Bioelectronic Delivery of Ions and Small Molecules Modulates Growth in Bacteria Biofilms

Electrochemical and ionic signaling play key roles in regulating bacterial biofilm growth, spatial organization, and collective behavior. Delivering these signals with spatiotemporal control can enable biofilm engineering and interrogate fundamental processes. Here, we employ bioelectronic ion pumps to deliver ions and small molecules to Bacillus subtilis biofilms with spatiotemporal control. We deliver inorganic metal ions (Ag + , Cu ++ , Zn ++ ), a small-molecule drug (fluoxetine + ), and a neuroactive amino acid (GABA + ). We compare bioelectronic delivery with solution-based delivery. Because the cation-exchange membrane transports only positively charged species, bioelectronic delivery introduces the target cation alone, without its counterion and without any added bulk fluid, and reproduces the biological response obtained by pipetting while delivering roughly an order of magnitude less material. We demonstrate that bioelectronic delivery can enhance or inhibit growth of the films in the desired direction. We demonstrate proof-of-concept patterning by enhancing film growth in one direction and inhibiting film growth in the opposite direction. Our results demonstrate that bioelectronic delivery can be used to modulate the growth of bacteria biofilms.