Periodic concentration–polarization-based formation of a biomolecule preconcentrate for enhanced biosensing

Abstract

Ionic concentration-polarization (CP)-based biomolecule preconcentration is an established method for enhancing the detection sensitivity of target biomolecules. However, the formed preconcentrated biomolecule plug rapidly sweeps over the surface-immobilized antibodies, resulting...

Preconcentration of Fluorescent Dyes in Electromembrane Systems via Electrophoretic Migration

“…However, to simplify the nanochannel fabrication via lithography and maximize the ICP phenomenon, microfluidic preconcentrators have been developed using ion-selective polymers (e.g., Nafion) [ 15 ]. This allows for a wide range of experimental studies for evaluating various conditions and samples to be performed with minimal device fabrication requirements and considerably enhanced preconcentration efficiency [ 16 , 17 , 18 , 19 , 20 , 21 , 22 ]. However, although the preconcentration efficiency is high for such static ICP preconcentrators, difficulties involved in extracting target samples collected at the preconcentration plug without loss significantly limit the practical application of this technology.…”

Microvalve-Based Tunability of Electrically Driven Ion Transport through a Microfluidic System with an Ion-Exchange Membrane

“…ICP-driven preconcentration is commonly realized within microfluidic channels with relatively high hydraulic permeability, either by employing the ionic permselective medium as a bridge between two microchannels ,− or as a patterned thin surface coating embedded at the bottom of the main microchannel. ,− The latter can be also realized using an electrode instead of an ionic permselective medium wherein the local ion concentration is modulated via electrochemical reaction (often termed faradic ICP). , These microfluidic system designs maintain minimal hydrodynamic interference within the microfluidic channels and support a sufficiently high flow rate and flux of target bioparticles toward the plug. However, for robust preconcentration, aside from the requirement for high throughput to achieve rapid bioparticle accumulation, precise overlap of the plug with the sensing region (e.g., immobilized molecular probes as antibodies , or electrodes for electrochemical sensing) is essential. One way of achieving such an overlap is via extensive precalibration involving an elaborate process of trial and error to define the optimal operation conditions (e.g., applied voltage and flow rate) as a function of the system parameters (e.g., ionic strength, geometry, and target molecules).…”

“…This ion depletion results in a strong electric field gradient, which traps and preconcentrates charged bioparticles into a plug through a mechanism known as field gradient focusing. , The trapping occurs due to a force balance between the counter-acting advection and electro-migration at the edge of the depletion layer. The concentration of the target bioparticle (e.g., DNA, , protein, , and bacteria , ) at the plug can reach several orders of magnitude of the initial concentration, which significantly enhances its detection. Among other electrokinetic-based bioparticle preconcentration techniques, e.g., dielectrophoresis , and isotachophoresis , molecular trapping, ICP-driven preconcentration is regarded as one of the most efficient and common tools for enhancing the detection of charged bioparticles in microscale bioanalysis .…”

Predicting ion concentration polarization and analyte stacking/focusing at nanofluidic interfaces

“…Simulations in simple channels were also developed by Dubsky et al [17] to investigate ICP of DNA molecules as a plug of immobilized anions. In addition to numerical studies, many microfluidic-based methods have been used for preconcentration of analytes on-chip, such as ion concentration polarization focusing (ICPF) [18][19][20], ICP-based electrokinetic molecular concentration (EMC) [21] and periodic ICP [22]. This paper is organized as follows.…”

“…In addition to numerical studies, many microfluidicbased methods have been used for preconcentration of analytes on-chip such as ICP focusing [18][19][20] and periodic ICP [21]. A common fluidic architecture encountered in ICP-based preconcentration devices is one with a continuous microchannel and orthogonally oriented nanochannels branching away from the microchannel, wherein one applied field drives transport through the microchannel and another induces ICP across the nanochannels to form an extended depletion zone in the continuous microchannel [1,2,4,11,15,16,19,22].…”