scholarly journals Glucose Oxidase Micropumps: Multi-Faceted Effects of Chemical Activity on Tracer Particles Near the Solid–Liquid Interface

2019 ◽  
Vol 4 (3) ◽  
pp. 73 ◽  
Author(s):  
Raluca-Elena Munteanu ◽  
Mihail N. Popescu ◽  
Szilveszter Gáspár
Keyword(s):  
Glucose Oxidase ◽  
Areal Density ◽  
Plane Motion ◽  
Plane Region ◽  
Depletion Zone ◽  
Rate Dependent ◽  
Tracer Particles ◽  
Lateral Extent ◽  
Solid Liquid Interface ◽  
Solid Liquid

We report the development of glucose oxidase pumps characterized by small lateral dimensions (≈200 μ m). We studied the effects of the activity of the enzyme pump on silica particles (“tracers”) sedimented around the enzyme pump/patch. Once the activity of the pump was turned on (i.e., the glucose substrate was added to the solution), in-plane motion of the tracers away from the enzyme patch, as well as the emergence of an in-plane region around the patch which was depleted by tracers, was observed. The lateral extent of this depletion zone increased in time at a rate dependent both on the glucose concentration and on the areal density of the enzyme in the patch. We argue that, when the tracers were very near the wall, their motion and the emergence of the depletion zone were most likely the result of diffusiophoresis and drag by osmotic flows induced at the wall, rather than that of drag by a solutal buoyancy driven convective flow. We infer that, for the glucose oxidase enzymatic pumps, bulk (solutal buoyancy), as previously reported, as well as surface (osmotic) driven flows coexist and have to be explicitly accounted for. It seems plausible to assume that this is the case in general for enzyme pumps, and these complementary effects should be considered in the design of applications, e.g., stirring or sensing inside microfluidic systems, based on such pumps.

FINITE ELEMENT SIMULATION OF BIOFILM VISCOELASTIC BEHAVIOR UNDER VARIOUS LOADINGS

2018 ◽  
Vol 18 (05) ◽  
pp. 1850056 ◽  
Author(s):  
XIAOLING WANG ◽  
KAI ZHAO ◽  
HUI ZHAO
Keyword(s):  
Finite Element ◽  
Viscoelastic Model ◽  
Viscoelastic Behavior ◽  
Maxwell Model ◽  
Theoretical Models ◽  
Rate Dependent ◽  
Air Interface ◽  
Linear Viscoelastic Theory ◽  
Solid Liquid Interface ◽  
Solid Liquid

Experiments showed that biofilms exhibit viscoelasticity under both displacement and stress loadings, irrespective of pellicles at liquid–air interface or biofilms at solid–liquid interface. However, the general theoretical models are lacking inuniformly and quantitatively describing biofilms’ viscoelastic behavior under various loading conditions. We use the linear viscoelastic theory — Generalized Maxwell model to describe the viscoelastic mechanical properties of biofilms, and study the responses of biofilms under different loadings, including various strain/stress loading rates and cyclic loadings, by finite element method. The results can capture the typical viscoelastic characteristics of biofilms, such as creep, hysteresis, energy dissipation and loading rate-dependent behavior. Our work provides a simple viscoelastic model not only for bacterial biofilms but also for other biological materials.

scholarly journals The impact of geometrical confinement in a slab on the behavior of tracer particles near active glucose oxidase micropump

2020 ◽  
Author(s):  
Raluca-Elena Munteanu ◽  
Mihail N. Popescu ◽  
Szilveszter Gáspár
Keyword(s):  
Glucose Oxidase ◽  
Glucose Solution ◽  
Microfluidic Devices ◽  
Depletion Zone ◽  
Promising Direction ◽  
Tracer Particles ◽  
Catalytically Active ◽  
Self Powered ◽  
Low Ionic Strength ◽  
The Impact

Abstract Patches of surface-immobilized and catalytically active enzyme, immersed into a solution with the corresponding substrate, induce flow in the solution. Such systems are currently investigated as a promising direction in the development of self-powered micropumps that could operate autonomously within microfluidic devices. Here, we investigate the influence of confinement, within a slab of height H, on the response exhibited by silica tracer particles sedimented near a chemically active glucose oxidase patch which is immersed into a glucose solution of very low ionic strength. Irrespective of the value H, within the range explored in this study, a region depleted of tracers forms around the patch. When H is not much larger than the radius of the patch, the rate of growth of the depletion zone depends on H; somewhat surprisingly, this dependence is influenced by the glucose concentration. The results are discussed within the context of a simple model for a chemically active patch.

Atom-probe analysis of the solid-liquid interface

1995 ◽  
Vol 53 ◽  
pp. 676-677
Author(s):  
J.A. Panitz
Keyword(s):  
Molecular Level ◽  
Selective Adsorption ◽  
Electronic Devices ◽  
Atom Probe ◽  
Chemical Agent ◽  
Hostile Environment ◽  
Solid Interface ◽  
Solid Liquid Interface ◽  
Solid Liquid ◽  
Chemically Selective

The first few atomic layers of a solid can form a barrier between its interior and an often hostile environment. Although adsorption at the vacuum-solid interface has been studied in great detail, little is known about adsorption at the liquid-solid interface. Adsorption at a liquid-solid interface is of intrinsic interest, and is of technological importance because it provides a way to coat a surface with monolayer or multilayer structures. A pinhole free monolayer (with a reasonable dielectric constant) could lead to the development of nanoscale capacitors with unique characteristics and lithographic resists that surpass the resolution of their conventional counterparts. Chemically selective adsorption is of particular interest because it can be used to passivate a surface from external modification or change the wear and the lubrication properties of a surface to reflect new and useful properties. Immunochemical adsorption could be used to fabricate novel molecular electronic devices or to construct small, “smart”, unobtrusive sensors with the potential to detect a wide variety of preselected species at the molecular level. These might include a particular carcinogen in the environment, a specific type of explosive, a chemical agent, a virus, or even a tumor in the human body.

The role of (bio)surfactant sorption in promoting the bioavailability of nutrients localized at the solid-water interface

1999 ◽  
Vol 39 (7) ◽  
pp. 91-98 ◽  
Author(s):  
Ryan N. Jordan ◽  
Eric P. Nichols ◽  
Alfred B. Cunningham
Keyword(s):  
Mass Transfer ◽  
Cell Membrane ◽  
Substrate Concentration ◽  
Water Interface ◽  
Industrial Systems ◽  
Solid Liquid Interface ◽  
Solid Liquid ◽  
Surfactant Sorption

Bioavailability is herein defined as the accessibility of a substrate by a microorganism. Further, bioavailability is governed by (1) the substrate concentration that the cell membrane “sees,” (i.e., the “directly bioavailable” pool) as well as (2) the rate of mass transfer from potentially bioavailable (e.g., nonaqueous) phases to the directly bioavailable (e.g., aqueous) phase. Mechanisms by which sorbed (bio)surfactants influence these two processes are discussed. We propose the hypothesis that the sorption of (bio)surfactants at the solid-liquid interface is partially responsible for the increased bioavailability of surface-bound nutrients, and offer this as a basis for suggesting the development of engineered in-situ bioremediation technologies that take advantage of low (bio)surfactant concentrations. In addition, other industrial systems where bioavailability phenomena should be considered are addressed.

Observation of Femtosecond Acoustic Anomaly in a Solid Liquid Interface

2020 ◽  
Vol 124 (5) ◽  
pp. 2987-2993
Author(s):  
Chi-Kuang Sun ◽  
Yi-Ting Yao ◽  
Chih-Chiang Shen ◽  
Mu-Han Ho ◽  
Tien-Chang Lu ◽  
...  
Keyword(s):  
Liquid Interface ◽  
Acoustic Anomaly ◽  
Solid Liquid Interface ◽  
Solid Liquid
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