Effects of Advective-Diffusive Transport of Multiple Chemoattractants on Motility of Engineered Chemosensory Particles in Fluidic Environments.

Danielle King,Frank Healy,Hoa Nguyen,Melissa Whitman,Hakan Başağaoğlu,Sauro Succi

doi:10.3390/e21050465

Abstract

Motility behavior of an engineered chemosensory particle (ECP) in fluidic environments is driven by its responses to chemical stimuli. One of the challenges to understanding such behaviors lies in tracking changes in chemical signal gradients of chemoattractants and ECP-fluid dynamics as the fluid is continuously disturbed by ECP motion. To address this challenge, we introduce a new multiscale numerical model to simulate chemotactic swimming of an ECP in confined fluidic environments by accounting for motility-induced disturbances in spatiotemporal chemoattractant distributions. The model accommodates advective-diffusive transport of unmixed chemoattractants, ECP-fluid hydrodynamics at the ECP-fluid interface, and spatiotemporal disturbances in the chemoattractant concentrations due to particle motion. Demonstrative simulations are presented with an ECP, mimicking Escherichia coli (E. coli) chemotaxis, released into initially quiescent fluids with different source configurations of the chemoattractants N-methyl-L-aspartate and L-serine. Simulations demonstrate that initial distributions and temporal evolution of chemoattractants and their release modes (instantaneous vs. continuous, point source vs. distributed) dictate time histories of chemotactic motility of an ECP. Chemotactic motility is shown to be largely determined by spatiotemporal variation in chemoattractant concentration gradients due to transient disturbances imposed by ECP-fluid hydrodynamics, an observation not captured in previous numerical studies that relied on static chemoattractant concentration fields.

Highlights

Intellectual and technological advances in a variety of fields continue to refine our understanding of the principles and potential applications of nanorobotic systems
In modified RapidCell (MRC)-colloidal lattice Boltzmann (CLB)-advective-diffusive transport (ADT) simulations discussed in the subsequent sections, except for the validation test (Appendix A.1) and supplementary simulations (Appendix A.2) in Appendix, the fluid was initially quiescent and the fluid domain was bounded in all directions
We developed a new multiscale chemotactic motility model to investigate the behavior of engineered chemosensory particle (ECP) in dynamic fluidic environments with spatially and temporally-varying gradients of two chemoattractants in response to ECP motility

Summary

Introduction

Intellectual and technological advances in a variety of fields continue to refine our understanding of the principles and potential applications of nanorobotic systems. Of great interest in this area is the understanding and development of control systems through which nanorobotic devices or bacterial biohybrids carrying a payload can be effectively directed to a specified target. While the fluidic environment poses navigational challenges to device design in each of these areas [7], natural biological systems, which have undergone adaptation and evolutionary selection for optimized solutions to these issues, have provided insights and inspiration [8,9,10,11,12]. Bacterial cells have been engineered to target specific locations in animal systems, most notably cancer tissue [2,13,14,15]

Results

Discussion

Conclusion