title: Significance of thermal fluctuations and hydrodynamic interactions in receptor-ligand-mediated adhesive dynamics of a spherical particle in wall-bound shear flow.
abstract: The dynamics of adhesion of a spherical microparticle to a ligand-coated wall, in shear flow, is studied using a Langevin equation that accounts for thermal fluctuations, hydrodynamic interactions, and adhesive interactions. Contrary to the conventional assumption that thermal fluctuations play a negligible role at high Péclet numbers, we find that for particles with low surface densities of receptors, rotational diffusion caused by fluctuations about the flow and gradient directions aids in bond formation, leading to significantly greater adhesion on average, compared to simulations where thermal fluctuations are completely ignored. The role of wall hydrodynamic interactions on the steady-state motion of a particle, when the particle is close to the wall, has also been explored. At high Péclet numbers, the shear induced force that arises due to the stresslet part of the Stokes dipole plays a dominant role, reducing the particle velocity significantly and affecting the states of motion of the particle. The coupling between the translational and rotational degrees of freedom of the particle, brought about by the presence of hydrodynamic interactions, is found to have no influence on the binding dynamics. On the other hand, the drag coefficient, which depends on the distance of the particle from the wall, plays a crucial role at low rates of bond formation. A significant difference in the effect of both the shear force and the position-dependent drag force on the states of motion of the particle is observed when the Péclet number is small.
authors.affiliation: IITB-Monash Research Academy, Indian Institute of Technology, Mumbai, India.
authors.forename: K V
authors.initials: KV
authors.lastname: Ramesh
authors.affiliation: Department of Chemical Engineering, Indian Institute of Technology, Mumbai, India.
authors.forename: R
authors.initials: R
authors.lastname: Thaokar
authors.affiliation: Department of Chemical Engineering, Monash University, Clayton, Australia.
authors.forename: J Ravi
authors.initials: JR
authors.lastname: Prakash
authors.affiliation: Department of Mechanical & Aerospace Engineering, Monash University, Clayton, Australia.
authors.forename: R
authors.initials: R
authors.lastname: Prabhakar
mesh_terms: D000465:Algorithms; D003198:Computer Simulation; D004058:Diffusion; D057446:Hydrodynamics; D009038:Motion; D013816:Thermodynamics