(114e) Towards Understanding Collaborative Networks of Bacteriabots: High-Throughput Characterization of Quorum-Sensing in Bacteria

The innate ability of pathogens to evade immune response and invade target cells is very attractive for designing bacterial/viral-based drug delivery carriers. Thus, numerous efforts have been made to use bacteria and viruses for therapeutic delivery. We have previously developed micro and nanoscale bacteria-based bio-hybrid drug delivery systems, called BacteriaBots, through interfacing live genetically modified disease-targeting bacteria with polymeric micro/nano-particles. Several bacterial species produce and respond to signaling molecules, called autoinducers, in order to effectively communicate information with each other and/or monitor the transport properties of their immediate environment through a process termed quorum sensing (QS). This phenotypic behavior of bacteria can be exploited for generating a mobile network of BacteriaBots with the ability to accomplish cooperative theranostic tasks autonomously at the target site. Each BacteriaBot is a simple bio-hybrid system with limited capabilities; thus, QS regulated responses of bacteria are essential to cooperative task completion by a swarm of BacteriaBots. Engineered bacteria containing QS-based genetic circuits have been used as bioreporters for quantifying autoinducer concentrations. Although using such bioreporters leads to characterization of QS response with a higher sensitivity compared to conventional analytical methods, a high-throughput system that can thoroughly characterize the QS response of a bioreporter to a range of autoinducer concentrations is still missing. In this work, we fabricated a microfluidic device in Polydimethylsiloxane (PDMS) to quantify the QS response of a model bioreporter to a wide range of exogenous autoinducer concentrations in a single experiment. To make the bioreporter, Escherichia coli MG1655 was transformed with the pLVA01 plasmid construct (Ap^r; pUC18Not-luxR-P_luxI-RBSII-gfp(LVA)-T₀-T₁). The fabricated microfluidic diffusive mixer was used to establish a close to linear gradient of exogenous 3-oxo-C6-homoserine lactone molecules for a layer of bacteria attached on the bed of the device and quantify the QS response of bacteria. Also, the QS response of BacteriaBots has been characterized to indicate the results obtained from a large bacterial population can serve as a robust predictive tool for the small bacterial population attached to particles.