Bulletin of the American Physical Society
APS March Meeting 2023
Las Vegas, Nevada (March 5-10)
Virtual (March 20-22); Time Zone: Pacific Time
Session B13: Cells as active matter modifying their environment: from colloids to cancer
11:30 AM–2:30 PM,
Monday, March 6, 2023
Room: Room 238
Sponsoring Unit: DBIO
Chair: Brian Camley, Johns Hopkins University
Abstract: B13.00001 : Emergent behavior driven by self-generated gradients: from active droplets to bacterial suspension
11:30 AM–12:06 PM
Babak Vajdi Hokmabad
Babak Vajdi Hokmabad
In this talk, I will first discuss self-propelling droplets as a model for chemically active particles that modify their environment by leaving chemical footprints, which act as chemorepulsive signals to other droplets. I will present our analysis of this communication mechanism quantitatively both on the scale of individual agent–trail collisions as well as on the collective scale where droplets actively remodel their environment while adapting their dynamics to that evolving chemical landscape. We show in experiment and simulation how these interactions cause a transient dynamical arrest in active emulsions where swimmers are caged between each other’s trails of secreted chemicals. These findings yield principles for predicting how negative autochemotaxis shapes the navigation strategy of chemically active particles.
Next, I will discuss the dynamics of aerobic bacterial suspensions that are confined in tight spots where oxygen availability is spatially variable. In such systems, the cellular motility is coupled to the local oxygen concentration. We show that bacteria collectively consume oxygen, generate an oxygen gradient, and then respond to it by separating into two distinct aerobic and anaerobic phases.
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