Self-Generated Diffusioosmotic Flows from Calcium Carbonate Micropumps

McDermott, Joseph J.; Kar, Abhijit; Daher, Majd; Klara, Steve; Wang, Gary; Sen, Ayusman; Velegol, Darrell

doi:10.1021/la303410w

Cited by 99 publications

(116 citation statements)

References 40 publications

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“…Due to the diffusioosmotic effect, concentration gradients around dissolving salt particles (7,8) can drive the radial motion of tracer particles at speeds of ∼10 μm/s, which is similar in order of magnitude to the flows observed from enzyme pumps (2). Notably, the motion of a particle due to solute concentration gradients near a wall is a combination of the diffusioosmotic fluid flow u DO along the fixed wall and diffusiophoretic motion of the particle relative to the fluid flow, v DP , both of which are proportional to the quantity ∇C=C, where C is the solute concentration (5,7). Near an impermeable Significance Surface-bound enzymes act as pumps in the presence of their specific substrates or promoters, thereby combining sensing and fluidic pumping into a single self-powered microdevice.…”

Section: Resultsmentioning

confidence: 99%

Convective flow reversal in self-powered enzyme micropumps

Ortiz-Rivera

Shum

Agrawal

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

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121

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Surface-bound enzymes can act as pumps that drive large-scale fluid flows in the presence of their substrates or promoters. Thus, enzymatic catalysis can be harnessed for "on demand" pumping in nano-and microfluidic devices powered by an intrinsic energy source. The mechanisms controlling the pumping have not, however, been completely elucidated. Herein, we combine theory and experiments to demonstrate a previously unreported spatiotemporal variation in pumping behavior in urease-based pumps and uncover the mechanisms behind these dynamics. We developed a theoretical model for the transduction of chemical energy into mechanical fluid flow in these systems, capturing buoyancy effects due to the solution containing nonuniform concentrations of substrate and product. We find that the qualitative features of the flow depend on the ratios of diffusivities δ = D P =D S and expansion coefficients β = β P =β S of the reaction substrate (S) and product (P). If δ > 1 and δ > β (or if δ < 1 and δ < β), an unexpected phenomenon arises: the flow direction reverses with time and distance from the pump. Our experimental results are in qualitative agreement with the model and show that both the speed and direction of fluid pumping (i) depend on the enzyme activity and coverage, (ii) vary with the distance from the pump, and (iii) evolve with time. These findings permit the rational design of enzymatic pumps that accurately control the direction and speed of fluid flow without external power sources, enabling effective, self-powered fluidic devices.enzyme micropumps | solutal convection | flow reversal | self-powered systems | catalysis N onmechanical nano/microscale pumps that provide precise control over fluid flow without an external power source and are capable of turning on in response to specific analytes in solution are needed for the next generation of smart micro-and nanoscale devices. Specific applications involve neutralization of toxins (1), on-demand drug or antidote delivery (2), and the directed focusing of targeted analytes for optimal sensing (3). Recent experiments have shown that surface-bound enzymes act as pumps in the presence of their specific substrates or promoters, driving large-scale fluid flows (2, 4). Furthermore, fluid velocity increases with increasing reaction rate. Therefore, enzymatic catalysis provides an intrinsic energy source for fluid movement and thus can be harnessed to overcome a significant obstacle in nano-and microfluidics: the need to use pressuredriven pumps to push fluids through devices. To fully exploit this behavior, it is vital to develop a fundamental understanding of how the chemical energy is transduced into mechanical fluid flow. One possible mechanism involves thermal buoyancy effects: An exothermic reaction catalyzed by the enzyme lowers the solution density, causing fluid to be drawn in and rise above the pump (Fig. 1A). Not all observed pumping, however, can be explained by this mechanism. In several instances (4), the thermal input from the enzymatic reaction is far lo...

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Section: Resultsmentioning

confidence: 99%

Convective flow reversal in self-powered enzyme micropumps

Ortiz-Rivera

Shum

Agrawal

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

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121

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“…Prieve (36) and coworkers noted an analogy with chemically reacting systems, e.g., as steel dissolution drives the diffusiophoretically accelerated deposition of latex particles. More recently, McDermott et al (65) showed that calcium carbonate particles dissolving in unsaturated aqueous solutions act as diffusioosmotic micropumps, driving flows along neighboring surfaces. Zheng and Pollack (66) reported long-range exclusion near hydrogel boundaries, and Florea et al (67) revealed ion exchange reactions to form a colloidal exclusion zone near membrane surfaces.…”

Section: Discussionmentioning

confidence: 99%

Soluto-inertial phenomena: Designing long-range, long-lasting, surface-specific interactions in suspensions

Banerjee

Williams

Azevedo

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

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Equilibrium interactions between particles in aqueous suspensions are limited to distances less than 1 μm. Here, we describe a versatile concept to design and engineer nonequilibrium interactions whose magnitude and direction depends on the surface chemistry of the suspended particles, and whose range may extend over hundreds of microns and last thousands of seconds. The mechanism described here relies on diffusiophoresis, in which suspended particles migrate in response to gradients in solution. Three ingredients are involved: a soluto-inertial "beacon" designed to emit a steady flux of solute over long time scales; suspended particles that migrate in response to the solute flux; and the solute itself, which mediates the interaction. We demonstrate soluto-inertial interactions that extend for nearly half a millimeter and last for tens of minutes, and which are attractive or repulsive, depending on the surface chemistry of the suspended particles. Experiments agree quantitatively with scaling arguments and numerical computations, confirming the basic phenomenon, revealing design strategies, and suggesting a broad set of new possibilities for the manipulation and control of suspended particles.olloidal suspensions and emulsions of 10-nm to 10-μm particles play a central role in a wide variety of industrial, technological, biological, and everyday processes. Everyday goods, including shampoos, inks, vaccines, paints, and foodstuffs as well as industrial products such as drilling muds, ceramics, and pesticides, rely fundamentally on stably suspended microparticles for their creation and/or operation. This incredible versatility derives from the extensive variety of properties (e.g., mechanical, optical, and chemical) attainable in suspension through a generic set of physicochemical strategies (1-4). A proper understanding of the stability and dynamics of suspensions in general thus underpins both fundamental science and technological applications.The properties and performance of suspensions depend preeminently on the effective interactions between particles. The celebrated Derjaguin-Landau-Verwey-Overbeek (DLVO) theory (5-7) balances electrostatic interactions (typically repulsive) between charged colloids-as screened by ions in the surrounding electrolyte-against van der Waals attractions, and successfully predicts the stability, phase behavior, and response of electrostatically stabilized suspensions. Additional (non-DLVO) forces can also be used to stabilize or destabilize colloidal suspensions. Grafted or adsorbed macromolecules provide short-range steric repulsions that stabilize suspended particles against van der Waals-induced flocculation (8-11). By contrast, nonadsorbed macromolecules that remain dispersed in solution introduce entropic depletion attractions whose strength and range is set by the size and concentration of depletants (12, 13). Such depletion interactions scale with thermal energy (k B T), and thus enable tunable and reversible attractions (14, 15). Clever design of shaped or patterned coll...

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“…16,70 The practical side of this field will continue to develop as new collective phenomena are discovered and their mechanisms are better understood. Self-propelled autonomous motors make their own decisions based on the local environment.…”

Section: Accounts Of Chemical Researchmentioning

confidence: 99%

From One to Many: Dynamic Assembly and Collective Behavior of Self-Propelled Colloidal Motors

et al. 2015

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S Supporting Information CONSPECTUS: The assembly of complex structures from simpler, individual units is a hallmark of biology. Examples include the pairing of DNA strands, the assembly of protein chains into quaternary structures, the formation of tissues and organs from cells, and the self-organization of bacterial colonies, flocks of birds, and human beings in cities. While the individual behaviors of biomolecules, bacteria, birds, and humans are governed by relatively simple rules, groups assembled from many individuals exhibit complex collective behaviors and functions that do not exist in the absence of the hierarchically organized structure. Self-assembly is a familiar concept to chemists who study the formation and properties of monolayers, crystals, and supramolecular structures. In chemical self-assembly, disorder evolves to order as the system approaches equilibrium. In contrast, living assemblies are typically characterized by two additional features: (1) the system constantly dissipates energy and is not at thermodynamic equilibrium; (2) the structure is dynamic and can transform or disassemble in response to stimuli or changing conditions. To distinguish them from equilibrium self-assembled structures, living (or nonliving) assemblies of objects with these characteristics are referred to as active matter. In this Account, we focus on the powered assembly and collective behavior of self-propelled colloids. These nano-and microparticles, also called nano-and micromotors or microswimmers, autonomously convert energy available in the environment (in the form of chemical, electromagnetic, acoustic, or thermal energy) into mechanical motion. Collections of these colloids are a form of synthetic active matter. Because of the analogy to living swimmers of similar size such as bacteria, the dynamic interactions and collective behavior of self-propelled colloids are interesting in the context of understanding biological active matter and in the development of new applications. The progression from individual particle motion to pairwise interactions, and then to multiparticle behavior, can be studied systematically with colloidal particles. Colloidal particles are also amenable to designs (in terms of materials, shapes, and sizes) that are not readily available in, for example, microbial systems. We review here our efforts and those of other groups in studying these fundamental interactions and the collective behavior that emerges from them. Although this field is still very new, there are already unique and interesting applications in analysis, diagnostics, separations, and materials science that derive from our understanding of how powered colloids interact and assemble.

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Self-Generated Diffusioosmotic Flows from Calcium Carbonate Micropumps

Cited by 99 publications

References 40 publications

Convective flow reversal in self-powered enzyme micropumps

Convective flow reversal in self-powered enzyme micropumps

Soluto-inertial phenomena: Designing long-range, long-lasting, surface-specific interactions in suspensions

From One to Many: Dynamic Assembly and Collective Behavior of Self-Propelled Colloidal Motors

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