Non-Brownian Interfacial Diffusion: Flying, Hopping, and Crawling

Abstract

In theoretical work beginning in the 1990s, O'Shaughnessy and co-workers predicted that for lateral diffusion at a solid-liquid interface, a key step involves desorption, excursion through the liquid phase, and readsorption to the interface. This step was expected to dominate twodimensional surface diffusion over certain time scales, leading to anomalous diffusion; in practice, such liquid-phase excursions could significantly impact the efficiency and kinetics of interfacial processes. In this contribution, we emphasize the application of single-molecule methods in exploring the characteristics, influential factors, mechanisms, and consequences of anomalous interfacial diffusion and discuss possible ways to control the elementary processes of desorption-mediated anomalous diffusion. It is hoped that the insights provided from understanding these elementary processes will enable researchers to exploit and control intermittent hopping in applications involving interfacial diffusion, such as surface reactions, molecular recognition, and surface biocompatibility.

Two-Dimensional Interfacial Exchange Diffusion Has the Potential to Augment Spatiotemporal Precision of Ca2+ Signaling

“…Due to the novelty of this concept, there are currently no experimental or computational tests reported with respect to the biological implications of 2D Ca 2+ exchange diffusion, specifically for its role in junctional Ca 2+ signaling. On the other hand, non-Brownian interfacial diffusion has been intensively studied in physical chemistry, using state-of-the-art techniques of single-molecule tracking and dynamic modeling [ 15 ]. A complex process of “Continuous Time Random Walk” (CTRW), which contains elements of “flying, hopping and crawling” and combines random-walk 3D diffusion, adsorption and desorption as well as 2D surface diffusion, has been well documented.…”

Lateral diffusion of single poly(ethylene oxide) chains on the surfaces of glassy and molten polymer films

“…Nevertheless, the relative contributions of adsorption and desorption are important in some diffusion mechanisms. 52,53 Figure 4: FFM data reveal that a peak in the coefficient of friction of a silicon nitride AFM tip on a PEMA surface. The friction data are normalized to the result at 313 K Both poly(alkyl methacrylate) films and the native oxide layer of silicon surfaces offer hydrogen bonding sites with which the PEO can interact.…”

Stochastic Adsorption of Diluted Solute Molecules at Interfaces

“…1), is fundamentally relevant in many fields such as cell biology, biosensing, separation, fluidic dynamics, reaction kinetics, catalysis, and batteries. [1][2][3][4][5][6][7][8][9] The ensemble kinetics of diffusion has been summarized by Fick's laws of diffusion. 2,3 For example, the diffusion of materials in a diluted solution from a high-concentration reservoir into a tubing space forms a time-and space-dependent concentration gradient function C(x, t), 2,3 (1…”

“…7,16 The adsorption of the molecules is greatly affected by the reabsorption of the reflected molecules. 8 It is becoming important for us to re-evaluate the theory of adsorption under ideal conditions to reduce the difficulty in building or understanding more complicated models.…”