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Proteomics is the investigation of all the proteins (a vast majority of drug targets) present in a cell, tissue or organism. We are helping the life science industry in providing Micro/nanofluidic-driven solutions to facilitate improved separation and increased pre-concentration of samples even from single cells. Examples of CFDRC’s work are provided below:
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Schematic of 2D chip separation device. A: Anolyte, C: Catholyte, B1 and B2: Buffer and W1 and W2: Waste |
CE-ITP based 2D separation device (with Los Alamos National Laboratory):
In collaboration with Bioscience Division at Los Alamos National Laboratory (Dr. Jose Olivares), we developed simulation tools to study a 2-D microchip based separation system that employs capillary isoelectric focusing (CIEF) coupled with capillary zone electrophoresis (CZE) and uses a real-time fluorescent imaging of the analytes as they are separated. Physics-based simulations have been developed to understand the fundamental physico-chemical processes occurring in this system. Various parameters that affect the design of the chip, instrument and detection system were studied and optimal separation conditions investigated.
Field Amplified Sample Stacking System
In collaboration with Stanford University, we have developed sample stacking in an electrokinetic system. In this system, two buffers with differing electrical conductivity are kept side by side and the sample (containing the biomarker of interest) is flowed in. On the application of external potential, discontinuous electric field sets up in order to conserve current. This causes differential migration of the sample, leading to piling (stacking), resulting in highly concentrated plug of the sample. A thin band of highly concentrated sample (10-100X has been reported) can be achieved.
Nanoelectrophoresis
To illustrate application in nano-electrophoresis, we investigated separation of neutral and negatively charged analytes injected into a nanochannel of 300nm. Figure shows the
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t=0 (Negatively Charged Species)
t=0 (Neutral Species)
t=0.1 (Negatively Charged Species)
t=0.1 (Neutral Species)
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(a) contours of electric potential and line-plot of electroosmotic velocity and potential along the axis. (b) Separation of charged species from a neutral species. |
prototype device comprising of a nano channel array that connects two microchannel reservoirs. The z potential is –50mV and the Debye thickness is ~50nm. The axial flow is driven by an external electric field. The results are summarized in the right hand side of the Figure. The EOF velocity and the overlapping of EDL are shown. A single channel is simulated for demonstration purpose only. A small amount of charged and neutral species of 0.1mM concentration is pushed into the nanochannel. Because of electrostatic exclusion, the charged specie is concentrated at the mid of the channel where EOF velocity is higher and analyte band moves faster. The concentration field of species is shown for t=0s and 0.1s and the separation is observed within a short period of time. This demonstrates that our simulation-based design and analysis can be applied to study quantitatively a variety of electrokinetic and species transport problems in nanochannels. From the simulation, the conventional electrophoresis of charged analytes is much smaller compared to EOF separation and thus is neglected in the present study.
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