Convective flow reversal in self-powered enzyme micropumps
| Autor: | Henry Shum, Ayusman Sen, Isamar Ortiz-Rivera, Arjun Agrawal, Anna C. Balazs |
|---|---|
| Jazyk: | angličtina |
| Rok vydání: | 2016 |
| Předmět: |
Buoyancy
Materials science Surface Properties Microfluidics 02 engineering and technology engineering.material 010402 general chemistry Convection 01 natural sciences Nano Fluid dynamics Fluidics Computer Simulation Simulation Multidisciplinary Microfluidic Analytical Techniques Models Theoretical 021001 nanoscience & nanotechnology Enzymes Immobilized Urease 0104 chemical sciences Transduction (biophysics) Chemical energy Kinetics Chemical physics Physical Sciences engineering 0210 nano-technology Energy source Algorithms |
| Popis: | 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. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|