Porous monolith microfluidics for bacterial cell-to-cell communication assays

Abstract

Genetically engineered bacteria can be used for a wide range of applications, from monitoring environmental toxins to studying complex communication networks in the human digestive system. Although great strides have been made in studying single strains of bacteria in well-controlled microfluidic environments, there remains a need for tools to reliably control and measure communication between multiple discrete bacterial populations. Stable long-term experiments (e.g., days) with controlled population sizes and regulated input (e.g., concentration) and output measurements can reveal fundamental limits of cell-to-cell communication. In this work, we developed a microfluidic platform that utilizes a porous monolith to reliably and stably partition adjacent strains of bacteria while allowing molecular communication between them for several days. We measured small molecule production by the bacterial populations in response to stimuli using analytical chemistry methods and measured fluorescent output. The results are compared with communication and diffusion delay models. This porous monolith microfluidic system enables bacterial cell-to-cell communication assays with dynamic control of inputs, relatively long-term experimentation with no cross contamination, and stable bacterial population size. This system can serve as a valuable tool in understanding bacterial communication and improving biosensor design capabilities.

Microfluidic Systems for Molecular Communications: A Review From Theory to Practice

“…This model, considering factors like biofilm encapsulation and oxygen concentration, advances the design of bacteria-based sensors, enhancing environmental monitoring and healthcare applications. Further, in a later study [56], the same research group developed a microfluidic platform using a porous monolith to study communication between multiple bacterial strains. This system allowed for controlled, long-term experiments, shedding light on the fundamental limits of cell-to-cell communication and its implications for biosensor development.…”

Experimental Research in Synthetic Molecular Communications -- Part I: Overview and Short-Range Systems

“…AHL-based communication between bacteria colonies: In [39], the communication between two bacteria colonies on a microfluidic chip in response to an external input signal was studied. To this end, a Tx and an Rx bacteria colony, respectively, were grown in two distinct trapping chambers on the chip.…”

“…Upon stimulation of the Tx colony, the AHL molecules produced by the Tx colony propagated through the porous barrier between the Tx and the Rx chambers via diffusion. In this setting, externally controlled bacteria-to-bacteria communication could be observed experimentally in [39].…”

Fore-aft clearance controls how three-dimensional confinement affects micropropulsion

“…Active particles often move through complex media that are not simple Newtonian fluids, both in natural [19][20][21][22][23][24][25] and laboratory [26][27][28][29][30] environments, including many situations where geometrical confinement becomes important. For example, bacteria can have altered trajectories [31,32] and accumulate when swimming along boundaries [33][34][35][36], including in naturally arising situations such as oil drops [37][38][39], while engineered boundaries can be designed with complex shapes to guide and collect bacteria [40][41][42] and sperm [43][44][45][46] along them.…”