Open Access

ABSTRACT

The Dependence of Diffusio-Phoretic Mobility and Aggregation Properties of Proteins on Intermolecular Interaction in Confined System

by Jiachen Wei

1 State Key Laboratory of Nonlinear Mechanics, Institute of Mechanics, Chinese Academy of Sciences, Beijing 100190, China
2 Department of Chemistry, University of Cambridge, Cambridge, CB2 1EW, United Kingdom
* Corresponding Author: Jiachen Wei. Email: weijiachen@lnm.imech.ac.cn.

Molecular & Cellular Biomechanics 2019, 16(Suppl.2), 103-104. https://doi.org/10.32604/mcb.2019.07721

Abstract

Phoretic flow can be generated by different types of gradient (e.g. temperature, concentration, or charge gradient) [1-3]. Within micro-to-nano confined system, the diffusio-phoretic property for proteins differs dramatically from that obtained in bulk condition, due to concentration fluctuation that emerges at microscopic level induced by specific and nonspecific interactions between protein and co-solute [4-5]. The phoretic mobility of protein individuals and complex in solute gradients can be theoretically described by continuum model [1-2] that neglects microscopic heterogeneity and determined experimentally by microfluidics [6], but the underlying mechanism of diffusio-phoretic motion for confined protein still remains unclear.
Our approach to this challenge is to combine real-time, label-free observations on microfluidic devices [7] and molecular dynamics simulations [8-9] driven by implicitly imposed forces, to analyze the time evolution of dynamics and distribution for proteins in solute gradients and determine the controlling parameters for diffusio-phoretic mobility. We also design a simple model of spherical colloid submerged and fixed in out-of-equilibrium fluid consisting of solute and solvent, to characterize the sensitive dependence of the rate of diffusio-phoretic flow created by the colloid on solute concentration and interaction strength at microscopic level. We present general features for the fluctuations of number and force density of fluid around the colloid. Suitable values of controlling parameters that maximize the diffusio-phoretic mobility are determined, which cannot be properly measured by traditional continuum approximations. The results explain the microscopic mechanism of diffusio-phoretic motion for proteins in confined system and the following focusing or aggregation that may lead to degenerative diseases like Alzheimer. It also helps to develop low-cost, high-precision microfluidic chips for protein separation and purification.

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