Microscale diffusiophoresis of proteins

Abstract

Living systems are characterised by their spatially highly inhomogeneous nature which is susceptible to modify fundamentally the behaviour of biomolecular species, including the proteins that underpin biological functionality in cells. Spatial gradients in chemical potential are known to lead to strong transport effects for colloidal particles, but their effect on molecular scale species such as proteins has remained largely unexplored. Here we demonstrate with microfluidic measurements that individual proteins can undergo strong diffusiophoretic motion in salt gradients in a manner which is sufficient to overcome diffusion and lead to dramatic changes in their spatial organisation on the scale of a cell. Moreover, we demonstrate that this phenomenon can be used to control the motion of proteins in microfluidics devices. These results open up a path towards a physical understanding of the role of gradients in living systems in the spatial organisation of macromolecules and highlight novel routes towards protein sorting applications on device.

Diffusiophoresis, Diffusioosmosis, and Microfluidics: Surface-Flow-Driven Phenomena in the Presence of Flow

“…The authors provided an estimation of the zeta potential and mentioned potential microfluidic application using MgCl 2 . One-dimensional diffusiophoresis of bovine serum albumin (BSA), β-lactoglobulin, myoglobin, and lysozyme under gradient of LiCl, KCl, and KIO 2 are also demonstrated by Peter et al using a dead-end pore geometry (Figure ).…”

“…A microfluidic approach for diffusiophoresis of macromolecules is demonstrated by Palacci et al for DNA focusing, , and later more groups visualized and studied diffusiophoresis of lipid vesicles, DNA, proteins, and other macromolecules. ,,,− ,− In the studies by Palacci et al, , under a concentration gradient of LiCl set up across the flow, colloidal particles and λ-DNA showed transient diffusiophoretic focusing. The measurements and calculations for the peak propagation indicated that fluorescent-tagged λ-DNA behaves similarly to the polystyrene particles (carboxylate-modified PS; d = 200 nm).…”

“…Diffusiophoresis of protein in the dead-end pore geometry and detection of fluorescent intensity. Images reproduced from ref with permission.…”

“…A dead-end pore has been used to demonstrate various transport behaviors along a one-dimensional solute gradient (Figure ). − ,,,,,− As described above, H-shaped channels with open-end pores can also generate a one-dimensional concentration gradient of solutes. In the H-channel, a steady-state concentration gradient can be set up, which generates constant diffusioosmotic velocity along the wall.…”