Ankur Gupta, Department of Chemical and Biological Engineering, University of Colorado Boulder

Gradient-Driven Transport Phenomena: From Fish Skin Patterns to Exclusion Zone Formation Near Robbit Cornea

This seminar will discuss our research group's work on diffusiophoresis, focusing on its potential role in biological pattern formation, a phenomenon we have termed diffusiophoresis-enhanced Turing patterns (DETPs). Diffusiophoresis is a transport process where a colloidal particle advects due to gradients of dissolved solute species. Specifically, we employed reaction-diffusion-diffusiophoresis models to show how DETPs can accurately reproduce skin patterns in vertebrates with a striking resemblance. We also perform linear stability analysis and show that the Peclet number controls the wavelength of these patterns. This work opens a new avenue of research, where diffusiophoresis can be harnessed to assemble cells in the presence of a chemical gradient. The formation of an exclusion zone near surfaces was first discovered in the field of physiology, where the exclusion zone was observed next to a rabbit cornea. Until recently, there was little consensus about the origin of this phenomenon. We reproduce some recent experimental results that demonstrate that diffusiophoresis is the reason behind this exclusion zone formation. By developing reaction-diffusion-diffusiophoresis models for multi-ion systems, which lead to coupled transport equations between species, we show that diffusiophoresis can be used to trigger hydrodynamic instabilities. Our simulation model qualitatively reproduces key experimental observations and enables systematic exploration of how diffusiophoresis is present in biological systems, and can potentially influence flow patterns and induce mixing.