Tuning the Flight Length of Molecules Diffusing on a Hydrophobic Surface

Mabry, Joshua N.; Schwartz, Daniel K.

doi:10.1021/acs.jpclett.5b00799

“…the distributions were broader) on surfaces corresponding to a stronger adsorbate-surface interaction. Previous work has suggested that surface diffusion was influenced by multiple effects, e.g., adsorbate-surface interactions (desorption rate), re-adsorption probability, physical obstacles, chemical surface heterogeneity, etc [24,[39][40][41][42][43]. The results presented here provide a comprehensive picture of how and why adsorbate-surface interactions influence interfacial motion.…”

mentioning

confidence: 66%

“…For example, theoretical models represent a flight as a series of hops (i.e. returns to the surface), where a molecule may stochastically re-adsorb after a given hop according to a hypothetical parameter known as the "sticking coefficient" [27]. While this parameter is theoretically the primary determinant of the flight-length, to date there has been no actual support for the presence of multiple hops per flight.…”

mentioning

confidence: 99%

Three-Dimensional Tracking of Interfacial Hopping Diffusion

Wang

¹

,

Wu

²

,

Schwartz

³

2017

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Theoretical predictions have suggested that molecular motion at interfaces-which influences processes including heterogeneous catalysis, (bio)chemical sensing, lubrication and adhesion, and nanomaterial self-assembly-may be dominated by hypothetical "hops" through the adjacent liquid phase, where a diffusing molecule readsorbs after a given hop according to a probabilistic "sticking coefficient." Here, we use three-dimensional (3D) single-molecule tracking to explicitly visualize this process for human serum albumin at solid-liquid interfaces that exert varying electrostatic interactions on the biomacromolecule. Following desorption from the interface, a molecule experiences multiple unproductive surface encounters before readsorption. An average of approximately seven surface collisions is required for the repulsive surfaces, decreasing to approximately two and a half for surfaces that are more attractive. The hops themselves are also influenced by long-range interactions, with increased electrostatic repulsion causing hops of longer duration and distance. These findings explicitly demonstrate that interfacial diffusion is dominated by biased 3D Brownian motion involving bulk-surface coupling and that it can be controlled by influencing short- and long-range adsorbate-surface interactions.

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“…[24,[39][40][41][42][43]. The results presented here provide a comprehensive picture of how and why adsorbate-surface interactions influence interfacial motion.…”

Section: Prl 119 268001 (2017) P H Y S I C a L R E V I E W L E T T Ementioning

confidence: 77%

“…However, the evidence for the presence of three-dimensional (3D) hops remains indirect, and critical aspects of the proposed "hopping" process remain a mystery. For example, theoretical models represent a flight as a series of hops (i.e., returns to the surface), where a molecule may stochastically readsorb after a given hop according to a hypothetical parameter known as the "sticking coefficient" [27]. While this parameter is theoretically the primary determinant of the flight length, to date there has been no actual support for the presence of multiple hops per flight.…”

mentioning

confidence: 99%

3D Imaging of Hopping Molecules

Barkai

¹

,

Garini

²

2017

Physics

0

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Theoretical predictions have suggested that molecular motion at interfaces-which influences processes including heterogeneous catalysis, (bio)chemical sensing, lubrication and adhesion, and nanomaterial self-assembly-may be dominated by hypothetical "hops" through the adjacent liquid phase, where a diffusing molecule readsorbs after a given hop according to a probabilistic "sticking coefficient." Here, we use three-dimensional (3D) single-molecule tracking to explicitly visualize this process for human serum albumin at solid-liquid interfaces that exert varying electrostatic interactions on the biomacromolecule. Following desorption from the interface, a molecule experiences multiple unproductive surface encounters before readsorption. An average of approximately seven surface collisions is required for the repulsive surfaces, decreasing to approximately two and a half for surfaces that are more attractive. The hops themselves are also influenced by long-range interactions, with increased electrostatic repulsion causing hops of longer duration and distance. These findings explicitly demonstrate that interfacial diffusion is dominated by biased 3D Brownian motion involving bulk-surface coupling and that it can be controlled by influencing short-and long-range adsorbate-surface interactions. DOI: 10.1103/PhysRevLett.119.268001 Molecular transport in fluid phases is understood in terms of the Brownian motion of individual molecules and particles, and can, therefore, be predicted and controlled by parameters including the hydrodynamic radius and fluid viscosity. In contrast, the analogous behavior at the interfaces remains poorly understood despite its fundamental interest and technological relevance; i.e., the dynamics of macromolecules at solid-liquid interfaces underlie many applications including chemical sensing, catalysis, lubrication, and adhesion [1][2][3][4][5][6]. While interfacial diffusion is nominally two dimensional (2D) and conventionally described in terms of 2D Brownian motion, longstanding theoretical models [7][8][9][10][11][12][13][14][15][16] have predicted that interfacial mass transport could actually be dominated by "flights" through an adjacent liquid phase, which would dramatically alter the nature of interfacial molecular motion; an understanding of this process is necessary in order to rationally control mass transport at surfaces. Recent experimental results indirectly support these predictions by measuring the 2D projection of trajectories for atoms, molecules, polymers, and nanoparticles, in thin films, at solid-liquid interface, and on lipid bilayers, which can be represented as an intermittent process with periods of apparent immobility alternating with long flights comprising a heavy-tailed distribution [17][18][19][20][21][22][23][24][25][26]. However, the evidence for the presence of three-dimensional (3D) hops remains indirect, and critical aspects of the proposed "hopping" process remain a mystery. For example, theoretical models represent a flight as a series of hops (i.e., ...

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“…The values of n are consistent with the effect of surface wettability. For a hydrophilic surface, the stronger liquid-solid affinity should result in a higher number of re-adsorption events as opposed to a hydrophobic surface [ 19 ]. In contrast, the surface hopping diffusion model greatly under-estimates the slip velocity, indicating that this mode of molecular motion is less likely to occur on the liquid-solid pair studied in the experiments.…”

Section: Discussionmentioning

confidence: 99%

Slip of fluid molecules on solid surfaces by surface diffusion

Shu

¹

,

Teo

²

,

Chan

³

2018

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The mechanism of fluid slip on a solid surface has been linked to surface diffusion, by which mobile adsorbed fluid molecules perform hops between adsorption sites. However, slip velocity arising from this surface hopping mechanism has been estimated to be significantly lower than that observed experimentally. In this paper, we propose a re-adsorption mechanism for fluid slip. Slip velocity predictions via this mechanism show the improved agreement with experimental measurements.

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Tuning the Flight Length of Molecules Diffusing on a Hydrophobic Surface

Cited by 13 publications

References 35 publications

Three-Dimensional Tracking of Interfacial Hopping Diffusion

Three-Dimensional Tracking of Interfacial Hopping Diffusion

3D Imaging of Hopping Molecules

Slip of fluid molecules on solid surfaces by surface diffusion

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