Lateral Diffusion from Ligand Dissociation and Rebinding at Surfaces

Abstract

The lateral diffusion coefficient of a ligand which repeatedly dissociates and rebinds to sites on a planar surface is described. An analytical expression showing the manner in which the diffusion coefficient depends on the propensity for rebinding after dissociation, as the molecule moves through the solution and across the surface, is derived. The diffusion coefficient is time dependent and ranges from the surface diffusion coefficient (at time zero when a tagged molecule is placed on the surface) to the solution diffusion coefficient (at time infinity). The time-dependent diffusion coefficient depends only on the intrinsic dissociation rate and a "rebinding parameter", which in turn depends on a group of constants including the intrinsic association and dissociation rates, the density of unoccupied surface binding sites, and the diffusion coefficient in solution.

Single Molecule Observations of Desorption-Mediated Diffusion at the Solid-Liquid Interface

“…The mobility of molecules at the solid-liquid interface is of critical importance to several applications of surface science, including self-assembled monolayer growth [1,2], surface reactivity [3,4], and molecular recognition associated with both biomembranes and biosensors [5][6][7]. In these applications, a fundamental issue involves the way in which a molecule identifies a target on a surface.…”

“…The larger diffusion coefficient allows the molecules to ''explore'' larger areas of the surface to find a target. With increasing solute concentrations, adsorption or desorption rates will become increasingly important; however, previous theoretical work suggests that surface diffusion still remains a critically important factor in determining the efficiency of targeting under relevant conditions [6,7]. Also, even at arbitrarily high solute concentrations, the flying mode will still increase the rate of any kinetic process in which surface diffusion is important, such as in the formation of selfassembled monolayers [1,2].…”

Detection of enzyme-catalyzed polysaccharide synthesis on surfaces

“…The binding of the enzyme to the surface could be either productive or unproductive in terms of the potential for catalysis. It is also possible for lateral diffusion to occur across the surface (Gaspers et al 1994;Trigiante et al 1999;Lieto et al 2003;Roy et al 2005), which could either be kinetically beneficial or not, depending on the nature of the system.…”

“…There have been other reports that enzymes turn over slower on a surface than in solution Halling et al 2005). The two most common explanations are twodimensional lateral transfer diffusion rate limitation and an equilibrium between unproductive and productive binding (Gaspers et al 1994;Trigiante et al 1999;Lieto et al 2003;Lee et al 2005;Roy et al 2005). The latter seems most likely in our system because the enzyme could bind to the carboxylmethyl dextran chip in three possible modes: electrostatically to the carboxymethyl groups, perhaps in a non-productive mode to the dextran main chain, or productively to a non-reducing end of the dextran.…”

Manipulating and probing the spatio-temporal dynamics of nanoparticles near surfaces

“…However, the detection volume of TIR-FCS is defined by the depth of the evanescent field, which provides several times higher resolution along the z-axis (~100 nm) as compared with the conventional approach with a pinhole (~1 m). Because of its advantage of greater discrimination along the z-axis, TIR-FCS has been used to measure diffusion of proteins close to biomembranes and the kinetics of ligands binding to their receptors [14,15].…”