Continuous-Flow Biomolecule and Cell Concentrator by Ion Concentration Polarization

Abstract

We present a novel continuous-flow nanofluidic biomolecule/cell concentrator, utilizing the ion concentration polarization (ICP) phenomenon. The device has one main microchannel which bifurcates into two channels, one for a narrow, concentrated stream and the other for a wider but target-free stream. A nanojunction [cation-selective material (Nafion)] is patterned along the tilted concentrated channel. Application of an electric field generates the ICP zone near the nanojunction so that biomolecules and cells are guided into the narrow, concentrated channel by hydrodynamic force. Once biomolecules from the main channel are continuously streamed out to the concentrated channel, one can achieve a continuous flow of the same sample solution but with higher concentrations up to 100-fold. By controlling hydrodynamic resistance of the main and concentrated channel, the concentration factors can be adjusted. We demonstrated the continuous-flow concentration with various targets, such as bacteria [fluorescein sodium salt, recombinant green fluorescence protein (rGFP), red blood cells (RBCs), and Escherichia coli ( E. coli )]. Specially, fluorescein isothiocyanate (FITC)-conjugated lectin from Lens culinaris (lentil) (FITC-lectin) was tested on the different buffer conditions to clarify the effect of polarities of the target sample. This system is ideally suited for a generic concentration front-end for a wide variety of biosensors, with minimal integration-related complications.

Capillarity ion concentration polarization for spontaneous biomolecular preconcentration mechanism

“…The ability to control ion transport through a nanoporous membrane or nanochannel via an external electric field has been utilized for significant engineering applications, such as electrodesalination, [1][2][3][4] concentrating biomolecules, 5-9 separation, 10,11 fluid pumping and switching, 12 nanofluidic diodes, and ionic field effect transistors. [13][14][15][16][17] Elucidating the fundamentals of ion transportation also remains an active research area because various related phenomena are not fully understood yet.…”

Folding-paper-based preconcentrator for low dispersion of preconcentration plug

“…Although many studies investigated analytical systems for both analytical and point-of-care (POC) applications [14][15][16], detecting biomolecules at concentrations below the limit of detection (LOD) is still a critical issue for analytical devices. To address this problem, an ICP-based preconcentrator has been developed [17,18] for enhancing the LOD.…”

Continuous sheathless microparticle and cell patterning using CL-SSAWs (conductive liquid-based standing surface acoustic waves)

“…32 However, the introduction of sheath flow complicates a microfluidic device, wastes large volume of buffer solution and dilutes the sample concentration. 33,34 Moreover, there is still room for further researches on particle/cell manipulation in a chamber and a channel due to serpentine-shaped electrode channels which differ from conventional metal electrode patterns. Here, we introduce a CL-based standing SAW (CL-SSAW) microfluidic device for the sheathless patterning of microparticles and continuous concentration of malaria parasites as a preliminary study.…”

“…36,37 Therefore, the development of continuous concentration techniques for rare cells have still been required. 34,38,39 The proposed method can overcome the abovementioned limitations of the fabrication procedure for the conventional SSAW device and can be further applied to sample pre-treatment. Figure 1 shows the fabrication process for the CL-SSAW patterning device.…”