US20070017870A1 - Multicapillary device for sample preparation - Google Patents

Abstract

A multicapillary sample preparation device, especially useful for handling biological samples, comprising a plurality of uniform capillary tubes coated with a stationary phase, and arranged in a monolithic element. The multicapillary device is suitable for attachment to a pipette, micropipette, syringe, or other analytical or sample preparation instrument.

Description

REFERENCE TO RELATED APPLICATIONS
• This application claims benefit of U.S. patent application No. 10/955,377 filed Sep. 30, 2004, and U.S. Provisional Patent Application No. 60/507,474 filed Sep. 30, 2003.
BACKGROUND OF THE INVENTION
• 1. Field of the Invention
• The present invention relates to a multicapillary sample preparation device especially useful for handling biological samples. In particular, the multicapillary device is suitable for use with a pipette, micropipette, syringe, or other similar analytical instrument.
• 2. Background Art
• Many biological samples are commonly separated by gel electrophoresis and analyzed by matrix assisted laser desorption/ionization mass spectrometry (MALDI-MS). One disadvantage of these techniques, however, is that analysis is strongly affected by the presence of salts, buffers and low molecular weight organic compounds commonly used in the preparation of biological samples. In order to improve the sensitivity and selectivity of analyses, adsorptive and membranous devices are frequently used to purify and concentrate the sample prior to analysis. Such devices feature a bed of porous adsorbent or a semipermeable membrane fixed in a housing of a suitable dimension and shape that traps desired constituents, while allowing contaminants to pass.
• To handle samples in the 0.01 to 100 microgram (μg) range, pipettes, micropipettes, syringes or similar analytical instruments (collectively referred to hereinafter as “pipettes”) are commonly employed. The tip of these pipettes is fitted with one or more adsorptive or membranous plugs capable of purifying, concentrating, or fractionating peptides and other biomolecules.
• A principal shortcoming of adsorptive and membranous plugs, however, is that porous materials are generally not effective at separating smaller biomolecules such as proteins and polynucleotides. Porous plugs are also deficient with respect to isolating and purifying larger biological materials and nucleic acids such as DNA, RNA and cells. This shortcoming derives from the fact that during sample processing, molecules must wend through a labyrinth of sponge-like, expansive and porous adsorbent silica.
• There is little uniformity, consistency, and reproducibility of porous materials used for sample preparation. Sample loss in existing pipette tips is typically about 40-60%. Poor sample recovery is largely due to the fact that a sample must travel through irregular voids in the porous material, whereby a portion of the sample lodges in small voids and is unrecoverable. Moreover, in order to achieve adequate results, samples must be passed through porous materials multiple times (e.g., ten). The sample preparation devices are usually not reusable and fit poorly with automatic instrumentation because poor sample recovery may give rise to contamination due to sample carry-over.
• Spin columns and other apparatus operated by a centrifuge rotor are commonly used for the isolation and purification of biological and nucleic acid samples. However, it is desirable in certain applications to avoid the use of a centrifuge for rotating a specimen to be isolated and purified. This is due, in part, to the fact that horizontal separation may result in centrifugal forces of up to, for example, 4,000 RPM, being exerted on or transmitted along the vertical axis of the spin column and sample in order to achieve satisfactory separation. Air resistance negatively affects the spin column by generating drag and friction, which heat the spin column and its contents. Considerable breakage of sample fragments is unavoidable due to the heat transfer, acute centrifugal force and accompanying air resistance. The impaired quality of biological and nucleic acid samples extracted during spin column and centrifugal processing is highly undesirable to the user.
• It can be seen, therefore, that the purification and concentration of biological and nucleic acid samples using porous materials prior to instrumental analysis is time consuming, is poorly reproducible, has low throughput, and requires repeated passing of a sample through the porous plug.
• Accordingly, it is an object of the present invention to provide an efficient sample preparation device for use in isolating (immunoassay), purifying and concentrating samples of proteins, peptides, nucleic acids (e.g., DNA and RNA), and other biological materials (e.g., cells) prior to analysis.
• It is also an object of the invention to provide a sample preparation device with high sample capacity that increases throughput and reduces sample loss.
• It is a further object of the invention to provide a highly reproducible sample preparation device that achieves uniformity, consistency, and nearly identical pathways for sample passage.
• It is a still further object of the invention to provide a sample preparation device that is simple, cost-effective, and does not require the use of a silica type porous substrate or special equipment such as a centrifuge.
SUMMARY OF THE INVENTION
• The invention is a high surface area multicapillary sample preparation device especially useful for handling biological samples. The multicapillary device does not require use of a silica type porous substrate. Rather, the device incorporates a plurality of parallel capillary tubes, wherein the cavity of each tube remains open and unobstructed throughout sample processing. The capillary tubes of the device function independently of one another so that sample molecules are incapable of being physically exchanged or diffusing from one capillary to another. The multicapillary device is preferably disposed in a housing that is suitable for attachment to a “pipette” or other sample preparation or analytical instrument, enabling the isolation, purification, concentration and/or fractionation of nucleic acids or biological samples in the micro- and nanoliter range, as well as larger mass loads and volumes. In an embodiment of the invention, the multicapillary device features a monolithic element pierced with multiple uniform capillaries. The monolithic element is typically mounted in the lower end of a pipette tip, syringe needle or tubing, and is operated using a pipette.
• For protein separation and purification applications, an insoluble stationary phase material is deposited onto the interior surfaces (walls) of each capillary tube, without employing a supporting or intermediary constituent.
• The invention also includes a method of preparing a multicapillary device for protein sample preparation. In such method, inner walls of the capillary tubes are first coated with a stationary phase material, and then the monolithic element is mounted in an appropriate housing. Alternatively, the monolithic element can first be fixed in a housing, after which the capillary walls can be coated with the stationary phase. For operation, the multicapillary sample preparation device is attached to a pipette, micropipette, tube, syringe or similar analytical instrument.
BRIEF DESCRIPTION OF THE DRAWINGS
• FIG. 1 is a perspective view of a multicapillary device for sample preparation in accordance with an embodiment of the present invention. Individual capillaries of the device are shown in the enlarged, cross-sectional views ofFIGS. 2A, 2C and2D (SEM).FIG. 2B is an exploded, perspective view of an individual capillary tube.
• FIG. 3 depicts SEM images showing cross-sectional views of a conventional sample preparation device.
• FIGS. 4A-4D are perspective views of pipette tips and a pipette format multicapillary device, respectively, in accordance with the present invention.
• FIGS. 5A-5C show perspective views of a syringe format multicapillary device for sample preparation according to the present invention.
• FIG. 6 is a chromatogram showing the separation of a three component mixture in a multicapillary device for sample preparation according to the present invention.
• FIG. 7A is a chromatogram illustrating the performance of a multicapillary sample preparation device in sample enrichment as compared to a standard SPE cartridge,FIG. 7B.
• FIGS. 8A and 8B are mass spectra demonstrating the performance of a multicapillary sample preparation device in desalting of complex peptide mixtures.
• FIGS. 9A and 9B are mass spectra demonstrating the performance of a multicapillary sample preparation device in fractionating of complex peptide mixtures.
• FIG. 10 shows gels demonstrating sample capacity and recovery performance (10A), reproducibility (10B), and time performance (10C) of a conventional device versus a multicapillary sample preparation device according to the present invention. Comparative data is shown in Table 2.
• FIG. 11A is a perspective view of a conventional spin column used for DNA purification.FIGS. 11B and 11C are SEM images of the spin column.
• FIGS. 12A and 12B, respectively, show pulsed field and agarose gel electrophoresis analyses performed to determine DNA quality and size of a conventional spin column versus a multicapillary sample preparation device according to the present invention.
• FIGS. 13A and 13B, respectively, show sample purification results of conventional spin columns versus a multicapillary sample preparation device of the present invention in terms of DNA yield and time required for sample preparation
DETAILED DESCRIPTION OF THE INVENTION
• In accordance with the present invention, a parallel capillary array or multicapillarysample preparation device12 is provided for use with commercially available pipettes to permit the isolation, purification, concentration and/or fractionation of biological samples in the micro- and nanoliter range, as well as larger mass loads and volumes. The invention includes both detachable and integrally embeddedmulticapillary devices12 adapted for use with manual and automatic pipettes,micropipettes20,syringes22 and other sample handling or analytical instruments. Notably, themulticapillary device12 does not require use of a silica type porous substrate.
• Referring now toFIGS. 1 and 2, there is shown a multicapillary device forsample preparation12 comprising a monolithic element (rod, tube, etc.)14 that has an upper end and a lower end, and defines a chamber.Capillary tubes16 of uniform internal diameter and length are arranged within the chamber. Eachcapillary tube16 includes a non-porous or imperforate wall having an inner and an outer surface, which defines an inner bore. Eachtube16 also includes a first and a second opening at opposing ends, so that resistance and backpressure are low.
• For protein or peptide separation and purification applications, it is preferable to deposit an insolublestationary phase18 on imperforate inner walls of thecapillary tubes16. For the separation and purification of polar compounds such as nucleic acids (e.g., DNA and RNA), it is preferable that the insolublestationary phase18 comprise a polar material. In a preferred embodiment of the invention, the thickness of thestationary phase18 is correlated with the radius of individualcapillary tubes16 to optimize efficiency of themulticapillary device12. As a result, during application of thestationary phase18, a greater amount settles on the inner surface of wider capillaries; while a smaller amount settles on the inner surface of narrower capillaries. Through this process, thecapillaries16 achieve quasi-uniformity, which substantially increases the efficiency of themulticapillary device12. The following relationship for high peak efficiency has been derived by the inventors:
  d_f(r)=c_r·rⁿ  (Equation 1)
• The stationary phase film thickness d_fis proportional to capillary radius r in power n, where n>1; c_fis a constant.
• In a more preferred embodiment, the thickness of thestationary phase coating18 is proportional to the radius of thecapillary tubes16 in power n, where n is greater than 1.
• To achieve the highest peak efficiency, the stationary phase thickness d_fis proportional to capillary radius r inpower3.
• Stationary phase media18 is retained on the interior surfaces of the imperforate,hollow capillary tubes16 via stable chemical bonding or cross-linking. There is, therefore, no discharge ofstationary phase media18 into the mobile phase during separation, reducing sample contamination. In the open tubular system of themulticapillary device12, supporting intermediary constituents and adsorptive and membranous plugs (e.g., porous adsorbent silica particles or fibers) are unnecessary. The lumen or inner cavity of eachcapillary tube16 remains unobstructed and impediment free throughout the protein, peptide, nucleic acid or biological sample separation process. In this stable, surface-mediated mechanism of separation, sample molecules are incapable of diffusing between and through the imperforate walls of thecapillary tubes16 or from one capillary to another.Individual capillary tubes16 remain physically and functionally independent of one another.
• The multicapillary device forsample preparation12 may be detachably mounted (mechanically) or fixedly inserted (e.g., by melting or adhesion) about the end portion of a pipette tip, needle, tubing or other housing of suitable shape and dimension that is attachable to apipette20. Themulticapillary device12 receives a sample in a mobile (liquid) phase at its first end, and a concentrated and purified sample, devoid of contaminants such as salts and buffers, is discharged at a second end of thedevice12.
• As shown inFIGS. 2A, 2B and2C (Scanning Electron Microscope image), the structure of themulticapillary device12 is distinctive and dissimilar to conventional spin columns and silica-based adsorptive and membranous “plugs” (seeFIGS. 3 and 11), which feature irregular voids and vastly different sample pathways that entrap biological samples, such that more than half of the sample is usually unrecoverable. Themulticapillary device12 comprises a plurality of uniformcapillary tubes16 having an insolublestationary phase media18 on internal surfaces thereof, thereby permitting a sample inserted into the flow passage of themulticapillary device12 to advance through open and virtually identical pathways. The inner cavity or flow passage of eachcapillary tube16 thus remains unobstructed and impediment free throughout the sample separation process.
• As shown inFIGS. 12 and 13, purified (DNA) sample fragments extracted from the open and unobstructed capillary channels of themulticapillary device12 comprise considerably larger fragments, representing a significant decrease in fragment breakage or “shearing.” These larger fragments generally reflect a better quality of purified sample as compared to conventional porous silica plugs used for sample processing. In the conventional adsorptive and membranous plugs, sample must travel through tortuous and irregular voids in the porous material, whereby portions of the sample lodge in small voids and are unrecoverable. Fragment shearing is thus unavoidable. With its open and unobstructed channel structure, themulticapillary device12 of the present invention achieves substantial uniformity and consistency as compared to the sponge-like and expansive porous silica materials currently used for sample preparation.
• Due to the significant reduction in sample loss enabled by the open and unobstructed channel structure of themulticapillary device12, it is unnecessary for sample to be passed through the separation materials multiple times, as required in existing porous silica plugs, particles (for proteins and peptides), and fibers (for DNA and RNA). As a result, themulticapillary device12 is generally reusable and fits conveniently with automatic instrumentation because there is no contamination due to sample carry-over. In short, thepresent multicapillary device12 demonstrates superior characteristics over conventional adsorptive and membranous plugs with respect to binding capacity, recovery, increased throughput, uniformity and reproducibility.
• In one embodiment of the invention, the imperforate inner walls of thecapillary tubes16 include particles of inert material or a nodular or uneven surface for increasing the surface area of themulticapillary device12. In such case, the inner wall may be altered using an etching process in combination with a solvent such as, for example, a mineral acid or base, or an organic acid or base.
• The present invention encompasses the use of anystationary phase18 and surface chemistry adapted for liquid chromatography and sample preparation applications. In some embodiments, thestationary phase media18 deposited on inner surfaces of the capillary wall comprises a monolayer of organic molecules, biopolymers or larger particles. Such molecules and particles include, but are not limited to, hydrocarbons and their C-, N-, S- , and P-derivatives; proteins, nucleic acids, and polysaccharides; linear and cross-linked polysiloxanes and other polymers; and viruses and cells. In other embodiments, astationary phase coating18 is formed by treating inner surfaces of thecapillaries16 with organosilicone compounds and further modifying these groups with appropriate reagents and particles.
• An alternative technique for the deposition of astationary phase18 involves polymerization of unsaturated compounds, such as butadiene, styrene, divinylbenzene, and others, on inner walls of thecapillary tubes16.
• The techniques used for deposition of astationary phase material18, described in the following Examples, render the stationary phase material insoluble in organic and water-organic solvents commonly used in sample preparation and liquid chromatography, such as acetonitrile, methanol, isopropanol, acetone, dimethylsulfoxide, dimethylformamide and urea; acetic, iodoacetic, trifluoroacetic and formic acids; and phosphate, acetic and carbonate buffers, etc.
• The multicapillarysample preparation device12 is advantageously suited for use with a wide range of sample preparation and analytical instruments. As shown inFIGS. 1, 4, and5, these include, but are not limited to, manual and automatic pipettes andmicropipettes20,syringes22, disposable devices, and automatic sample handling instruments. In some embodiments, themulticapillary device12 is inserted about the terminal portion of apipette tip20 or other appropriate housing by, for example, sliding or press fitting, and is detachably retained in place by mechanical means such as elastic sealing rings and/or walls of the housing.
• In other embodiments, themulticapillary device12 is integrally and permanently embedded (e.g., cast-in-place) about the terminal region of apipette tip20 or other housing by melting, heat shrinking or adhesion in order to fuse themonolithic element14 to the surface of apipette tip20 or other housing commonly made from polypropylene or other thermoplastic material. As an alternative, plasma and/or chemical means may be used to accomplish adhesion of themonolithic element14 to the surface of thepipette tip20 or other housing.
• In yet another embodiment, themulticapillary device12 is adapted to be detachably or fixedly engaged or aligned with the hollow flow passage(s) of a substantially cylindrical, conical or other housing configuration. Themulticapillary device12 is suitably sized and shaped to be integrated in housings of varying sizes and configurations. However, it is preferable that the housing have a volume in the range of about 0.1 μL to about 100 mL, more preferably in the range of about 1 to about 1000 μL, and most preferably in the range of about 2 to about 200 μL.
• It will be understood that any technique used to install themulticapillary device12 into a pipette tip or other housing for operation with apipette20 should accurately direct sample in a liquid phase through thecapillary tubes16 of themonolithic element14 without bypassing theelement14. In such adaptation, themulticapillary device12 receives the sample at its first end, and a concentrated and/or purified sample, devoid of contaminants such as salts and buffers, is discharged at a second end. Themulticapillary device12 of the present invention is freely permeable not only to proteins, peptides, polynucleotides, and other molecules and biopolymers, but also to viruses, spores, cells (e.g., cancer and stem), and microorganisms. It will be understood, however, that sample molecules are prevented from diffusing from onecapillary tube16 to another
• Preferred materials for fabricating themonolithic element14,capillary tubes16, tips, pipettes20,syringes22 and other housings of the present invention include, but are not limited to, glass, fused silica, ceramic, metal (e.g., stainless steel), and plastic (e.g., polypropylene, polyethylene, polyolefin, or polyetheretherketone). In sample preparation and chromatographic applications, it is desirable to employ a large number (e.g. hundreds or thousands) of capillary tubes to provide an abundant surface area for higher sample loading capacity. It will be understood, however, that the number and dimensions of themulticapillary device12,stationary phase media18, solvent, tips and other housings employed in the invention will vary according to application.
• As an example, the number ofcapillary tubes16 provided in amulticapillary device12 may range from about 100 to about 1,000,000. The inner diameter of eachcapillary tube16 may range from about 0.1 μm to about 200 μm. The outer diameter of themonolithic element14 may range from about 0.1 mm to about 1 m, and the length may range from about 0.1 mm to about 2 m. In a preferred embodiment, the number ofcapillary tubes16 ranges from about 1000 to about 10,000, the inner diameter of each capillary ranges from about 5 μm to about 100 μm, the outer diameter of themonolithic element14 ranges from about 1 mm to about 20 mm, and the length ranges from about 1 mm to about 250 mm.
EXAMPLESExample 1
• C-1 Stationary Phase
• A 5% solution of trimethylchlorosilane in toluene is pumped at 10 μL/min for six hours through a 1 mm outer diameter×25 mm long multicapillary glass rod pierced with approximately 4400 capillaries of 10 μm diameter at 105° C. The multicapillary rod is rinsed with toluene, acetone and methanol, and dried with a nitrogen stream.
Example 2
• C-4 Stationary Phase
• A 10% solution of butyldimethylchlorosilane in toluene is pumped at 40 μL/min for six hours through a 2 mm outer diameter×300 mm long multicapillary glass rod pierced with approximately 4600 capillaries of 25 μm diameter at 105° C. The multicapillary rod is rinsed with toluene, acetone and methanol, and dried with a nitrogen stream.
Example 3
• C-8 Stationary Phase
• A 10% solution of octyltrichlorosilane in toluene is pumped at 50 μL/min for six hours through a 2.3 mm outer diameter×25 mm long multicapillary glass rod pierced with approximately 1400 capillaries of 40 μm diameter at 105° C. The multicapillary rod is rinsed with toluene, acetone and methanol, and dried with a nitrogen stream.
Example 4
• C-12 Stationary Phase
• A 5% solution of dodecyltrichlorosilane in toluene is pumped at 75 μL/min for six hours through a 6 mm outer diameter×300 mm long multicapillary glass rod pierced with approximately 3300 capillaries of 65 μm diameter at 105° C. The multicapillary rod is rinsed with toluene, acetone and methanol, and dried with a nitrogen stream.
Example 5
• C-18Stationary Phase 1
• A 10% solution of octadecyltriethoxysilane in toluene is pumped at 10 μL/min for six hours through a clean and dry 2.3 mm outer diameter×300 mm multicapillary glass rod pierced with approximately 4,000 capillaries of 20 μm diameter at 105° C. While pumping the solution, an opposite end of the multicapillary device is moved at a linear speed of 0.5 mm/min inside an oven heated to 150° C. The device is rinsed with toluene, acetone and methanol, and dried with a nitrogen stream.
Example 6
• C-18Stationary Phase 2
• Twenty 1 mm outer diameter×2.5 mm long multicapillary glass rods pierced with approximately 4400 capillaries of 10 μm diameter are placed in a flask containing 50 mL of a 5% solution of octadecyldimethylchlorosilane in toluene and equipped with a reflux condenser and a calcium chloride tube. The mixture is slowly refluxed for six hours. The liquid phase is separated and the multicapillary rods are repeatedly washed with toluene, tetrahydrofuran and methanol, and dried at room temperature.
Example 7
• C-16, C-30, Phenyl, Naphthyl, and Cyano Stationary Phases
• In accordance with the conditions described in Example 6, the stationary phases with C-16, C-30, phenyl, naphthyl and cyano groups are prepared, correspondingly, from hexadecyltrichlorosilane, triacontyltrichlorosilane, phenethyltrichlorosilane, (1-naphthylmethyl)trichlorosilane and 3-cyanopropyltrichlorosilane.
Example 8
• Epoxide Stationary Phase
• Twenty 2.3 mm outer diameter×5 mm long multicapillary glass rods pierced with approximately 1400 capillaries of 40 μm diameter are placed in a flask containing 50 mL of a 5% solution of (3-glycidoxypropyl)trimethoxysilane in toluene and equipped with a reflux condenser. The mixture is slowly refluxed for five hours while the condenser is maintained at a temperature of 70° C. to remove the methanol formed from the reaction. The liquid phase is separated and the multicapillary rods are repeatedly washed with toluene, tetrahydrofuran and methanol, and dried at room temperature.
Example 9
• DiolStationary Phase 1
• Twenty 2.3 mm outer diameter×3 mm long multicapillary glass rods pierced with approximately 1400 capillaries of 40 μm diameter are placed in a flask containing 50 mL of a 5% solution of (3-glycidoxypropyl)trimethoxysilane in toluene and equipped with a reflux condenser. The mixture is slowly refluxed for three hours while the condenser is maintained at a temperature of 70° C. The liquid phase is separated and the multicapillary rods are repeatedly washed with toluene, tetrahydrofuran, methanol and water. 50 mL of water is added and the pH is adjusted to 2.0 with nitric acid. The mixture is slowly agitated for two hours at room temperature. The liquid phase is separated and the multicapillary rods are washed with water until the wash is neutral, then washed three times with methanol, and dried at room temperature.
Example 10
• DiolStationary Phase 2
• 2.5 g of (3-glycidoxypropyl)trimethoxysilane is dropped into a flask containing 50 mL of water, while maintaining the pH between 5 and 6 with 0.01 M potassium hydroxide. Twenty 2.3 mm outer diameter×5 mm long multicapillary glass rods pierced with approximately 1400 capillaries of 40 μm diameter are placed in a flask. The mixture is slowly refluxed for three hours with a reflux condenser. The liquid phase is separated and the multicapillary rods are repeatedly washed with water, methanol and tetrahydrofuran. 50 mL of water is added and the pH is adjusted to 2.0 with nitric acid. The mixture is slowly agitated for two hours at room temperature. The liquid phase is separated and the multicapillary rods are washed with water until the wash is neutral, then washed three times with methanol, and dried at room temperature.
Example 11
• Amino Stationary Phase
• Twenty-five 1 mm outer diameter×2.5 mm long multicapillary glass rods pierced with approximately 4400 capillaries of 10 μm diameter are placed in a flask containing 50 mL of a 5% solution of 3-aminopropyltrimethoxysilane in toluene and equipped with a reflux condenser. The mixture is slowly refluxed for five hours while the condenser is maintained at a temperature of 70° C. The liquid phase is separated and the multicapillary rods are repeatedly washed with toluene, tetrahydrofuran and methanol, and dried at room temperature.
Example 12
• Trimethylammonium Stationary Phase
• Thirty 2.3 mm outer diameter×5 mm long multicapillary glass rods pierced with approximately 1400 capillaries of 40 μm diameter are placed in a flask containing 50 mL of a 5% solution of 3-aminopropyltrimethoxysilane in toluene and equipped with a reflux condenser. The mixture is slowly refluxed for six hours while the condenser is maintained at a temperature of 70° C. The liquid phase is separated and the multicapillary rods are repeatedly washed with toluene, tetrahydrofuran and methanol. 30 mL of a 5% solution of trimethylamine in methanol is added to the flask. The flask is equipped with a calcium chloride tube, and the mixture is slowly agitated at 0-5° C. for 48 hours. The liquid phase is separated and the multicapillary rods are repeatedly washed with methanol, water, 0.01 M HCl, water and tetrahydrofuran, and dried at room temperature.
Example 13
• Carboxylic Acid Stationary Phase
• Twenty 2.3 mm outer diameter×5 mm long multicapillary glass rods pierced with approximately 1400 capillaries of 40 μm diameter are placed in a flask containing 50 mL of a 5% water solution of carboxyethylsilane triol (sodium salt). The pH is adjusted to 2.0 by adding hydrochloric acid. The mixture is slowly refluxed for three hours with a reflux condenser. The liquid phase is separated and the multicapillary rods are washed with water until the wash is neutral, then washed three times with methanol, and dried at room temperature.
Example 14
• Sulfonic Stationary Phase
• Twenty-five 2.3 mm outer diameter×3 mm long multicapillary glass rods pierced with approximately 1400 capillaries of 40 μm diameter are placed in a flask containing 50 mL of a 5% water solution of 3-(trihydroxysilyl)-1-propanesulfonic acid. The mixture is slowly refluxed for three hours with a reflux condenser. The liquid phase is separated and the multicapillary rods are washed with water until the wash is neutral, then washed three times with methanol, and dried at room temperature.
Example 15
• Phosphonic Stationary Phase
• Thirty 2.3 mm outer diameter×3 mm long multicapillary glass rods pierced with approximately 1400 capillaries of 40 μm diameter are placed in a flask containing 50 mL of a 5% water solution of (3-trihydroxysilylpropyl)methylphosphonate sodium salt. The mixture is acidified to pH 2.0 with HCL and slowly refluxed for three hours with a reflux condenser. The liquid phase is separated and the multicapillary rods are washed with water until the wash is neutral, then washed three times with methanol, and dried at room temperature.
Example 16
• Iminodiacetic Acid Stationary Phase
• Twenty 1 mm outer diameter×2.5 mm long multicapillary glass rods pierced with approximately 4400 capillaries of 10 μm diameter are placed in a flask containing 50 mL of a 5% solution of (3-glycidoxypropyl)trimethoxysilane in toluene and equipped with a reflux condenser. The mixture is slowly refluxed for five hours while the condenser is maintained at a temperature of 70° C. The liquid phase is separated and the multicapillary rods are repeatedly washed with toluene, tetrahydrofuran, methanol and water. 20 mL of a 2 M iminodiacetic acid solution in 0.1 M sodium borate buffer, pH 8.5, is added and the mixture is slowly agitated for 24 hours at room temperature. The liquid phase is separated and the multicapillary rods are washed with water until the wash is neutral, then washed three times with methanol, and dried at room temperature.
Example 17
• Cystein Stationary Phase
• Twenty-five 1 mm outer diameter×2.5 mm long multicapillary glass rods pierced with approximately 4400 capillaries of 10 μm diameter are placed in a flask containing 50 mL of a 5% solution of 3-bromopropyltrimethoxysilane in toluene and equipped with a reflux condenser. The mixture is slowly refluxed for five hours while the condenser is maintained at a temperature of 70° C. The liquid phase is separated and the multicapillary rods are repeatedly washed with toluene, tetrahydrofuran and methanol. 50 mL of a 1% solution of cystein in methanol and 1 mL of triethylamine are added, and the mixture is slowly refluxed with a reflux condenser for five hours. The liquid phase is separated and the multicapillary rods are repeatedly washed with methanol, water, methanol and methylene chloride, and dried at room temperature.
Example 18
• Glutathione Stationary Phase
• Twenty 1 mm outer diameter×2.5 mm long multicapillary glass rods pierced with approximately 4400 capillaries of 10 μm diameter are placed in a flask containing 50 mL of a 5% solution of 11-bromoundecyltrimethoxysilane in toluene and equipped with a reflux condenser. The mixture is slowly refluxed for five hours while the condenser is maintained at a temperature of 70° C. The liquid phase is separated and the multicapillary rods are repeatedly washed with toluene, tetrahydrofuran and methanol. 50 mL of a 0.5% solution of glutathione in methanol and 1 mL of triethylamine are added, and the mixture is slowly refluxed with a reflux condenser for five hours. The liquid phase is separated and the multicapillary rods are repeatedly washed with methanol, water, methanol and methylene chloride, and dried at room temperature.
Example 19
• Chiral Stationary Phase
• A 5% solution of (R)-N-1-phenylethyl-N-triethoxysilylpropylurea in toluene is pumped at 10 μL/min for six hours through a 1 mm outer diameter×300 mm long multicapillary glass rod pierced with approximately 4000 capillaries of 10 μm diameter at 105° C. The multicapillary rod is rinsed with toluene, tetrahydrofuran and methanol, and dried with a nitrogen stream.
Example 20
• Polybutadiene Stationary Phase
• The 10% solution of vinyltrichlorosilane in isooctane is pumped at 20 μL/min for six hours through a 1 mm outer diameter×25 mm long multicapillary glass rod pierced with approximately 4,400 capillaries of 10 μm diameter at 90° C. The multicapillary rod is rinsed with isooctane, tetrahydrofuran, methanol, toluene and isooctane. A solution of 100 mg polybutadiene (MW 3,400) and 0.5 mg dicumyl peroxide in 100 mL of isooctane is pumped at 10 μL/min for six hours through the multicapillary rod at 90° C. The multicapillary rod is rinsed with toluene, tetrahydrofuran and methanol, and dried with a nitrogen stream.
Example 21
• Biotin Stationary Phase
• Twenty five 1 mm outer diameter×2.5 mm long multicapillary glass rods pierced with approximately 4400 capillaries of 10 μm diameter are placed in a flask containing 50 mL of a 5% solution of 3-aminopropyltrimethoxysilane in toluene and equipped with a reflux condenser. The mixture is slowly refluxed for five hours while the condenser is maintained at a temperature of 70° C. The liquid phase is separated and the multicapillary rods are repeatedly washed with toluene, methanol and dimethylformamide.15 mL of a saturated dimethylformamide solution of biotin, a solution of 0.3 g of 1-hydroxybenzotriazole hydrate in 10 mL of dimethylformamide, and a solution of 0.25 g of N, N-dicyclohehylcarbodiimide in 10 mL of dimethylformamide are added, and the mixture is slowly agitated for five hours at room temperature. The liquid phase is separated and the multicapillary rods are repeatedly washed with dimethylformamide, methanol, water, methanol and methylene chloride, and dried at room temperature.
Example 22
• Heparin Stationary Phase
• Twenty 2.3 mm outer diameter×2.5 mm long multicapillary glass rods pierced with approximately 1400 capillaries of 40 μm diameter are placed in a flask containing 50 mL of a 5% solution of 3-aminopropyltrimethoxysilane in toluene and equipped with a reflux condenser. The mixture is slowly refluxed for five hours while the condenser is maintained at a temperature of 70° C. The liquid phase is separated and the multicapillary rods are repeatedly washed with toluene, methanol, water and 0.05 M 2-morpholinoethane sulfonic acid buffer, pH 5.6. The 10 mL solution of 0.2 g heparin (from bovine kidney), 1 g N-(3-dimethylaminopropyl)-N-ethylcarbodiimide, and 0.5 g N-hydroxysuccinimide in 0.05 M 2-morpholinoethane sulfonic acid buffer, pH 5.6, is added. The mixture is slowly agitated for three hours at room temperature. The liquid phase is separated, and the multicapillary rods are repeatedly washed with water, phosphate buffer,pH 8, and 20% sodium chloride, and then washed with water and stored at 4° C.
Example 23
• Glycoprotein Stationary Phase
• Twenty 2.3 mm outer diameter×3 mm long multicapillary glass rods pierced with approximately 1400 capillaries of 40 μm diameter are placed in a flask containing 20 mL of a 5% solution of (3-glycidoxypropyl)trimethoxysilane in toluene and equipped with a reflux condenser. The mixture is slowly refluxed for five hours while the condenser is maintained at a temperature of 70° C. The liquid phase is separated and the multicapillary rods are repeatedly washed with toluene, methanol and water. The 4 mL solution of 100 mg alpha1 acid (from bovine plasma) in a 1:1 mixture of 0.4 M sodium chloride and 0.2 M borate buffer, pH 8.5, is added. The mixture is slowly agitated at room temperature for 48 hours. The liquid phase is separated. The multicapillary rods are repeatedly washed with a 1:1 mixture of 0.4 M sodium chloride and 0.2 M borate buffer, pH 8.5, then washed with water and stored at 4° C.
Example 24
• Trypsin Stationary Phase
• Twenty 2 mm outer diameter×5 mm long multicapillary glass rods pierced with approximately 4600 capillaries of 25 μm diameter are placed in a flask containing 20 mL of a 5% solution of (3-glycidoxypropyl)trimethoxysilane in toluene and equipped with a reflux condenser. The mixture is slowly refluxed for five hours while the condenser is maintained at a temperature of 70° C. The liquid phase is separated and the multicapillary rods are repeatedly washed with toluene, methanol and water. A 7 mL solution of 100 mg trypsin (from bovine pancreas) in 0.2 M phosphate buffer, pH 7.0, is added to the flask. The mixture is slowly agitated at room temperature for 15 hours, and the liquid phase is separated. The multicapillary rods are repeatedly washed with 0.2 M phosphate buffer, pH 7.0, water, 0.2 M Tris buffer, pH 7.5, for two hours, and then washed with water and stored at 4° C.
Example 25
• Avidin, Lectin, and Protein A Stationary Phases
• In accordance with the conditions described in Example 24, avidin, lectin and protein A stationary phases are prepared using avidin (from egg white), lectin (fromAgaricus bisporus), and protein A (fromStaphylococcus aureus), correspondingly.
Example 26
• Antibody Stationary Phase
• Twenty 2.3 mm outer diameter×3 mm long multicapillary glass rods pierced with approximately 1400 capillaries of 40 μm diameter are placed in a flask containing 50 mL of a 5% solution of 10-(carbomethoxy)decyldimethylmethoxysilane in toluene and equipped with a reflux condenser. The mixture is slowly refluxed for three hours while the condenser is maintained at a temperature of 70° C. The liquid phase is separated, and the multicapillary rods are repeatedly washed with toluene, methanol and methylene chloride. A 35 mL solution of 1 mL trimethyliodosilane in methylene chloride is added. The mixture is slowly agitated for 72 hours at room temperature.
• The liquid phase is separated and the multicapillary rods are repeatedly washed with methylene chloride, methanol, 90% methanol and water. 20 mL of 0.02 M ethyl(dimethylaminopropyl)-carbodiimide in 0.1 M 2-morpholinoethanesulfonic acid buffer, pH 4.5, is added, and the mixture is slowly agitated for one hour at room temperature. The liquid phase is separated, and 5 mL of the 5 μg/mL solution of ricin antibody in 0.1 M phosphate buffered saline, pH 7.2, is added. The mixture is slowly agitated for two hours at room temperature. The liquid phase is separated. The multicapillary rods are repeatedly washed with phosphate buffered saline, pH 7.2, then washed with water and stored at 4° C.
Example 27
• Polypropylene Pipette Tip Format Multicapillary Sample Preparation Device
• A 1 mm to 5 mm outerdiameter multicapillary element10, prepared as described in Example 6, is tightly pushed to the lower end of apolypropylene 10 μL to 5,000 μL volume micropipette tip. The lower portion of the pipette tip is placed for ten minutes in an oven thermostated at a temperature at which polypropylene begins to soften. Polypropylene pipette tip format multicapillary devices forsample preparation12,20 are shown inFIGS. 4A and 4B.
Example 28
• Polyethylene Pipette Format Multicapillary Sample Preparation Device
• A 1 mm to 5 mm outerdiameter multicapillary element10, prepared as described in Example 6, is tightly placed in the lower end of a disposable polyethylene transfer pipette. The lower portion of the pipette is placed for ten minutes in an oven thermostated at a temperature at which polyethylene begins to soften. A polyethylene pipette format multicapillary device forsample preparation12,20 is shown inFIG. 4C.
Example 29
• Syringe Format Multicapillary SamplePreparation Device #1
• A 2 mm outerdiameter multicapillary element10, prepared as described in Example 5, is attached to a heat shrinkable tubing. A removable syringe needle is attached to the second end of the heat shrinkable tubing. The heat shrinkable tubing zone is heated at a temperature recommended for the shrinkable tubing for ten minutes A representative syringe format multicapillary device forsample preparation12,22 is shown inFIG. 5A.
Example 30
• Syringe Format Multicapillary SamplePreparation Devices #2 and #3
• A 2.3 mm outerdiameter multicapillary element10, prepared as described in Example 5, is tightly placed in a removable thermoplastic syringe hub. The hub is heated for ten minutes in an oven thermostated at a temperature at which thermoplastic begins to soften. Syringe format multicapillary devices forsample preparation12,22 are shown inFIGS. 5B and 5C.
Example 31
• Separation of Three Component Mixture
• A three component mixture (uracil, fluorene, and phenanthrene) is separated on the multicapillary device for sample preparation prepared as described in Example 5 and installed on a model LC-600 Shimadzu liquid chromatographic instrument using standard HPLC fittings. The chromatographic conditions and chromatogram are reproduced inFIG. 6. The chromatogram shows a uracil peak at about 1.8 minutes, a fluorene peak at about 2.1 minutes, and a phenanthrene peak at about 2.4 minutes. The example illustrates a liquid chromatographic application using the multicapillary device for sample preparation of the present invention, which enables a typical organic mixture to be analyzed in less than three minutes.
Example 32
• Sample Enrichment for HPLC Analysis
• Referring toFIG. 7A, a 2.3 mm outer diameter×100 mm length multicapillary C-18 device for sample preparation containing approximately 1,400 capillaries of 40 μm diameter prepared as described in Example 5 is used for sample enrichment prior to HPLC analysis. At present, short HPLC columns known as solid phase extraction (“SPE”) cartridges are commonly used for sample preparation. Compared to SPE cartridges, multicapillary devices forsample preparation12 are much faster, simpler and reusable. Performance of the present multicapillary device for sample preparation12 (FIG. 7A) as compared to a standard SPE cartridge (FIG. 7B) is shown in Table 1.

  TABLE 1
  Multicapillary Device vs. Conventional SPE Cartridge.

  	Characteristics	SPECartridge	Multicapillary Device

  1	Collection time	20-40 minutes	1-5minutes
  2	Amount	1-5 ml samples	100-200μl samples
  3	Processing the	Extract volume	No concentration
  	extract	5-20 ml	or evaporation of
  		Requires	the extract required
  		evaporation for
  		analysis
  4	Reconditioning	Cannot be	Reconditioned by
  		reconditioned	washing with
  			methanol and water
  			for 2 min.
  5	Reusability	Cannot be	Can be reused at
  		reused	least 50-100
  			times depending on
  			the sample to
  			be extracted
  6	Silica particles	Fine silica	No silica or other
  	in the sample	particles in the	particles in the
  		samples	samples
  7	Auto samplers	Cannot be	Easily adaptable
  	adaptability	used in auto	toauto samplers
  		samplers
  8	Field use	Difficult	Requires only syringes
  		to transport
  		Costly
  		equipment/
  		accessories

Example 33
• Hydrolysis of Bovine Serum Albumin
• A 10 μL volume of 0.25 mg/mL bovine serum albumin solution in a 40:60 mixture of acetonitrile and 0.2 mM ammonium bicarbonate, pH 7.5, is aspirated in the multicapillary sample preparation device, prepared as described in Example 24, and thermostated at 37° C. After five minutes, the digested sample is dispensed in a vial and stored at 4° C.
Example 34
• Desalting of Peptide Samples
• The bovine serum albumin digest, prepared as described in Example 34, is dried with a nitrogen stream and dissolved in 10 μL of 0.1% trifluoroacetic acid (TFA) in water. 1 μL of this sample is aspirated and dispensed from the multicapillary sample preparation device, as described in Examples 5 and 27. Three 10 μL portions of 0.1% trifluoroacetic acid (TFA) in 5% acetonitrile/water are pumped in and out of the multicapillary sample preparation device. The sample is eluted from the multicapillary sample preparation device with a 5 μL portion of 0.1% TFA in 70% acetonitrile/water and analyzed by MALDI-MS. The MALDI-MS spectra of the sample before and after desalting are shown inFIGS. 8A and 8B.
Example 35
• Fractionating of Peptides
• A 3 μL volume of the 100 pmole/μL peptide mixture obtained by the enzymatic hydrolysis of bovine serum albumin, as described in Example 34, is introduced into a 10 cm long C-18 multicapillary sample preparation device. The sample is eluted at 100 μL/min with 100 μL of 0.1% TFA in water followed by 30 μL of 0.1% TFA in 40% acetonitrile/water. Ten 3 μL 40% acetonitrile/water fractions are collected and analyzed by MALDI-MS. The mass-spectra offractions 3 and 6 are shown inFIGS. 9A and 9B. This example illustrates the fractionating ability of the multicapillary sample preparation device of the present invention, prior to MALDI-MS analysis of a complex peptide mixture.
Example 36
• Gel Electrophoresis of Proteins
• FIGS. 10A and 10B depict gels produced to evaluate the sample capacity, recovery, and reproducibility of a multicapillary device for sample preparation according to the present invention, as compared to commercially available porous silica-based devices.Lanes 1 and 10 are protein standards inserted for purposes of comparison.Lanes 2 to 5 represent the conventional devices, whileLanes 3 to 10 denote the multicapillary sample preparation device of the instant invention.
• The test sample used for electrophoresis is a mixture of the following four representative proteins: Phosphorylase B (MW 97,400), Bovine Serum Albumin (MW 66,200), Carbonic Anhydrase (MW 31,000), and Lysozyme (MW 14,400). These proteins were selected due to their varying size and generally known properties. Moreover, these proteins are commonly used as standards. All results were reproduced and retested several times to ensure accuracy. Testing was conducted at ChromBA, Inc. (State College, Pa.), The Materials Research Institute (University Park, Pa.), The Milton Hershey Medical Center (Hershey, Pa.), Huck Institute (University Park, Pa.), APD LifeSciences Inc. (State College, Pa.), and MassTech Inc. (Columbia, Md.). In total, over 40 gels were used, including both C₁₈and C₄, the two most popular phases on the market. In addition, more than 500 sample preparation devices were tested.
• In both figures, the conventional silica-based devices (FIG. 10A: Lanes 2-5; FIG.10B: Lanes 1-2) show faint and varying bands. In contrast, the device of the present invention (FIG. 10A: Lanes 6-9;FIG. 10B: Lanes 3-10) shows bold and dark bands, indicating vastly superior binding capacity, and recovery. Moreover, the bands of the present device are clearly more identical from lane to lane demonstrating superior reproducibility. As shown in Table 2, further quantification reveals that the sample preparation device of the present invention, on average, binds and releases nearly twice the protein bound and released by conventional devices, and demonstrates half the margin of error (i.e., variance in amount of sample bound).

  TABLE 2
  Sample Capacity, Recovery Performance, and Reproducibility
  of Multicapillary Device vs. Conventional Devices.

  	MEAN VALUE	% OF	AVERAGE
  	OF BAND	INCREASED	MARGIN
  	INTENSITY	CAPACITY	OF ERROR

  		Convent.	Multicap.	Multicap.	Convent.	Multicap.
  	PROTEIN	Device	Device	Device	Device	Device

  FIG.	Phosphorylase B	45.7	56.2	23%	5.8%	3.4%
  10A	Bovine Serum	85.2	162.1	91%
  	Albumin
  	Carbonic	86.8	131.4	51%
  	Anhydrase
  	Lysozyme	84.2	151.6	79%
  FIG.	Phosphorylase B	—	—	—	—	—
  10B	Bovine Serum	85.5	135.1	107%	6.3%	3.8%
  	Albumin
  	Carbonic	70.1	108.6	55%
  	Anhydrase
  	Lysozyme	77.0	157.6	104%

• FIG. 10C shows a gel produced to evaluate the speed of use (time performance) of a multicapillary device for sample preparation according to the present invention relative to commercially available silica-based devices. As recommended by the manufacturers, a sample must be passed through the tip of the silica-based devices approximately ten times to achieve suitable results. This is largely due to the fact that most of the sample travels through large voids in the filtration material and is subsequently not adsorbed and cleaned. Specifically, as illustrated by Lanes 1-4 ofFIG. 10C, the conventional devices show faint bands even after ten passes through the tip.
• In contrast, Lanes 5-10 show nearly identical spots for samples passed through the multicapillary device of the present invention only once. Notably, the bands are much darker and broader than those of the silica-based devices, denoting the presence of vastly greater amounts of protein.
• InFIGS. 10A-10C, the darkness and size of the bands on the gels developed by electrophoresis indicate the amount of protein bound by and recovered from the sample preparation devices; namely, pipette tips with integral silica-based plugs versus multicapillary elements. The superior performance of themulticapillary device12 of the present invention is due, in part, to the uniform, consistent and virtually identical pathways for sample passage through the device, along with excellent tip-to-tip duplication, as shown inFIG. 2.FIG. 3 andFIG. 11, in contrast, depict cross-sections of commercially available (market leader) porous silica and silica fiber based sample preparation devices. The silica based devices reveal irregular particle sizes and fiber diameter, large voids (dark areas), and vastly different sample pathways. Moreover, the conventional devices demonstrate poor tip-to-tip duplication (i.e., tremendous variance).
Example 37
• Isolation of Nucleic Acids
• The following experiments, featuring bothsyringe22 andpipette tip20format multicapillary devices12, demonstrate the advantage of using a multicapillary device for sample handling and extraction of DNA from various biological samples, such as tissue, blood, bacterial cells, urine, etc.
• A multicapillary device for sample preparation12 (1 to 2.5 mm outer diameter, 0.25 to 3 cm long, approximately 4000 capillaries of 10 to 40 μm diameter,inner volume 2 to 90 μL) is loaded twice with 10 to 1,000 μL lysed biological sample. After discarding the loading solution, themulticapillary device12 is rinsed with a washing buffer to dispose of proteins and other non-DNA type materials. Adsorbed DNA is then eluted with 10 to 300 μL elution buffer. The eluted DNA is analyzed using a variety of methods including Yo-Pro fluorescence on a Packard FluoroCount instrument at 530 nm (for yield determination), Agarose gel electrophoresis (for quality determination), and pulsed field gel electrophoresis (for DNA size and quality determination).
• FIGS. 13A and 13B, respectively, are bar graphs comparing16 rat liver samples' purification results in terms of DNA yield and time required for sample preparation using 25 μm×1 cm×200 μL pipette tipformat multicapillary devices12,20 according to the present invention and16 commercially available (market leader) spin columns. The data for DNA yield was obtained using Yo-Pro fluorescence, and time was recorded with a stopwatch for each sample. The experiments demonstrate that themulticapillary devices12 of the present invention are comparable to conventional spin columns in terms of DNA yield, but require significantly less time for processing. Notably, use of the present multicapillary devices results in a seven-fold decrease in “hands-on” labor time for DNA isolation sample preparation.
• Agarose gel electrophoresis and pulsed field gel electrophoresis analyses were performed to determine DNA quality and size.FIG. 12B shows a 0.8% agarose gel run to analyze DNA extracted from whole bovine blood using the pipette tip format multicapillary devices (Lanes 1-7) and commercially available spin columns (Lanes 8-9), demonstrating comparable DNA yields and quality. Further, as shown inFIG. 12A, pulsed field gel electrophoresis was used to size DNA strands of purified samples using themulticapillary device12 of the present invention and commercially available spin columns. As compared to the leading spin columns, samples extracted using thepresent multicapillary device12 demonstrate considerably larger DNA fragments, which suggests a significant decrease in DNA breakage or “shearing” during sample processing. Larger fragments of DNA reflect a better quality of the purified sample, which is highly desirable for many downstream applications such as PCR and sequencing.
• As demonstrated inFIGS. 12 and 13, significant DNA shearing is unavoidable in specimens processed using the commercially available spin columns, which are operated by means of a centrifuge. In themulticapillary device12 of the present invention, however, DNA shearing is largely avoided through the use of an insoluble, surface-mediated mechanism of separation, which ensures that capillary channels (lumens) remain open and unobstructed throughout sample processing. Use of a gentle pipetting procedure for sample processing, in lieu of the commonly employed centrifuge, further contributes to the quality and size of DNA processed by means of themulticapillary devices12 disclosed herein.
• Table 3 shows the adsorbance reading of fivemulticapillary devices12 prepared according to the method described above. The average DNA recovery yield is 50-60%, which demonstrates that the multicapillary device forsample preparation12 is efficacious for sample handling, purification and isolation of nucleic acids.

  TABLE 3
  DNA Isolation on Multicapillary Device.

  	Fluorescence Reading
  Sample	(Units)

  Blank elution buffer	21
  Elution buffer spiked with 16 μg/mL DNA	214
  Eluted DNA from MC	211
  Eluted DNA from MC	211
  Eluted DNA from MC	217
  Eluted DNA from MC	238
  Eluted DNA from MC	213

Example 38
• Sample Handling of Cells
• To demonstrate the use of amulticapillary device12 for sample handling of cells, the following cells are grown and evaluated: mouse myeloma Sp2/0-Ag14, approximately 25 μm size; mouse macrophage J774A1, approximately 15 μm size; and human prostrate tumor THP-1 approximately 20 μm size. A syringe format multicapillary device forsample preparation12,22 (2.3 mm outer diameter, 150 mm long, approximately 1400 capillaries of 40 μm diameter, inner volume 262 μL) is attached to a syringe and rinsed with 1 mL of balanced salt solution creating an environment conductive to cell viability. At room temperature, a 1.5-3.0 mL volume of cell suspension is passed through the multicapillary device at a flow rate of 1 mL/min, followed by a 0.5 mL volume of balanced salt solution. The eluted cell suspension is concentrated by centrifugation and cells are counted using a hemacytometer. The change in cell viability after passage through the multicapillary device is presented in Table 4.

  TABLE 4
  Cell Viability Upon Passage Through Multicapillary Device.

  			Viable		% Viable
  	Suspension	Concentration	Cells	Viable Cells	Cells
  Cell	Volume	of Cells	Initial	Recovered	Recovered
  Sp2/0-Ag14	3.0mL	1 × 106cells/mL	2.73 × 106	2.09 × 106	76.5
  J774A1	2.0 mL	3.5 × 106cells/mL	6.30 × 106	3.57 × 106	56.6
  THP-1	2.0 mL	3.5 × 106cells/mL	6.65 × 106	5.06 × 106	76.1

• The data reveal that the vast majority of each cell type passed through the device emerges unharmed. Therefore, the multicapillary device for sample preparation is highly efficacious for sample handling of cells.
• Manufacturers of existing pipette tips state in their technical literature that 40-60% sample loss is average for a purified product. In comparison, the increased capacity and recovery afforded by the present invention substantially reduces and/or eliminates the critical problem of sample loss in the pipette tip. Moreover, equipment wear is reduced, since the present invention eschews repeat sample passage, as required by conventional silica-based devices.
• As demonstrated by the foregoing Examples 1-38, themulticapillary device12 of the present invention enables a user to achieve superior sample preparation results in significantly less time. Indeed, the device's12 ability to return quality results quickly and reproducibly permits a user to increase the throughput of available sample preparation stations at least several times, depending upon the sample and system employed.
• In short, the multicapillarysample preparation device12 of the present invention advantageously increases sample throughput and decreases variance in a highly reproducible fashion. Themulticapillary device12 may be used in an array of applications without departing from the scope of the invention. These include, but are not limited to, sample handling of small molecules, polymers, viruses and cells; the isolation, purification, concentration, desalting and fractionation of biological samples and nucleic acids, including DNA and RNA; solid phase extraction; head space analysis; gas chromatography; liquid chromatography (e.g., HPLC); supercritical chromatography; electrochromatography; and capillary electrophoresis.
• Representative examples of the above-mentioned applications include: sample preparation of biological samples such as proteins, peptides, and polynucleotides, fractionation of peptide mixtures prior to mass-spectrometric analysis, desalting of samples prior to instrumental analysis, desalting of peptide solutions, desalting of protein solutions, sample concentration prior to instrumental analysis, and peptide concentration prior to mass-spectrometric analysis.
• While the invention has been particularly shown and described with reference to the examples and preferred embodiments thereof, it will be understood by those skilled in the art that various alterations in form and detail may be made therein without departing from the spirit and scope of the invention.

Claims (25)

1. A sample preparation device, especially useful for handling biological samples, comprising:

(a) an element for receiving a sample at an upper end thereof and discharging a concentrated, purified, or separated sample at a lower end of the element, said element defining a cavity;

(b) a plurality of capillary tubes arranged within said cavity, each capillary tube defining an inner bore having an inner wall and first and second openings; and

(c) a housing of substantially cylindrical or conical configuration for retaining the multicapillary element, said housing being suitable for attachment to a sample preparation or analytical instrument.

2. The sample preparation device ofclaim 1 wherein a stationary phase is deposited on the inner wall of said capillary tubes without an intermediary constituent.

3. The sample preparation device ofclaim 2 wherein the inner bore of said capillary tubes is unobstructed by said stationary phase; and

the stationary phase comprises a thickness that is correlated with the radius of individual capillary tubes for high efficiency.

4. The sample preparation device ofclaim 2 or3 wherein the stationary phase is insoluble.

5. The sample preparation device ofclaim 4 wherein the insoluble stationary phase is chemically bonded to the inner wall of said capillary tubes.

6. The sample preparation device ofclaim 4 wherein the insoluble stationary phase is cross-linked to the inner wall of said capillary tubes.

7. The sample preparation device ofclaim 4 wherein the insoluble stationary phase is both cross-linked and chemically bonded to the inner wall of said capillary tubes.

8. The sample preparation device ofclaim 2 or3 wherein the thickness of said stationary phase coating is proportional to the radius of said capillary tubes in power n, where n is greater than1.

9. The sample preparation device ofclaim 2 or3 wherein the following relationship holds:

d_f(r)=c_f·rⁿ

where d_f=insoluble stationary phase thickness; c_f=constant; r=capillary radius; and n>1.

10. A sample preparation device, especially useful for handling biological samples, comprising:

(a) an element for receiving a sample at an upper end thereof and discharging a concentrated, purified, or separated sample at a lower end of the element, said element defining a cavity;

(b) a plurality of capillary tubes arranged within said cavity, each capillary tube defining an inner bore having an inner wall and first and second openings, said capillary inner wall having an imperforate structure;

(c) a housing of substantially cylindrical or conical configuration for retaining the multicapillary element, said housing being suitable for attachment to a sample preparation or analytical instrument; and

(d) wherein the imperforate structure of said capillary inner wall prevents the sample from diffusing from one capillary tube to another during separation.

11. The sample preparation device ofclaim 10 wherein a stationary phase is deposited on the imperforate inner wall of said capillary tubes without an intermediary constituent.

12. The sample preparation device ofclaim 11 wherein the inner bore of said capillary tubes is unobstructed by said stationary phase; and

the stationary phase comprises a thickness that is correlated with the radius of individual capillary tubes for high efficiency.

13. The sample preparation device ofclaim 11 or12 wherein the stationary phase is insoluble so as to prevent discharge of said stationary phase into a mobile phase during separation.

14. The sample preparation device ofclaim 2 or3 wherein the following relationship holds:

d_f(r)=c_f·rⁿ

where d_f=insoluble stationary phase thickness; c_f=constant; r =capillary radius; and n>1.

15. The sample preparation device ofclaim 1 or10 wherein said multicapillary element is formed of fused silica, glass, ceramic, stainless steel, or polyetheretherketone.

16. The sample preparation device ofclaim 1 or10 wherein an inner diameter of one or more of said capillary tubes is in the range of about 0.1 μm to about 200 μm.

17. The sample preparation device ofclaim 1 or10 wherein an outer diameter of said multicapillary element is in the range of about 0.1 mm to about 20 mm.

18. The sample preparation device ofclaim 1 or10 wherein a length of said multicapillary element is in the range of about 0.1 mm to about 250 mm.

19. The sample preparation device ofclaim 1 or10 wherein a volume of said housing is in the range of about 0.1 μL to about 100 mL.

20. The sample preparation device ofclaim 1 or10 wherein said housing is formed of polyolefin, polyetheretherketone, glass, fused silica, ceramic, or stainless steel.

21. The sample preparation device ofclaim 1 or10 wherein the inner wall of said capillary tubes includes particles of inert material for increasing surface area of the tubes.

22. The sample preparation device ofclaim 1 or10 wherein the inner wall of said capillary tubes includes a nodular surface for increasing surface area of the tubes.

23. The sample preparation device ofclaim 1 or10 wherein said sample comprises a protein, peptide, polynucleotide, biopolymer, virus, spore, cell, microorganism, nucleic acid, or other biological specimen.

24. The sample preparation device ofclaim 1 or10 wherein said housing comprises a tip, pipette, micropipette, or syringe.

25. A method of preparing a sample preparation device, especially useful for handling biological samples, comprising:

(a) introducing a stationary phase solution into an element containing a plurality of capillary tubes for receiving a sample at a first end of the element and discharging a separated sample at a second end of the element;

(b) simultaneously exposing the element to an environment that facilitates evaporation of the solution;

(c) cross-linking or chemically bonding the stationary phase to the interior of said capillary tubes; and

(d) wherein the stationary phase comprises a thickness that is correlated with the radius of individual capillary tubes for high efficiency.

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