Fig. 2: Electro-biofabrication for assembly of biological components and integration with an optoelectrochemical electronic system.
a Schematic of PEG-SH oxidative cross-linking, assembly of HRP-conjugated gelatin hydrogel (enzyme assembly), and co-deposition of E. coli and PEG-SH (cell assembly). Redox mediators, Ir and Fc, facilitates the oxidation and subsequent gelation of gelatin and PEG-SH. b Spatially-programmable deposition. (i) Fluorescence microscopy images of ‘artificial biofilms’ containing SYTO-9 dyed E. coli BL21 assembled onto circular 2 mm-diameter, square 5 × 5 mm, and square 10 × 10 mm gold electrodes. (ii) Activity of electroassembled HRP, represented as the absorbance at 405 nm through ABTS assay. (iii) Secreted AI-2 activity from electroassembled ‘artificial biofilms’ containing E. coli BL21 cells (OD600 = 5). Data are presented as mean (n = 2); open circles represent individual replicates. c Representative Z-stack confocal images of the ‘artificial biofilms’ containing GFP-expressing E. coli (DH5α-sfGFP). Deposition time is labeled on top of each image. X-axis (yellow), Y-axis (red), Z-axis and scale bars (white) are shown, all units are in μm. d ITO-based, 3D-printed optoelectrochemical device. Clear ITO glass: working electrode and allows for optical observations. Ag/AgCl electrode: reference electrode. Pt wire (below, mounted on custom-fabricated connector): counter electrode. The three electrodes are connected through the salt bridge (1 M KCl in 1% agarose) casted in the central well of the device. e Peroxide (H2O2) generated (blue) in the ITO-based electrochemical platform as correlated to applied charge (orange). Peroxide data are presented as mean±s.d. (n = 4, individual replicates shown in open circles). f Current obtained during peroxide generation. Working electrode (WE) was poised at −0.8 V for 300 s for all samples. Teal: 20% LB. Orange: 20% LB submerging a cell-free PEG-SH film deposited on WE. Blue: 20% LB submerging an ‘artificial biofilm’ containing E. coli (OD600 = 6) after 1.5 h of incubation at 34 °C. Purple: 0.4 ft3 h−1 of O2 supplied (starting at 0 s, through built-in tubing in the connector) to 20% LB submerging an ‘artificial biofilm’ containing E. coli (OD600 = 6) after 1.5 h of incubation at 34 °C.
