AS must be oxidized, however, as the reduced state present under normal conditions cannot induce gene expression. Thus, AS serves as a “pro-signaling molecule” that can be activated by its oxidation—in our case by application of oxidizing potential to an electrode. We show that the OxyRS regulon is not induced electrochemically if the imposed electrode potential is in the mid-physiological range. Electronically sliding the applied potential to either oxidative or reductive extremes induces this regulon but through different mechanisms: reduction of O2 to form H2O2 or oxidation of AS. Fundamentally, this work reinforces the emerging concept that redox signaling depends more on molecular activities than molecular structure. From an applications perspective, the creation of an electronically programmed “pro-signal” dramatically expands the toolbox for electronic control of biological responses in microbes, including in complex environments, cell-based materials, and biomanufacturing.
\nElectrode-imposed electronic inputs can generate various cues that can control the emergence of hierarchical structure and confer function to hydrogel systems. Here we describe three such top-down cues. Electrolytic reactions can create pH cues that can induce the electrodeposition of pH-responsive self-assembling polymers (e.g., chitosan and alginate). The electric field provides a long-range cue that can induce polymer chains to migrate toward (or away from) the electrode and can align the polymer chains within the assembling hydrogel network (e.g., collagen). The electrochemical generation of diffusible oxidants provides a molecular cue that can induce oxidative assembly - typically through the formation of covalent bonds (e.g., disulfide bonds). Here, we review recent results on the use of these three cues for the electrofabrication of hydrogels and we illustrate how complementary capabilities from biotechnology allow the creation of functional hydrogel systems. Overall, we envision that electro-bio-fabrication could emerge as a scalable additive manufacturing method as well as a flexible approach for distributed manufacturing in public maker spaces.
", "doi": "10.1016/j.matlet.2023.135497", "issn": "0167-577X", "publisher": "Elsevier", "publication": "Materials Letters", "publication_date": "2024-01-15", "volume": "355", "pages": "135497" } ]