3D Printed Spectroelectrochemical Platform for Redox-Based Bioelectronics

Redox provides unique opportunities for interconverting molecular/biological information into electronic signals. Here, the fabrication of a 3D-printed multiwell device that can be interfaced into existing laboratory instruments (e.g., well-plate readers and microscopes) to enable advanced redox-based spectral and electrochemical capabilities is reported. In the first application, mediated probing is used as a soft sensing method for biomanufacturing: it is shown that electrochemical signal metrics can discern intact mAbs from partially reduced mAb variants (fragmentation), and that these near-real-time electrical measurements correlate to off-line chemical analysis. In the second application, operando spectroelectrochemical measurements are used to characterize a redox-active catechol-based hydrogel film: it is shown that electron transfer into/from the film correlates to the molecular switching of the film's redox state with the film's absorbance increasing upon oxidation and the film's fluorescence increasing upon reduction. In the final example, a synthetic biofilm containing redox-responsive E. coli is electro-assembled: it is shown that gene expression can be induced under reducing conditions (via reductive H₂O₂ generation) or oxidative conditions (via oxidation of a phenolic redox-signaling molecule). Overall, this work demonstrates that 3D printing allows the fabrication of bespoke electrochemical devices that can accelerate the understanding of redox-based phenomena in biology and enable the detection/characterization redox activities in technology.