Hydrogel Patterning with Catechol Enables Networked Electron Flow

Abstract

Reduction–oxidation (redox) reactions provide a distinct modality for biological communication that is fundamentally different from the more‐familiar ion‐based electrical modality. Biology uses these two modalities for communication through different systems (immune versus nervous), and uses different mechanisms to control the flow of the charge carriers: the flow of soluble ions is controlled using structural barriers (i.e., membranes) and gates (e.g., membrane‐spanning protein channels), while the flow of insoluble electrons is controlled using redox‐reaction networks. Here, a simple electrochemical approach to pattern catechols onto a flexible polysaccharide hydrogel is reported and it is demonstrated that the patterned catechol regions serve as nodes for the mediated flow of electrons through redox reactions. Electron flow through this node involves the switching of binary redox states (oxidized and reduced) and this node's redox state can be detected (i.e., “read”) by passively observing its optical absorbance, or actively switching its redox‐state electrochemically. Further, this catechol node can be switched through biological mechanisms, and this enables the fabricated catechol node to be embedded within biochemical redox reaction networks to facilitate the spanning of bio‐electronic communication. Thus, it is envisioned that catechols can emerge as a molecular equivalent to a transistor for miniaturize‐able, deployable and sustainable redox‐linked bioelectronics.

Redox Host–Guest Nanosensors Installed with DNA Gatekeepers for Immobilization‐Free and Ratiometric Electrochemical Detection of miRNA

“…Such narrow E g implied the π‐electron delocalization over MPDA, which benefited the electron generation after absorbing photons. [ 19b ] In addition, the highest occupied molecular orbital (HOMO) was measured by the CV method with ferrocene/ferrocenium (Fc/Fc + ) couple as an internal reference. [ 26 ] As shown in Figure 2b, HOMO and lowest unoccupied molecular orbital (LUMO) of MPDA were calculated to be −3.80 and −3.17 eV, respectively ( E Fc/Fc+ was calculated to be 0.59 V versus Ag/AgCl in Figure S5, Supporting Information).…”

“…[ 17 ] More importantly, the progressive assembly of electroactive dopamine [ 18 ] endow PDA with redox activity as electrochemical signal probes. Additionally, due the nature of PDA as organic semiconductor, [ 19 ] the photoinduced electrons can be utilized to boost its signal as a reference.…”

Intervention of Polydopamine Assembly and Adhesion on Nanoscale Interfaces: State‐of‐the‐Art Designs and Biomedical Applications

“…For example, the redox-active properties have been explored in the construction of batteries to power medical devices, [187,188] redox mediators to boost ROS generation catalysis, [189] as well as electrochemical transistors for sensing of biochemical markers. [190,191] Rendering the materials with large surface areas and highly exposed catechol/quinone sites by the aforementioned strategies may potentially improve interface process-relevant/dominant properties in these applications. The relationship between nanoscale assembly/aggregation manipulation and the electrochemical properties may lead to various figures of merit.…”

Electrochemical Glue for Binding Chitosan–Alginate Hydrogel Fibers for Cell Culture

“…Electrochemically generated chemicals have also been utilized to modify cell culture surfaces locally using a scanning electrochemical microscope [ 42 , 43 , 44 ], resulting in cell patterning during culture. In another study, catechol was electrochemically patterned on hydrogels [ 45 ]. An electrodeposition method was applied for the fabrication of porous Janus films [ 39 ].…”