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Method and apparatus for precise selection and extraction of a focused component in isoelectric focusing performed in micro-channels

a microchannel and focused component technology, applied in the field of methods and equipment, can solve the problems of unavoidable component zone broadening, cross-contamination of closely migrating peaks, and inability to achieve more conventional separatory methods

Inactive Publication Date: 2008-02-14
PROTEINSIMPLE
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[0020] According to a preferred embodiment of apparatus according to to the invention there is provided a coplanar, cross-channel microfluidic device comprising a sample mixture introduction and separation channel and an extraction channel in fluid communication at a point of intersection; means of producing a pattern of amphoteric components separated into focused, stationary zones within the separation channel; an apparatus for irradiating the whole separation channel with ultraviolet (UV) light and having a detector that can provide UV absorption imaging detection of the whole separation channel providing real-time or at least very, rapid digital images of the cIEF separation process; means of selecting a specific focused, component zone or peak in the separation channel and moving the said peak to the intersection of the separation and extraction channels; the aforementioned whole-channel, real-time imaging detection apparatus to monitor the movement of the selected component peak and to visualize the alignment of said peak to the intersection of the separation and extraction channels; and means for moving the aligned, component peak or a portion of the peak into and then out of the extraction channel for collection or interface to a second analytical apparatus such as a mass spectrometer.

Problems solved by technology

This is generally not possible with more conventional separatory methods, even high-performance liquid chromatography (HPLC).
Cross-contamination frequently occurs for closely migrating peaks due to the extremely narrow peak width and extremely small amount of eluant.
Even then, however, component zone broadening is unavoidable during the separation process for the reasons stated above.
To date, however, others have had limited success in achieving any high degree of precision in the selection and extraction of cIEF component zones, chiefly because of the following limitations to the operation of their devices: 1) mobilization flow is in one direction; 2) mobilization speed is pre-determined and generally fixed and 3) inability to visualize the entire separation zones and detect in real-time any zone-width distortion due to mobilization.
This mobilization step in cIEF requires extra time and distorts the focused peaks, making it difficult to collect pure peaks without cross-contamination when peaks focus in close proximity.
It has, accordingly, not been possible with existing microfluidic (capillary) electrophoretic devices for micro-preparative fraction collection to observe all of the separated peaks developed by electrophoresis, then select a particular peak of interest and mobilize the entire pattern of peaks, while maintaining or re-establishing the focus of the pattern to bring the selected peak to a separation / collection point.

Method used

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  • Method and apparatus for precise selection and extraction of a focused component in isoelectric focusing performed in micro-channels

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experimental examples

Example 1

[0058] An IMED having the structure shown in FIG. 3 was used to selectively extract different hemoglobin variants of a mixture. An imaged cIEF system (Model iCE280, Convergent Bioscience Ltd., Toronto, Canada) was used as the real-time, whole separation channel UV detection apparatus, and protein detection was achieved through UV absorption at 280 nm. An autosampler from Prince CE system (Prince. Technologies, Emmen, The Netherlands) was used for sample injection and fluid manipulation along the separation channel. Methyl cellulose (MC), hourse heart myoblobin, human transferrin, and pH 3-10 Pharmalyte were obtained from Sigma (St Louse, Mo.). Hemoglobin control AFSC was obtained from Helena Laboratories (Beaumont, Tex.). HPLC grade water was from J. T. Baker (Phillipsburg, N.J.), and was used for all solutions. Sample mixture solution was prepared by mixing protein with 8% pH 3-10 Pharmalytes and 0.35% MC.

[0059] The extraction channel of the IMED was first filled with HP...

example 2

[0063]FIG. 5 shows the separation and extraction of Hemoglobin S in the IMED with the device according to FIG. 4. The pI difference between Hemoglobin F and S and between Hemoglobin S and C was about 0.1. It can be seen that the separation pattern was not affected significantly upon hemoglobin s extraction, while the peak area of Hemoglobin S was reduced following extraction.

example 3

[0064] An IMED having the structure substantially represented in FIG. 2 was used to separate and selectively extract target protein component for off line MALDI-TOF characterization. FIG. 6 shows the cIEF electrophoregram of myoglobin and transferrine in 8% 5-8 Pharmalytes, 0.35% MC solution. It can be seen that the major component of transferrine and the major component of myoglobin were very well separated. Upon cIEF separation, the extracted individual protein was diluted to 100 μL in DI water, and 1 μL of this diluted sample was further diluted at either 1:2 or 1:10 ratio with 0.2% (v / v) trifluoroacetic acid in water. The further diluted protein sample of 1 μL was mixed with 1 μL of sinapinic acid (10 mg / mL), and 1 μL of this sample mixture was spotted for MALDI TOF MS (Voyager STR, Applied Biosystems, Foster City, Calif.).

[0065]FIGS. 7 and 8 shows the mass spectrograms of extracted myoglobin and transferrine. From the mass spectrogram, it can be seen that the presence of carri...

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Abstract

An apparatus and method are disclosed for the precise selection and extraction of a selected analyte in a focused zone produced by isoelectric focusing performed in micro-channels. A cross-channel microfluidic device comprises a sample mixture introduction and separation channel and an extraction channel, which are in fluid communication with each other at a point of intersection. Means are provided for selectively moving the pattern of separated zones following cIEF to the intersection point, and means are provided for applying an extraction pressure to direct a single zone containing a selected analyte into and then out of the extraction channel for collection.

Description

CROSS REFERENCE TO RELATED APPLICATIONS [0001] This application claims the benefit under 35 U.S.C. § 119(e) of U.S. Provisional Patent Application No. 60 / 819,390, filed on Jul. 10, 2006, the disclosure of which is incorporated by reference herein.STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT [0002] N / A FIELD OF THE INVENTION [0003] This invention relates to the separation and precise selection and extraction of components of an analyte mixture by means of liquid-phase capillary or micro-channel electrophoresis. The principal application of the invention is to facilitate the identification and characterization of the extracted component(s) through the subsequent use of micro-analytical techniques such as mass spectrometry. BACKGROUND OF THE INVENTION [0004] Capillary electrophoresis (CE) has been established as an important separation technique in bioanalytical chemistry. Separation and detection of very small amounts of biological samples, about pL-nL volumes, can ...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): B01D57/02B01J19/08
CPCB01L3/5027G01N1/40G01N27/44739G01N2001/4038G01N27/44795
Inventor WU, JIAQIHUANG, TIEMINWATSON, ARTHUR H.
Owner PROTEINSIMPLE
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