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  Continuous biomolecule separation in a nanofilterRelated Patent Categories: Classifying, Separating, And Assorting Solids, Special ApplicationsContinuous biomolecule separation in a nanofilter description/claimsThe Patent Description & Claims data below is from USPTO Patent Application 20070090026, Continuous biomolecule separation in a nanofilter. Brief Patent Description - Full Patent Description - Patent Application Claims
CROSS REFERENCE TO RELATED APPLICATIONS [0001] This Application claims the benefit of U.S. Provisional Application Ser. No. 60/723,926, filed Oct. 6, 2005, which is hereby incorporated in its entirety. FIELD OF THE INVENTION [0003] This invention is directed to sorting devices comprising nanoseparation matrices, an apparatus comprising the same, and methods of use thereof for high throughput molecular separations. BACKGROUND OF THE INVENTION [0004] In systems biology, and in the application of biomarker detection and biosensing, the separation and identification of many proteins, small molecules, and carbohydrates from a cell or from complex biological samples, is necessary. Often, one needs to profile the concentrations of many different biomarkers, cytokines and other signaling molecules contained in serum, to determine or diagnose the current progress of a disease. However, these biomarkers (typically smaller than 30 kD) are present at relatively low concentrations (pM.about.nM), while majority proteins (albumin and globulins, typically larger than 40 kD) are present at much higher concentrations (.mu.M.about.mM), which critically limits the detection of the smaller biomarkers. [0005] Pre-fractionation and separation could eliminate background molecules to enhance the detection ability of the signaling molecules, but none of the conventional separation techniques is appropriate for this task. Gel electrophoresis is routinely used for separating proteins based on size, but they are generally slow and hard to automate, and require bulky equipment. Capillary Electrophoresis (CE) with a liquid sieving matrix is currently the fastest size-based separation technique for protein, but polymeric sieving matrix can interfere with downstream separation and detection processes, which limits the automation of the entire sample preparation process. While microfluidic biomolecule separation systems hold much promise for miniaturizing and automating biomolecule analysis processes, most adopt the same gel sieve material in their separation, with all inherent limitations of the conventional techniques. [0006] Micro/nanofluidic molecular sieving structures fabricated with semiconductor technology have been used to separate biomolecules as well, with much greater speed than their conventional counterparts, though to date the systems have only successfully been used for large biomolecule separation such as viral DNA based on size. [0007] Thus, a high-throughput biomolecular sorter, which can be automated, and can be readily incorporated into downstream analysis modules is desirable, yet is currently not readily accomplished. SUMMARY OF THE INVENTION [0008] In one embodiment, this invention provides a biomolecular sorter comprising: [0009] a) a substrate; [0010] b) a plurality of obstacles arranged at regular intervals in a plurality of rows, columns or combinations thereof on a surface of said substrate; [0011] c) a sample inlet to said sorter; [0012] d) at least a first conduit for applying an electrostatic force field or hydrodynamic force field parallel in direction to said rows; and [0013] e) at least a second conduit for applying an electrostatic force field or hydrodynamic force field parallel in direction to said columns, and perpendicular in direction to said rows; wherein said obstacles are so arranged as to form gaps between said obstacles, with horizontal gaps being of a width less than vertical gaps between said obstacles. [0014] According to this aspect of the invention, and in one embodiment, the horizontal gaps are from about 10-5000 nm, and in another embodiment, the vertical gaps are from about 0.1-10 .mu.m. In another embodiment, the obstacles in the rows are laterally shifted with respect to each row. [0015] In one embodiment, the gaps form channels for fluid conductance, when fluid is introduced in said sorter. In another embodiment, microfluidic channels are in fluid communication with the channels. In one embodiment, channels comprise sample loading ports, and in another embodiment, the channels comprise sample collection ports. [0016] In another embodiment, the microfluidic channels are in fluid communication with a reservoir. In one embodiment, voltage is applied to said reservoir, which in one embodiment is less than 1000 V. In another embodiment, pressure is applied to said reservoir. [0017] In one embodiment, the electrostatic force field or hydrodynamic force field is applied in pulse-field operation mode, or in another embodiment, in continuous-field operation mode. [0018] In another embodiment, this invention provides a method of sorting a fluid mixture comprising a plurality of biopolymers, which vary in terms of the physico-chemical characteristics of each of said plurality of biopolymers, said method comprising the steps of: [0019] a) loading a fluid mixture comprising a plurality of biopolymers in a biomolecular sorter comprising: [0020] i. a substrate; [0021] ii. a plurality of obstacles arranged at regular intervals in a plurality of rows, columns or combinations thereof on a surface of said substrate, wherein said obstacles are so arranged as to form gaps between said obstacles, with horizontal gaps being of a width less than vertical gaps between said obstacles, and said gaps form channels for fluid conductance, when fluid is introduced in said sorter; [0022] iii. a sample inlet to said sorter; [0023] iv. microfluidic channels in fluid communication with said channels; [0024] v. sample collection ports in fluid communication with said channels; [0025] vi. at least a first conduit for applying an electrostatic force field or hydrodynamic force field parallel in direction to said rows; [0026] vii. at least a second conduit for applying an electrostatic force field or hydrodynamic force field parallel in direction to said columns, and perpendicular in direction to said rows; and [0027] b) applying said electrostatic force field or hydrodynamic force field parallel in direction to said rows, and said electrostatic force field or hydrodynamic force field parallel in direction to said columns, and perpendicular in direction to said rows, whereby applying said force fields allows for size-based separation of said plurality of biopolymers through said channels; and [0028] c) collecting separated biopolymers obtained in (b) from said sample collection ports. [0029] According to this aspect of the invention, and in one embodiment, the fluid mixture comprises a cell lysate or tissue homogenate, or in another embodiment, the fluid mixture comprises a large sample of deoxyribonucleic acids (DNA), proteins, or a combination thereof. In another embodiment, the fluid mixture comprises a buffered solution. In another embodiment, the method further comprises the step of sorting a sample of said mixture two or more times, wherein the pH or ionic strength of said buffered solution is varied at the time of said sorting. In another embodiment, the physico-chemical characteristics comprise size, charge, hydrophobicity, hydrophilicity, or a combination thereof. [0030] In one embodiment, the electrostatic force field parallel in direction to the rows provides an electroosmotic driving force for the fluid. According to this aspect of the invention and in one embodiment, the fluid has an ionic strength of about 1-300 mM. [0031] In one embodiment, the sorting is size-based. According to this aspect of the invention and in one embodiment, greater separation of the biopolymers is achieved with increasing voltage. In one embodiment, the voltage applied is at least 60V, or in another embodiment, at least 70V, or in another embodiment, at least 100V, or in another embodiment, at least 150V. [0032] In one embodiment, the fluid has an ionic strength of at least 100 mM. In one embodiment, the fluid has an ionic strength of at least 125 mM, or in another embodiment, at least 150 mM. [0033] In one embodiment, the sorting is charge-based. According to this aspect of the invention and in one embodiment, greater resolution of said biopolymers is achieved when the applied voltage is greater than 40 V. BRIEF DESCRIPTION OF THE DRAWINGS [0034] The subject matter regarded as the invention is particularly pointed out and distinctly claimed in the concluding portion of the specification. The invention, however, both as to organization and method of operation, together with objects, features, and advantages thereof, may best be understood by reference to the following detailed description when read with the accompanying drawings in which: [0035] FIG. 1 schematically depicts negatively charged biomolecules assuming bidirectional motion in the ANA under the influence of two orthogonal electric fields Ex and Ey. On the left, cross-sections of the nanochannels are shown (lighter zones highlight the source of separation), whereas on the right different migration trajectories of biomolecules are presented in the top view of the ANA. Nanofilters (1-20) (with width ws, length ls, and depth ds) arranged in rows are separated by deep channels (1-10) (with width ld and depth dd). Rectangular pillars (1-30) (with width wp and length ls) between nanofilters serve as supporting structures to prevent collapse of the top ceiling. The Debye-length .lamda.D is the thickness of the electrical double layer, .theta. is the deflection angle, and L is the mean characteristic drift distance between two consecutive nanofilter crossings. a, Ogston sieving. Compared to larger DNA or larger native protein molecules, smaller ones are preferred for passage through the nanofilter due to their greater retained configurational freedom, resulting in a greater nanofilter jump passage rate Px. b, Entropic trapping. Longer DNA molecules have larger surface area contacting the nanofilter threshold, resulting in a greater probability for hernia formation and thus a greater nanofilter passage rate Px. c, Electrostatic governed separation by sample net charge for native proteins at low ionic strength. Electrostatic repulsion from the 55-nm-high channels is smaller for less negatively charged (green) than for more negatively charged native proteins (red), resulting in a greater passage rate Px for less negatively charged proteins. [0036] FIG. 2A depicts the structures of an embodiment of the microfabricated two-dimensional nanofilter based device illustrating the sieving matrix integrated with the microfluidic channels. Scanning electron microscopy images show details of different device regions (clockwise from top right: sample injection channels, sample collection channels, and minimal sorting unit). The separation chamber (consisted of rows of nanofilters) is 5 mm.times.5 mm, and the nanofilter has width (Ws) and length (Ls) both of 1 .mu.m. The many microfluidic channels (2-30) connecting to buffer reservoirs (2-20) produce electrostatic force field or hydrodynamic force field over the sieving matrix by acting as electric-current injectors or fluidic flow injectors, which enables separation of materials introduced into the sample reservoir (2-10). The inset shows a photograph of the thumbnail-sized device. The rectangular ANA is 5 mm.times.5 mm, and nanofilters (w.sub.s=1 .mu.m, l.sub.s=1 .mu.m and d.sub.s=55 nm) are spaced by 1 .mu.m.times.1 .mu.m square-shaped silicon pillars. Deep channels are 1 .mu.m wide and 300 nm deep. Injection channels connecting sample reservoir inject biomolecule samples as a 30 .mu.m wide stream. Injection channels are 1 mm from the top left corner. The red rectangle highlights the area in which the fluorescence photographs in FIG. 5 were taken. Continue reading about Continuous biomolecule separation in a nanofilter... Full patent description for Continuous biomolecule separation in a nanofilter Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Continuous biomolecule separation in a nanofilter patent application. ###  How KEYWORD MONITOR works... a FREE service from FreshPatents1. Sign up (takes 30 seconds). 2. Fill in the keywords to be monitored. 3. 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