Nanopores, methods for using same, methods for making same and methods for characterizing biomolecules using same

Info

Publication number: 20070042366
Type: Application
Filed: Feb 13, 2004
Publication Date: Feb 22, 2007
Applicant: Brown University (Providence, RI)
Inventor: Xinsheng Ling (East Greenwich, RI)
Application Number: 10/546,939

Abstract

Featured are devices and systems embodying one or more solid-state nanopores useable for sensing and/or characterizing single macromolecules as well as sequencing DNA or RNA and/or determining RNA secondary structures. In once solid state nanopore of the present invention the width and/or length of the nanopore is defined or established by sharp edges of cleaved crystals that are maintained in fixed relation during the formation of the insulating member including the nanopore. In another aspect of the present invention, there is featured a linear or 2-D electrically addressable array of nanopores, where the nanopores are located at points of intersections between grooves formed in an upper surface of the insulating member and a groove formed in a lower surface of the insulating member.

Description

Description

FIELD OF INVENTION

The present invention relates to devices used for characterizing biomolecules as well as sequencing DNA and RNA, and more particularly to a nanopore and/ or an array of nanopores for use in rapid characterization of biomolecules and high through-put DNA sequencing.

BACKGROUND OF THE INVENTION

Transport of nucleic acids and other biological molecules through membrane channels of nanometer scale is ubiquitous in Nature. Examples include the movement of RNA molecules and transcription factors across nuclear pores; viral DNA injected through a bacterium membrane in phage infection; and the uptake of specific oligonucleotides by membrane proteins. Understanding the function of these nanoscale channels and how biomolecules move through them is a major task of modem molecular biology and biophysics. In recent years, a fascinating field of nanopore biophysics has emerged in the interdisciplinary area of molecular biology, nanotechnology, and single molecule biophysics. In 1994, Berzrukov, Vodyanoy, and Parsegian showed that one can use a biological nanopore as a Coulter counter to count individual molecules. In 1996, in a landmark paper by Kasianowicz, Brandin, Branton, and Deamer (KBBD), [Kasianowicz, L J, Brandin, E, Branton, D. & Deamer, D. W. Characterization of individual polynucleotide molecules using a membrane channel, Proc. Nat Acad. Sci. USA 93, 13770-13773 (1996)] an ambitious idea was proposed for ultrafast single-molecule sequencing of single-stranded (ss) DNA molecules using nanopore ionic conductance as a sensing mechanism. Since then several groups have explored the potential of α-hemolysin protein pore as a possible candidate for achieving this objective.

DNA sequencing using nanopore ionic conductance in accordance with the KBBD method involves an insulating wall separating two reservoirs of ionic solutions, where the wall contains a hole so small that only one strand of a single-stranded DNA molecule can fit through the pore. When a voltage is applied to the two reservoirs, the electrical potential drop should almost entirely occur at the nanopore. Similar to the case of point contact resistance or conductance between two metals, the electrical conductance or resistance between two ionic reservoirs is also the conductance or resistance of the nanopore. Because of the low mobility of the DNA molecule, the ionic conductance through the nanopore is dominated by the flux of Na⁺ and Cl⁻ flushing through the nanopore. The ionic conductance drops when a DNA molecule enters the nanopore.

The amount of conductance drop will be a measure of the physical size of the part of the DNA molecule that is inside the narrowest part of the channel. Because the chemical groups (nucleotides) of a DNA molecule have slightly different sizes, one should be able to measure the genetic information of the nucleotides of a DNA molecule by measuring the time dependence of the nanopore conductance.

The underlying assumption of the KBBD method is that the four different nucleotides composing DNA or RNA molecules may have different blockage effects in the ionic current when the molecule moves through a nanopore, because they have different atomic compositions. The basic concept of voltage driven DNA translocation through a nanopore is illustrated in FIG. 1 that shows (a) a schematic of a voltage-driven DNA translocation experiment using α-hemolysin nanopore and (b) typical translocation events using poly (dA) in buffer 1 M KCI, 1 mM Tris-EDTA (pH 8.5).

There have been encouraging preliminary data suggesting that this idea may be feasible. For example, it has been shown that homopolymers of poly-adenine (DNA) give rise to a slightly lower blockage level than polycytosines, and are translocated in a few μsec per base rate, under room temperature conditions. These findings are indeed very encouraging for the realization of a rapid DNA sequencing method.

The KBBD methodology uses a α-hemolysin protein ion channel embedded in a lipid bilayer membrane as a natural nanopore. It has been demonstrated that a DNA polymer consisting of 70 cytosine nucleotides and 30 adenine nucleotides does give rise to a measurable signal in the nanopore conductance. However, because the natural nanopores are long channels, typically 30 nm in length, many nucleotides are inside the channel at any time during translocation and the effect of individual nucleotides on the ionic conductance is lost. The fact that one can see a difference at all between C and A nucleotides in the nanopore conductance is a sign that one should be able to ultimately see the effect of a single nucleotide on the nanopore conductance, if one can make a nanopore with length comparable to that of a single nucleotide (˜0.4 nm).

There also has been recently demonstrated (Golovchenko's group in the Harvard Physics Department) a reliable nano sculpting approach for making a single nanopore of 1.5 nm in diameter in a silicon-nitride solid-state membrane. In this approach, the processing steps that use focused ion beam lithography and low energy sputtering with feedback monitoring are highly reproducible and reliable, however these nanopores are still too long in length (>10 nm) for measuring single nucleotides. J. Li, D Stein, C McMullan, D Branton, M. J. Aziz, and J. A. Golovchenko; Ion-beam sculpting at nanometer length scales, Nature 412, 166-169 (2001).

In a recent experiment by Meller et al. it was found that the amount of current blockage and the time it takes for the DNA molecule to go through the nanopore channel have large fluctuations. A. Meller, L. Nivon, and D Branton, Voltage-driven DNA translocations through a nanopore, Phys. Rev. Lett. 86, 3435-3438 (2001). There is shown in FIG. 2 histograms illustrating the blockage current versus polymer length (left panel) and the translocation velocity versus polymer length for the same polymer (right panel). Consequently it can be seen that a good understanding of the origin(s) of these fluctuations is needed in order to observe individual bases in the standard DNA translocation experiment. In fact, the physics of how a linear flexible molecule (such as a DNA) threads through a nanopore under the influence of a driving force is poorly understood, making it difficult to extract size information from the ionic current data. There are several theoretical papers addressing various aspects of this problem, such as the effects of fluctuations of polymer ends (entropic barrier), DNA-channel interactions, etc. From the experimental side, it is highly desirable to measure the DNA translocation process at either a constant velocity (at low velocity if possible) or constant force. Previous temperature-dependent measurements of DNA translocation through α-hemolysin pore suggest that thermal motion of DNA is a source of noise in the blockage current. There are ongoing efforts attempting to stop the translocation process while the DNA is inside the α-hemolysin pore.

Ideally, one would like to measure the ionic current while the DNA molecule is fully stretched inside the pore (e.g. using optical tweezers (see FIG. 3)). In such an experiment, fluctuations in the ionic current due to DNA thermal motion can be reduced or avoided. Also, one can hold the molecule stationary and use signal averaging to further reduce noise in the ionic current. To do this however, one needs to (a) attach a single-stranded DNA to a double-stranded DNA and then the latter to a bead (using for example streptavidin-biotin linker) held by an optical tweezers [see Introduction to Optical Tweezers; www.nbi.dk/˜tweezer/introduction.htm] and next (b) to drive the single stranded DNA through the pore and catch it from the other side using another bead (also with streptavidin-biotin linker). All these processes except optical trapping are stochastic and can be very time consuming. In order to make this idea practical, one needs to use a high-throughput device such as an array of nanopores and each pore in the array has to be addressable electrically, and independently.

Currently there are two successful methods for fabricating solid-state nanopores in insulating materials. One method involves the use of ion-beam sculpting of silicon nitride and the other uses a-beam lithography and wet etching in crystalline silicon followed by oxidation. In general these techniques have been used to validate that a nanopore can be used in the described fashion, but have not been used to yield a solid state nanopore device having high through-put.

U.S. Pat. No. 6,428,959 describes methods for determining the presence of double stranded nucleic acids in a sample. In those methods, nucleic acids present in a fluid sample are translocated through a nanopore, e.g., by application of an electric field to the fluid sample. The current amplitude through the nanopore is monitored during the translocation process and changes in the amplitude are related to the passage of single- or double-stranded molecules through the nanopore. Those methods find use in a variety of applications in which the detection of the presence of double-stranded nucleic acids in a sample is desired, e.g., in hybridization assays, such as Northern blot assays, Southern blot assays, array based hybridization assays, etc.

It would be desirable to provide a new nanopore that can be formed using synthetic material and methods for using and making such a nanopore. It also would be desirable to provide a nanopore ≦10 nm in length. It would be desirable to provide a device and method that yields a linear array of nanopores or two-dimensional array of nanopores. It also would be particularly desirable to provide such linear and 2-dimensional nanopore arrays where the nanopores are separately electrically addressable.

SUMMARY OF THE INVENTION

The present invention features devices and systems embodying one or more solid-state nanopores that can be used to sense and/or characterize single macromolecules as well as sequencing DNA or RNA. Such devices and systems have a wide range of applications in molecular biology and single-molecule biophysics. In addition to being useful for rapid DNA sequencing, the devices and systems of the present invention can be used in a variety of applications involving, but not limited to single-molecule biophysics, molecular biology, and biochemistry. For example, nanopore devices and systems of the present invention are contemplated for use as a molecular comb to probe the secondary structure of RNA molecules, for use in detecting biological warfare agents, and contaminants/pollutants in air and/or water.

According to one aspect of the present invention, there is featured a device including a member of an insulating material, wherein the insulating member is configured and arranged so as to include a through aperture comprising a nanopore therein. The through aperture comprises a plurality of crystals that have been cleaved to form atomically sharp edges, which crystals are arranged in fixed relation while forming the insulating material. In particular embodiments, the crystal edges cross each other at a predetermined angle, more particularly an angle of about 90 degrees. It is within the scope of the present invention, however, for the crystal edges to be crossed each other at an angle of less than or more than 90 degrees thereby forming nanopores having different cross-sections or different cross-sectional shapes.

The crossing cleaved crystal edges essentially form or define an area that is small enough that the molecules making up the insulating material cannot enter into this area. In this way, the molecules of the insulating material should be oriented with respect to the cleaved edges and thus forced to make a contour around the crossing point, thereby leaving a small hole comprising the through aperture therein. In a particular embodiment, the crystals are GaAs crystals that are well known in the art. However, the present invention can be practiced using other crystals known to those skilled in the art and having similar characteristics that lend themselves to being cleaved and being held in a fixed relation, while the insulating material comprising the insulating member is formed, such as for example NaCl crystals.

In a particular embodiment, the insulating material is a material that is characterized as being flowable and which solidifies at the end of the process for forming the nanopore as well as during normal operating conditions (e.g., room temperature). In an illustrative embodiment, the insulating member is made from a curable polymer such as liquid PDMS (poly-dimethylsiloxane), polystyrene or PMMA and GaAs crystals are used to form the nanopore through aperture. This technique yields a nanopore having a length or channel length of 20 Å (Angstrom/10⁻¹⁰m) or less, more particularly a channel length of 20 Å or less or more particularly a channel length of about 4 Å and more specifically a channel length (d) that satisfies one of the following relationships; 2 Å≦d≦10 Å or 4 Å≦d≦10 Å.

In the illustrative example, GaAs crystals, common semiconductor substrate materials, are cleaved to form atomically sharp edges. The cleaved crystals are then arranged so two such crystal edges are brought together to within a few angstroms distance and held fixed using standard STM electronics and use electron tunneling current as a feedback mechanism (this assumes that the GaAs crystals are doped and have finite electrical conductivity). In more particular embodiments, the spacing of the crystal edges is in the range of from between 1 Å and 10 Å, more specifically about 2 Å.

In further embodiments, the crystal edges are spaced from each other so the distance between the crystal edges is less than the thickness (Tm) of the molecule of the insulating material. In more specific embodiments, the spacing (Se) between the crystal edges is set so as to satisfy the following relationship Se/Tm≦0.5.

The curable polymer liquid PDMS (poly-dimethylsiloxane) is then poured into the region of the cutting edges and cured while the two crystal edges are held fixed. As indicated herein, at the crossing point between the two edges, the distance between the edges is so small that no molecules of the polymer can enter this region. The molecules of the polymer also are advantageously oriented parallel to the respective cleaved edges and be forced to make a contour around the crossing point, leaving a small hole. In such a methodology, the width and the length of the nanopore are controlled by the distance between the two edges and the diameter of polymers.

Following curing or formation of the insulating member in its final form, the crystals are removed, e.g., by washing, In another exemplary embodiment, the crystals used to form the through aperture are NaCl crystals, which crystals are removed by washing with H₂0.

Also featured are systems and methods utilizing the nanopore device of the present invention to perform any of a number of analytical processes including but not limited to characterizing biomolecules, sequencing DNA and determining RNA secondary structures. Such methods include providing an insulating member as hereinabove described including a nanopore, wherein a diameter and length of the nanopore are defined by the sharp edges of cleaved crystals that are maintained in fixed relation during the formation of the insulating member and locating the insulating member so as to be disposed between two ionic reservoirs. Such methods further include passing the biomolecules or DNA through the nanopore and characterizing the biomolecule or the DNA based on changes in ionic current or other physical parameter. As to the method for determining RNA secondary structures, the method further includes operably coupling one end of the RNA to an optical tweezer and measuring a force at said one end as the RNA molecule is pulled through the nanopore.

According to another aspect of the present invention there is featured an electrically-addressable nanopore array that is configured and arranged so as to allow high through-put analyses of biomolecules as well as sequencing DNA. In one particular embodiment, the electrically addressable nanopore array includes a linear or one-dimensional array of nanopores. In another embodiment, the electrically addressable nanopore array includes a two-dimensional array of nanopores. In other embodiments, the two-dimensional array is in the form of a plurality or more of linear arrays. In further embodiments the linear and two dimensional nanopore arrays are formed and arranged in the insulating material so each of the nanopores can be addressed independently using an electric current provided by, for example, a standard patch-clamp arrangement.

In particular embodiments, the electrically addressable nanopore array includes an insulating material layer. The insulating material layer is configured and arranged so as to have one or more of grooves extending lengthwise in a first direction in a first surface thereof and being parallel to each other. The insulating material layer is configured and arranged so a groove also is formed in the insulating material layer second surface that extends lengthwise in a second direction in a second surface thereof, where the first and second surfaces are opposed to each other. Also, the second direction is at an angle with respect to the first direction, more particularly the first and second directions are orthogonal to each other or at about a 90 deg. angle with respect to each other.

The grooves also are formed in each of the first and second surfaces so as to extend downwardly from one surface to the other surface, so that at an intersection of each of the grooves in the first surface and the groove in the second surface there is formed an opening that comprises a nanopore. In this way a plurality of nanopores are formed in a linear or one-dimensional array in the insulating material at the intersection of each of the plurality of grooves in the first surface and the groove formed in the second surface.

As indicated above, in further embodiments the insulating material layer is configured and arranged so as to have a plurality or more of grooves extending lengthwise in the second direction in the second first surface thereof and being parallel to each other. The plurality of grooves also are formed in the second surface so as to extend downwardly from one surface to the other surface such that at an intersection of each of the grooves in the first surface and each of the grooves in the second surface there is formed an opening that comprises a nanopore. In this way a plurality of nanopores are formed in a two-dimensional array in the insulating material at the intersection of each of the plurality of grooves in the first surface and the second surface. In more particular embodiments, the grooves are V-shaped.

In exemplary embodiments, the insulating material layer is formed from a first sub-layer and a second sub-layer that are bonded or secured to each other using any of a number of techniques known to those skilled in the art and appropriate for the materials being used so as to form the insulating material layer. The first sub-layer is configured and arranged so as to include a plurality of grooves that extend between opposing surfaces, one of the opposing surfaces comprising the first surface of the insulating material surface. Similarly, the second sub-layer is configured and arranged so as to include a groove that extends between opposing surfaces, one of the opposing surfaces comprising the second surface of the insulating material surface. In further embodiments, and as indicated herein the second sub-layer can be configured and arranged so as to include a plurality of grooves that each extend between opposing surfaces, one of the opposing surfaces comprising the second surface of the insulating material surface. When bonded or secured to each other, the first and second-sub-layers are oriented so that the first and second surfaces of the insulating material layer are opposed to each other and so that the grooves in the first sub-layer are at an angle with respect to the one or more grooves in the second sub-layer, more particularly the first and second sub-layers are oriented so that the grooves in the respective sub-layers are orthogonal to each other or at about a 90 deg. angle with respect to each other.

In specific embodiments, at least portions of the tip of each groove in the first and second sub-layer is configured and arranged so as to be open and each groove is formed in each of the first and second sub-layers so as to be separate from each other. The open portions also are arranged such that at an intersection of each of the grooves in the first sub-layer and each of the one or more grooves in the second sub-layer, there is formed an opening that comprises a nanopore. In this way a plurality of nanopores are formed in a linear or one-dimensional array in the insulating material at the intersection of each of the plurality of grooves in the first sub-layer and each groove in the second sub-layer. In more particular embodiments, the grooves are V-shaped and portions of the tips of the V-shaped grooves are formed so as to be opened.

In an exemplary, illustrative embodiment, the first and second sub-layers comprise a silicon wafer and the grooves are formed in the silicon wafer using an oxide or nitride mask in KOH solutions. Such a technique allows grooves, more particularly V-shaped grooves to be formed with high accuracy (e.g., within 20 nm) by controlling the etching rate and etching time. After the grooves are etched in the surfaces of the silicon wafers, the first and second sub-layers are bonded together. After bonding, the assemblage is oxidized to form SiO₂to insulate all silicon surfaces.

Also featured are systems and methods utilizing an electrically-addressable nanopore array of the present invention to perform any of a number of analytical processes including but not limited to characterizing biomolecules, sequencing DNA and determining RNA secondary structures. Such methods include providing an linear or two-dimensional electrically-addressable nanopore array such as that hereinabove described and locating the insulating member so as to be disposed between two ionic reservoirs. Such methods further include passing the biomolecules or DNA through any one or more of the nanopores of the linear or two-dimensional array and characterizing the biomolecule or the DNA based on changes in ionic current or other physical parameter. As to the method for determining RNA secondary structures, the method further includes operably coupling one end of the RNA to an optical tweezer and measuring a force at said one end as the RNA molecule is pulled through any one of the nanopores comprising the linear or two-dimensional array.

According to another aspect of the present invention, there is featured a PNA functionalized nanopore device as well as methods and systems related thereto. Such a PNA functionalized includes a nanopore device including one or more nanopores as herein described and a PNA coating that is applied so as to cover at least an interior surface of the at least one or more nanopores. In more particular embodiments, the PNA material is synthesized so as to be characterized or constituted by one of the bases that make up a DNA or RNA molecule. Related methods include operably coupling one end of the DNA/RNA molecule to an optical tweezer and measuring a force at said one end as the molecule is pulled through any one of the nanopores comprising the linear or two-dimensional array. The method further includes sequencing the DNA/RNA molecule by determining the fluctuations in force as a function of time and correlating the fluctuations to the bonding effect between the one basis characterizing the PNA coating and any one of the number of bases that appear in DNA or RNA.

Other aspects and embodiments of the invention are discussed below.

BRIEF DESCRIPTION OF THE DRAWING

For a fuller understanding of the nature and desired objects of the present invention, reference is made to the following detailed description taken in conjunction with the accompanying drawing figures wherein like reference character denote corresponding parts throughout the several views and wherein:

FIG. 1 illustrates the basic concept of voltage driven DNA translocation through a nanopore and more particularly (a) is a schematic of a voltage-driven DNA translocation experiment using α-hemolysin nanopore and (b) illustrates typical translocation events using poly(dA) in buffer 1 M KCl, 1 mM Tris-EDTA (pH 8.5);

FIGS. 2A,B provides histograms illustrating (FIG. 2A) the blockage current versus polymer length and (FIG. 2B) the translocation velocity versus polymer length for the same polymer;

FIG. 3 is a diagrammatic view illustrating the cutting edges mechanism for forming a nanopore using curable polymers;

FIG. 4 is a schematic view of an exemplary feedback mechanism for controlling the distance between the two cutting edges;

FIG. 5 is a three-dimensional view of a portion of the cured polymer after the GaAs crystals are removed;

FIG. 6 is a perspective view of an array of electrically-addressable nanopores according to an aspect of the present invention;

FIG. 7 is a perspective view of an electrically-addressable nanopore array device according to the present invention with a linear array of nanopores with only one groove in the upper side of the device for clarity;

FIG. 8 is a schematic view of an electrically-addressable nanopore array according to the present invention with a two-dimensional array of nanopores;

FIG. 8A is a top view with a partial cutaway of a two-dimensional array comprised of a plurality or more of the single nanopore assembly of the present invention;

FIG. 8B is a side view of the array of FIG. 8A through a single nanopore assembly;

FIG. 9 is an illustrative view illustrating holding of a molecule stationary across a nanopore using beads and optical tweezers;

FIG. 10 is a block-diagram view of an illustrative optics and video system and the general arrangement thereof with respect to an electrically-addressable nanopore array device of the present invention;

FIG. 11 is a schematic view illustrating the technique for obtaining information relating to the secondary structure(s) of RNA; and

FIGS. 12A,B are schematic views illustrating a sequencing technique using PNA functionalized nanopores according to the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring now to the various figures of the drawing wherein like reference characters refer to like parts, there is shown in FIGS. 3-5 various views to illustrate the process for making a nanopore insulating member 10, that includes a nanopore 12, according to one aspect of the present invention. More particularly, FIG. 3 is a diagrammatic view illustrating the cutting edges mechanism for forming the nanopore 12 of an insulating member 10 of the present invention using curable polymers; FIG. 4 is a schematic view of an exemplary feedback mechanism for controlling the distance between the two cutting edges of the crystals; and FIG. 5 is a three-dimensional view of a portion of the insulating member 10 after the GaAs crystals are removed.

According to one aspect of the present invention there is provided a nanoprobe insulating member 10 that is particularly configured and arranged so as to include a nanopore 12 therein that extends across a thickness of the member. In more particular embodiments, the insulating member is constructed of any of a number of insulating materials known to those skilled in that art and adaptable for use in the insulating member of the present invention. In use, the insulating nanoprobe member 10 is arranged so as to separate two reservoirs of ionic solutions, where the insulating member contains a hole, i.e., the nanopore 12 dimensioned so that that preferably only one strand of a single-stranded DNA molecule can pass there through. Also, when a voltage is applied to the two reservoirs, the electrical potential drop advantageously occurs entirely at the nanopore.

The following describes one technique for making the insulating member 10 of the present invention. However, other methods or techniques are contemplated that are adaptable to maintain crystals in fixed relation so as to provide a mechanism for defining a through aperture that comprises a nanopore. Such a methodology advantageously yields an insulating member having a nanopore whose length or channel length can be controlled so as to be about 20 Å (Angstrom/10⁻¹⁰m) or less, more particularly a channel length of about 10 Å or less or more particularly a channel length of about 4 Å and more specifically a channel length (d) that satisfies one of the following relationships; 2 Å≦d≦10 Å or 4 Å≦d≦10 Å. As indicated herein, conventional techniques for forming nanopores for such use, result in a structure in which the nanopore has a length in excess of the length of the DNA strand to be characterized which can lead to inaccuracies in the characterization.

As illustration of this technique, crystals are cleaved to form atomically sharp edges and two of these cleaved crystals are brought together within a few angstroms distance of each other. In addition, the crystals are arranged so the crystal edges are cutting each other at an angle of about 90 degrees, as shown in the diagram in FIG. 3. The two crystals are held in fixed relation using standard STM (scanning tunneling microscope) electronics such as that shown in FIG. 4 and using the electron tunneling current as a feedback mechanism. At the crossing point between the two edges, the distance between the edges is so small that no molecules larger than a certain size can enter into this region. Stated another way, the crossing point is established such that molecules having a width greater than a desired width cannot enter into this region. In more particular embodiments, the edges of the crystals are spaced from each other so as be in the range of from between 1 Å and 10 Å, more specifically about 2 Å. In further embodiments, the crystal edges are spaced from each other so the distance between the crystal edges is less than the thickness (Tm) of the molecule of the insulating material. In more specific embodiments, the spacing (Se) between the crystal edges is set so as to satisfy the relationship Se/Tm≦0.5.

The crystals contemplated for use in the present invention include a wide range of crystals and in a particular, exemplary illustrative embodiment the crystals include GaAs crystals, a common semiconductor material, and NaCl crystals. However, the present invention can be practiced using other crystals known to those skilled in the art and having similar characteristics that lend themselves to being cleaved and being held in a fixed relation while the insulating material comprising the insulating member is being formed.

The crystals when so arranged use the crossing cleaved crystal edges as a mold (e.g., nano-molding). After arranging the crystals in fixed relation to one another an insulating material (e.g., a flowable insulating material), such as a curable polymer liquid PDMS (poly-dimethylsiloxane), is poured into the region of the cutting edges and allowed to cure while the two crystal edges are held fixed. The distance between the edges is set to be so small that no molecules can enter this forbidden region. Thus, molecules comprising the insulating material making up the insulating member 10 are prevented from gaining access into the so-called forbidden region. One possible molecular conformation of the polymers near the crossing point also is shown in FIG. 3. The molecules of the insulating material are advantageously oriented parallel to the respective cleaved edges and are forced to make a contour around the crossing point, leaving a small hole of a given width and length. The width and the length of the small hole are controlled by the distance between the two edges and the diameter of the insulating material (e.g., polymers).

In further embodiments, and after the insulating member 10 is so-formed, the crystals that were used to controllably form the nanopore or opening in the insulating member are removed using any of a number of techniques known to those skilled in the art that do not appreciably effect the insulating material about the formed hole, e.g., in the case of NaCl crystals, by washing with water. Following removal of the crystals, an opening is formed in the member such as that illustrated in FIG. 5, having a desired width and length. Because the chemical groups (nucleotides) of a DNA molecule have slightly different sizes, one can identify the nucleotides of a DNA molecule, and hence sequence the DNA molecule, by measuring the time dependence of the nanopore conductance. In this way, a nanopore is formed in the insulating material; having a desired width and length for purposes of characterizing the biomolecules, more particularly fast characterization of the biomolecule. Such an insulating member 10 is thus of great utility for a wide range of uses including forensics, rapid sequencing of DNA and research. As indicated herein, the amount of the conductance drop will be a measure of the physical size of the part of the DNA molecule that is inside the narrowest part of the channel.

Referring now to FIG. 6, there is shown a perspective view of device 100 including an array of electrically-addressable nanopores 112, more particularly a linear array of nanopores according to another aspect of the present invention. The device 100 includes an insulating member 110 having a top surface 112 and a bottom surface 114. A plurality of grooves 116 are formed in the top surface using any of a number of techniques known to those skilled in the art that are appropriate for the material comprising the insulating member. The grooves 116 in the top surface 112 are formed in the insulating member 110 so as to generally extend downwardly towards the bottom surface 114 a predetermined distance from the top surface. Correspondingly, the groove 118 in the bottom surface 114 is formed in the insulating member 110 so as to generally extend upwardly towards the top surface 112 a predetermined distance from the bottom surface.

In addition, at the points of intersection between the grooves 116 in the top surface 112 and the groove 118 in the bottom surface 114, the insulating member is configured and arranged so an opening or nanopore 122 is provided in the insulating member 110 so as to fluidly couple each of the top surface grooves 116 with the bottom surface groove 118. The formation of the grooves 116, 118 and the nanopores 122 are discussed in more detail hereinafter.

In more particular embodiments, the insulating member 110 includes a first layer 120a and a second layer 120b that are bonded or otherwise secured to each other using any of a number of techniques known to those skilled in the art appropriate for the material being used to form the insulating member. In this particular embodiment, the top surface grooves 116 are contained in the first layer 120 and the bottom surface groove is contained in the second layer.

The nanopores 122 are formed in the insulating member or each of the first and second layers using any of a number of techniques appropriate for the material being used and appropriate for forming a nanopore having the desired width and length for e.g., rapidly characterizing a biomolecule. In one particular embodiment, the first and second layers 120a,b are bonded or secured together and the nanopores 116 are formed at the intersections of the top and bottom surface grooves 116, 118. In another particular embodiment, portions of the tips of the top and bottom surface grooves 116, 118 are formed so as to included an opening in each groove proximal the point of intersection such that when the first and second layers 120a,b are bonded or secured together the sharp edge openings in the grooves are aligned so as to form a nanopore.

In addition, in the illustrated embodiment, the grooves 116, 118 are formed in the top and bottom surfaces 112,114 so as to provide deep V-shaped grooves. This shall not be limiting as other shapes as are known to those skilled in the art that are otherwise adaptable and consistent with the function of the grooves in the present invention are contemplated for use in the present invention.

In a particularly illustrative embodiment, the insulating member 110 and the first and second layers are initially formed from a silicon material, which is subsequently oxidized after further processing of the insulating member to form SiO₂, an insulating material. Although, the starting material is silicon, this shall not be considered limiting as other materials are contemplated for use with the present invention that would allow creation of the linear array of nanopores 122 as herein described using techniques that are appropriate for the material of use.

More specifically, the silicon material is subjected to micromachining techniques as are known to those skilled in the art to form the grooves 116, 188 and the nanopores 122. In particular, the grooves and the nanopores are etched in the silicon wafer using an oxide or nitride mask, in KOH solutions with relatively high accuracy, or by use of beam lithography and wet etching techniques. It has been found that conventional or standard wet etching procedures as known in the art can produce highly uniform grooves as is illustrated in FIG. 6.

In further embodiments, the silicon wafers making up the first and second layers 120a,b are bonded or secured together and then material at the intersections of the top surface grooves 116 and the bottom surface groove 118 the tips of the grooves are further etched using a similar process to that used to form the grooves to form an opening there through. In yet another embodiment, during the formation of the grooves 116, 118, portions of the tips or valleys of the grooves, in particular the portions proximal the intersections of the top and bottom surface grooves, are further etched so as to form an opening in these portions of the tips. The first and second layers are the bonded or secured to each other and the sharp edges of the openings form the nanopores at the intersections. In this way, “cutting-edges” pores are yielded, one by bonding two silicon wafers with the sharp edges of the grooves facing each other at 90°, and the other by directly etching from one or both sides of the silicon wafers with grooves at 90° relative to each other. As is known to those skilled in the art, the etching of the surfaces can be accurately controlled by controlling the etching rate and etching time. Following such etching and bonding of the silicon wafers or material forming the first and second layers 120a,b, the assemblage is then oxidized to form SiO2 to insulate all silicon surfaces, thereby forming the insulating member in its operable form.

In further embodiments, and after making the insulating member 110 so as to be in its operable form, the nanopores 122 are further examined using for example an electron microscope to determine if the nanopores that are formed have the desired width. If not, and assuming that the width of a given nanopore is less than a critical width, the nanopore is exposed to a high-energy electron beam to modify the dimensions of the nanopore. As more fully describe below, small holes shrink spontaneously due to surface tension when exposed to the electron beam and when the electron beam is switched off, the material quenches and retains its shape.

The following further illustrates this modification process using for example, a commercial transmission electron microscope (TEM), operated at an accelerating voltage of 300 kV. It is well known in electron microscopy that a high electron intensity can damage or deform the specimen, and in general one tries to minimize this effect. However, in the present invention this effect is used to modify the dimensions of the silicon oxide nanopores in a controlled fashion. It has been found that an electron intensity around 10⁶to 10⁷A/m²causes pores to shrink if the pore has an initial diameter about 50 nm or lower.

The power of this technique lies in the possibility to fine-tune the diameter of nanopores with unprecedented precision. By lowering the beam intensity or blanking it, the shrinking process can be stopped within seconds when the desired diameter has been reached. In addition, changes in pore diameter can be monitored in real time using the imaging mechanism of the microscope. Rough shrinking can be done at least an order of magnitude faster by increasing the electron intensity, and can gradually be slowed down for ultimate control. The precision is ultimately limited by the resolution of the microscope. In practice the resolution is limited to about 1 nm due to the surface roughness of the silicon oxide. The level of control offered by this technique is at least an order of magnitude better than conventional e-beam lithography, which has an ultimate resolution of about 10 nm. As such, this use of this modification technique provides a mechanism to reduce the required dimensional control in the lithographic process for forming the grooves and nanopores, because any pore with a diameter below 50 nm can be shrunk to a nanometer-sized pore.

The physics attendant with the growing and shrinking that has been observed using the above electron beam process is determined by the surface tension of the viscous silicon oxide. In this state, the structure will deform to find a configuration with a lower free energy F. Simple free-energy consideration suggest that the surface energy of pores with radius r<½h can be lowered by reducing r, and that the surface energy for pores with radius r>½h can be increased by increasing size. The “critical diameter” discriminating the two cases is of order of the thickness of the silicon, with the exact ratio depending on the geometry of the pore. This scaling argument is valid at any scale, and explains elegantly the observed dynamics in our pores.

The advantage of this technique of the present invention is that nanometer-scale sample modifications are possible with direct-visual feedback at sub-nanometer resolution. The process is based on standard silicon processing and commercially available TEM microscopy. A modest resolution of <50 nm is required in the lithography defining the pore, as fine tuning in the electron beam is done as a final step. Using the SOI based process, this requirement is straightforward to obtain with e-beam lithography, and should be attainable even with optical lithography alone. Other advantages of the techniques of the present invention compared to recently reported “ion beam sculpting” techniques are that the technique of the present invention does not change the chemical composition of the material surrounding the pore because the electron beam softens the glassy silicon oxide, allowing it to deform and be slowly driven by the surface tension. The electron microscope also provides real time visual feedback, and when the desired morphology has been obtained the electron beam intensity is lowered and the SiO₂is quenched to its initial glassy state.

Referring now to FIG. 8 there is shown a schematic view of an electrically-addressable nanopore array 200 according to the present invention configured with a two-dimensional array of nanopores 116. In the illustrated embodiment shown in FIG. 6, the two dimensional array is made up of two or more sets of linear arrays that are formed on a single insulating member 110. In the illustrated embodiment, the grooves 116a,b in the top surface are formed so there is one set of grooves 116a for one of the linear arrays and so there is another set of grooves 116b for each of the other linear arrays. In further embodiments, the grooves 116a,b in the top surface 112 or the first layer 120a are formed so the grooves for each linear array are separate from or not connected to the grooves of another linear array. For example, when the grooves are being etched in the top surface of a silicon wafer, material is not advantageously removed from the top surface between the ends of the grooves.

The foregoing shall not be considered as limiting as it is within the scope of the present invention for the grooves 116 in the top surface of a two-dimensional array according to the present invention to be configurable so that the grooves in the top surface are interconnected, thereby forming a single set of top surface grooves. For example, in cases where the ionic current is not crucial to analysis or characterization, such as for analysis of RNA secondary structures as described below, the two-dimensional array can be configured so that the grooves in the top surface are interconnected to form a single set of grooves.

Referring now to FIG. 7 there is shown a perspective view of an electrically-addressable nanopore array device 300 according to the present invention including an electrically-addressable nanopore array 100 further including a linear array of nanopores 122. For clarity, only one top surface groove 116 is shown or illustrated. However, this shall not be considered as limiting, as the linear array 100 can include a plurality or more, for example 100 top surface grooves thereby forming 100 nanopores. Further, and although a linear array is illustrated, it is within the scope of the present invention for the device to include a two-dimensional array 200 including the array shown in FIG. 8.

In the foregoing discussion, reference shall be made to the FIGS. 6 and 8 that illustrate further details of the electrically-addressable arrays 100, 200 contemplated for use with an electrically-addressable nanopore array device 300 of the present invention. Also, the electrodes and fluid ports are shown for illustration purposes. In an actual device the electrodes and the fluid ports are sealed.

An electrically-addressable nanopore array device 300 according to the present invention includes cover slips 302 as are known to those skilled in the art, that seal the top and bottom surfaces of the array. Following fabrication of the electrically-addressable nanopore array 100, the cover slips 302 are secured or bonded to the top and bottom surfaces thereof using any of a number of techniques known to those skilled in the art appropriate for the materials being used. This is preferably done after the electrically-addressable nanopore array 100, 200 is determined to be in operable condition (e.g., nanopores of the desired width and length appropriate for the particular analytical technique). In addition, the electrically-addressable nanopore array device 300 is appropriately arranged with pumping lines and electrodes (e.g., Ag/AgCl wires) as is known to those skilled in the art. As is known to those skilled in the art other devices, apparatuses and systems (not shown) are interconnected to the electrically-addressable nanopore array device 300 for purposes of supplying samples for analysis, for collection of data and for the analysis of the collected data.

Referring now to FIGS. 8A,B there is shown various views of a two-dimensional nanopore array 500 according to another aspect of the present invention. The two-dimensional array 500 according to this aspect of the present invention, and with reference to FIG. 8A, comprises a plurality or more of single nanopore assemblies 510 of the present invention each including a nanopore 512 preferably formed using one of the techniques described herein. There is more particularly shown in FIG. 8A a top view, with a partial cutaway, of a two-dimensional array 500 of this aspect of the present invention and there is shown in FIG. 8B a side view of the array of FIG. 8A through a single nanopore assembly. Reference shall be made to the foregoing discussion regarding FIGS. 3-5 as to the techniques for making a nanopore assembly 512 according to the present invention having the desired characteristics. Reference also should be made to the foregoing discussion for FIG. 7 as to further details, features and characteristics of electrically addressable nanopore arrays not described below. In addition to the nanopore assemblies 510, the two-dimensional nanopore array 500 includes a top member 520 and a bottom member 530.

The nanopore assemblies 510 are configured and arranged in the two-dimensional array 500 such that the first volume 514 for each nanopore assembly is separate and electrically isolatable from each other. The top member 520 is affixed or secured to atop surface(s) of each of the nanopore assemblies 510 in such a fashion so as to also maintain the first volume 514 of each nanopore assembly separate and electrically isolatable from each other. The top member 520 further includes a plurality or more of through apertures 522 that are arranged in the top member so that there is one aperture in fluid communication with the first volume 514 of each nanopore assembly 510.

Similarly, the bottom member 530 is secured to a lower surface(s) of each nanopore assembly 510 so a passage 516 in each nanopore assembly and the bottom member defines one or more volumes for receiving the material that has passed through a nanopore 512 such that the passed through material can be appropriately handled or processed further.

The top and bottom members 520, 530 are made from any of a number of materials known to those skilled in the art that are appropriate for the intended use and being securable to the surface(s) of the nanopore assemblies (e.g., such as the cover slips 320 herein described). The through apertures 522 in the top member 520 are formed therein using any of a number of techniques known to those skilled in the art. The size and depth of such through apertures 522 are such as to allow material to easily pass there through into the first volume 514, and minimizing the potential for damage to the material as it passes through the through aperture. It should be recognized that the size or diameter of the through apertures 522 need not be set so as to meet the same desired characteristics for a nanopore 512.

Such an arrangement and configuration yields a two-dimensional nanopore array 500 in which each nanopore 512 is separately, electrically addressable from any other of the nanopores making up the array. Thus, material to be analyzed, processed and/or evaluated can be introduced into each of the nanopores 512 so the material (e.g., DNA) passing though any one nanopore can be uniquely or separately identified, characterized, analyzed, processed or evaluated. Such a two-dimensional array 500 exhibits a high through put yet maintains the capability for providing details, characteristics or features of the material passing through each of the nanopores 512.

The nanopore assemblies 510 also are immobilized using any of a number of techniques known to those skilled in the art, including but not limited to mechanical and adhesive securing techniques, so the assemblage of the nanopore assemblies in effect forms a unitary structure. For example, the nanopore assemblies can be secured to each other using an adhesive material. In more particular embodiments, the top member 520 the bottom member 530 and the nanopore assemblies 510 are secured to each other so as to form a unitary structure.

In the illustrated embodiment, the two-dimensional array 500 is made up of a 4×4 matrix of nanopores 512 or nanopore assemblies 510. This shall not constitute a limitation, as it is within the scope of the present invention for the array to be composed of more or less nanopores or nanopore assemblies. For example a two-dimensional array 500 according to the present invention can be made up of 1000 or more nanopores 512 or a 1000 or less nanopore 512 (e.g., an array comprising a matrix of 100×100 nanopores). Also while a square array is illustrated (e.g., same number of nanopores 512 in x and y directions) this shall not constitute a limitation as it is within the scope of the present invention for the nanopore assemblies to be arranged so the number of nanopores along one axis differs from the number of nanopores along the other axis (e.g., 100×75 array of nanopores). It also is contemplated that the nanopore assemblies are arrangeable so the number of nanopores 512 varies along one axis (e.g., varies between 100 and 70 nanopores) and so the number of nanopores along the other axis generally differs from those along the one axis (e.g., 75 nanopores).

Although the foregoing describes a two-dimensional array 500 comprising a plurality or more, more particularly a large number of nanopore assemblies 512, it is within the scope of the present invention using the herein described techniques for processing a silicon wafer, to form a two-dimensional array of nanopores that each are fluidly coupled to a first volume formed in the silicon wafer and so that each first volume is separated from each other so that each nanopore is separately, electrically addressable.

As indicated herein, a process for rapid DNA sequencing using the ionic current have not been realized as yet, nor has this process been useable to distinguish between adenine and guanine and between cytosine and thiamine. Recent attempts using α-hemolysin protein nanopore to discriminate the nucleotides within the purine (adenine and guanine) and pyrimidine (cytosine, thiamine, and uracil) groups also have not been successful. However, the disadvantages of prior art processes are overcome by the devices of the present invention. For example, in one embodiment the electrically-addressable nanopore array device 300 of the present invention is further configured and arranged so as to reduce signal noise believed to be attributable to thermal motion of DNA as it passes through the nanopore. More particularly, the electrically-addressable nanopore array device 300 is configured and arranged with an objective lens 320 on either side of the array device, so as to form two optical traps or two optical tweezers to hold the DNA molecule stationary across a nanopore 122. In this way, noise in the ionic current signal being caused by the wiggling motion of the DNA molecule near and/or in the nanopore should be greatly reduced. Also by holding the molecule stationary, signal-averaging techniques can be used to further reduce noise in the ionic current.

Holding the molecule stationary can be best understood from the following illustrative example, although it well within the skill of those in the art to apply and adapt other techniques that are more appropriate for the items undergoing analysis/characterization. A single-stranded DNA is attached to a double stranded DNA and then the latter is attached to a bead 400 using a streptaviding-biotin linker, which bead is to be held by optical tweezers. Next the single-stranded DNA is driven through the nanopore 122 and caught from the other side using another bead 400 also with a streptaviding-biotin linker, which also is held by optical tweezers. The holding of the molecule stationary across the nanopore 122 using beads 400 is shown illustratively in FIG. 9. In an illustrative embodiment, the beads 400 or microspheres are polystyrene micropsheres or beads.

There is shown in FIG. 10 an illustrative optics and video system 500 and the general arrangement of the components thereof with respect to the electrically-addressable nanopore array device 300 (EANA in figure) of the present invention. Such an optical and video system 500 is equipped with optical tweezers and a digital video microscopy system that is based on a Zeiss Axiovert 135 inverted microscope. In further embodiments, the illustrated Argon ion laser can be replaced by a semiconductor-based infra-red laser, to minimize light damage to the biomolecules on the microspheres. The system includes two objectives, and the condenser in the standard optical microscope is replaced by a 100× oil-immersion objective. Also, illumination of the sample can be accomplished using a de-focused diode light source through the objectives.

As is generally known to in the art, a subfield within laser physics is optical trapping and an optical tweezer is an example of an optical trap. A strongly focused laser beam has the ability to catch and hold particles (e.g., particles of dielectric materials) in a predetermined size range. This technique makes it possible to study and manipulate particles like atoms and molecules (even large) and small dielectric spheres. A review on uses of optical tweezers can be found in A. Ashkin “Optical trapping and manipulation of neutral particles using lasers”, Proc. Natl. Acad. Sci. USA, vol. 94, pp. 4853-4860, May 1997.

As is known in the art, a long (single-stranded) RNA (ribonucleic acid) molecule can partially fold onto itself, forming secondary structures, due to local pairing of complementary bases. It is believed that these secondary structures of RNA are more important for the properties of the molecules than their primary sequences. For example, the diverse functions of RNA molecules in cells, from messenger RNA (mRNA) that carries the genetic information from DNA (deoxyribonucleic acid) to protein synthesis, to transfer RNA (tRNA) that carries amino acids to ribosomes during translation, arise largely from their secondary structures. Developing a physical technique for fast determination of RNA secondary structures is a major goal of the emerging field of single molecule biophysics.

In the present invention, buffers containing RNA attached microspheres or beads 400 are flushed through the lower surface groove 118, while the nanopores 122 are biased by an electric field. Occasionally an RNA molecule is pulled through a nanopore 122 by the electric field. One can identify this event by looking for a localized microsphere or bead 400 near a pore. Then, the electrical field is turned off to allow the RNA to form secondary structures. Now, and also with reference to FIG. 11, the microsphere or bead 400 is slowly pulled away using optical tweezers and the force on the bead is measured as the RNA molecule is pulled (upward) through the nanopore 122. The sequential breakage of the RNA base pairs at the entrance of the nanopore 122 will appear as force fluctuations as a function of time, hence revealing the information about the secondary structure of the test molecule. It should be noted that this situation is quite different from the previous RNA pulling experiments in which the RNA was pulled from the two ends, where without the prior knowledge of the secondary structure of an RNA, it would be difficult to assign the features in a force vs. time trace. The present invention does not require prior knowledge of the secondary structure of an RNA molecule.

Referring now to FIGS. 12A,B there is shown schematically another technique for characterizing (e.g., sequencing) DNA or RNA using nanopores or nanopore arrays of the present invention. More particularly these schematic views illustrate a sequencing technique using PNA functionalized nanopores 600 according to the present invention. Reference shall be made to the foregoing discussion for the various techniques and arrangements for providing a nanopore device, apparatus or assemblage according to the present invention without PNA. For clarity, the following discussion and figures illustrate the technique and device of the present invention by referring to a single nanopore. It is within the scope of the present invention, however, for the below described technique and device to be adapted for use with a plurality or more of nanopores that are arranged so as to form a linear array or a two-dimensional array.

After forming a nanopore 602, peptide nucleic acid (PNA) is applied so as to coat at least a portion of the nanopore, for example at least the interior surface of the nanopore 602 so as to form a PNA coating 604. The PNA coating 604 and the nanopore 602 so coated is herein referred to as PNA functionalized nanopore 600. The PNA coating 604 on the nanopore is exposed to any DNA/ RNA passing through the opening 606 in the PNA functionalized nanopore 600. In particular embodiments, the PNA is synthesized so that it is essentially constituted by one of the bases of DNA or RNA (e.g., adenosine, thymidine, guanine, cytosine, uracil). More specifically the PNA is synthesized so that the one basis characterizing or constituting the PNA is set so as to have a noticeable effect on the passage of the DNA/RNA through the PNA functionalized nanopore 600, and more particularly different effects depending upon the different bases that can make up the DNA/RNA.

As illustration and with particular reference to FIG. 12B, the PNA coating 604 is such as to be constituted or characterized as having essentially only adenosine bases (hereinafter referred to as A-PNA). Consequently, the A-PNA will have differing effects (e.g., hydrogen bonding) on the passage of a strand of DNA/RNA through the functionalized nanopore 600 depending upon the particular bases constituting the DNA and the sequence of the bases in the DNA/RNA as well as the distance (e.g., bonding distance) between the PNA coating 604 and the DNA/RNA strand. For example, there is a strong bonding effect between A and T bases, consequently a comparatively large force is applied upon the DNA/RNA strand thereby retarding movement of the strand within the functionalized nanopore 600.

Using techniques known to those skilled in the art such as those described herein, the force retarding movement or other related parameter (e.g., time to move a given distance) is determined or detected and the detected/determined parameter is evaluated to determine if the parameter corresponds to that which would be exhibited if the A-PNA is bonding to a T, A, G or C bases of the DNA. In one illustrative technique, an end of the DNA/RNA strand is driven through the PNA functionalized nanopore 600 and caught from the other side using a bead 400 with a streptaviding-biotin linker. Optical tweezers as is known in the art are used to hold the bead 400. In a further illustrative embodiment, the beads 400 or microspheres are polystyrene micropsheres or beads.

The microsphere or bead 400 is slowly pulled away from the PNA functionalized nanopore 600 using optical tweezers and the force on the bead is measured as the DNA/RNA molecule is pulled through the functionalized nanopore. As indicated herein, the bases making up the DNA/RNA molecule will cause differing forces to be applied to the molecule affecting the movement of the molecule through the fictionalized nanopore 600. These different effects will appear as force fluctuations as a function of time, hence revealing the information at least about the sequence of the A, T, G, C bases making up the test molecule.

Although a preferred embodiment of the invention has been described using specific terms, such description is for illustrative purposes only, and it is to be understood that changes and variations may be made without departing from the spirit or scope of the following claims.

Incorporation by Reference

All patents, published patent applications and other references disclosed herein are hereby expressly incorporated by reference in their entireties by reference.

Equivalents

Those skilled in the art will recognize, or be able to ascertain using no more than routine experimentation, many equivalents of the specific embodiments of the invention described herein. Such equivalents are intended to be encompassed by the following claims.

Claims

1. A device for characterizing biomolecules, comprising:

an insulating member, the insulating member including a through aperture extending between opposing surfaces; and

wherein a width of the through aperture is established by a plurality of crystals that are arranged in fixed relation with respect to each other while forming the insulating member.

2. The device of claim 1, wherein edges of the plurality of crystals cross each other at a predetermined angles and are maintained in this arrangement while forming the insulating member.

3. The device of claim 2, wherein the edges form or define an area that is small enough that the molecules making up the insulating member cannot enter into this area while forming the insulating member.

4. The device of claim 2, wherein molecules of insulating material are oriented with respect to the edges thereby forcing the insulating material to form a contour around the crossing point thereby defining the through aperture in the insulating member.

5. A method for characterizing a biomolecule comprising the steps of:

providing an insulating member, the insulating member including a through aperture extending between opposing surfaces and wherein a width of the through aperture is established by a plurality of crystals that are arranged in fixed relation with respect to each other while forming the insulating member;

locating the insulating member between ionic reservoirs at least one of which includes the biomolecule to be characterized; and

passing the biomolecule through the through aperture of the provided insulating member.

6. The method of clam 5, further comprising the step of:

detecting an ionic current and changes in ionic current as the biomolecule is passed through the through aperture; and

characterizing the biomolecule based on the detected ionic current and changes thereto.

7. A method for determining RNA secondary structures comprising the steps of:

providing an insulating member, the insulating member including a through aperture extending between opposing surfaces and wherein a width of the through aperture is established by a plurality of crystals that are arranged in fixed relation with respect to each other while forming the insulating member;

locating the insulating member between ionic reservoirs at least one of which includes the biomolecule to be characterized;

operably coupling coupling one end of the RNA to an optical tweezer; and

measuring a force at said one end as the RNA molecule is pulled through the through aperture.

8. An electrically-addressable nanopore array comprising:

an insulating material member;

wherein the insulating material layer is configured and arranged so as to have a plurality or more of grooves extending lengthwise in a first direction in a first surface thereof;

wherein the insulating material member is configured and arranged so as to have a groove extending lengthwise in a second direction in a second surface thereof, the first and second surfaces being opposed to each other;

wherein the second direction is at an angle with respect to the first direction; and

wherein the grooves are formed in each of the first and second surfaces so that at an intersection of each off the grooves in the first surface and the groove in the second surface there is formed an opening that comprises a nanopore.

9. The electrically-addressable nanopore array of claim 8, wherein the insulating material members is formed from a first layer and a second layer, where a surface of the first layer is the first surface of the insulating material member, where the first layer includes the plurality of grooves formed in the insulating member first surface, where a surface of the second layer is the second surface of the insulating material member and where the second layer includes the groove formed in the insulating member second surface.

10. The electrically-addressable nanopore array of claim 9, wherein the first and second layers are one of bounded or secured to each so as to form the insulating material member.

11. The electrically-addressable nanopore array of claim 8, wherein the insulating material member is configured and arranged so as to have a plurality of grooves extending lengthwise in a second direction in the second surface thereof.

12. The electrically-addressable nanopore array of claim 11, wherein the insulating material layer is configured and arranged so as to have a plurality of sets of a plurality or more of grooves extending lengthwise in a first direction in a first surface thereof, where the grooves in each set are not connected to grooves in another set.

13. The electrically-addressable nanopore array of claim 12, wherein the grooves are formed in each of the first and second surfaces so that at an intersection of each off the grooves in the first surface of each set of grooves and one of the plurality of grooves in the second surface there is formed an opening that comprises a nanopore.

14. A method for characterizing a biomolecule comprising the steps of:

providing an electrically-addressable nanopore array including an insulating material member, wherein the insulating material member is configured and arranged so as to have a plurality or more of grooves extending lengthwise in a first direction in a first surface thereof and a groove extending lengthwise in a second direction in a second surface thereof, the second direction is at an angle with respect to the first direction, and wherein the grooves are formed in each of the first and second surfaces so that at an intersection of each off the grooves in the first surface and the groove in the second surface there is formed an opening that comprises a nanopore;

locating the electrically-addressable nanopore array between ionic reservoirs at least one of which includes the biomolecule to be characterized; and

passing the biomolecule through one of the nanopores of the provided electrically-addressable nanopore array.

15. The method of clam 14, further comprising the step of:

detecting an ionic current and changes in ionic current as the biomolecule is passed through the one the nanopores; and

characterizing the biomolecule based on the detected ionic current and changes thereto.

16. A method for determining RNA secondary structures comprising the steps of:

providing an electrically-addressable nanopore array including an insulating material member, wherein the insulating material member is configured and arranged so as to have a plurality or more of grooves extending lengthwise in a first direction in a first surface thereof and a groove extending lengthwise in a second direction in a second surface thereof, the second direction is at an angle with respect to the first direction, and wherein the grooves are formed in each of the first and second surfaces so that at an intersection of each off the grooves in the first surface and the groove in the second surface there is formed an opening that comprises a nanopore;

locating the electrically-addressable nanopore array between ionic reservoirs at least one of which includes the biomolecule to be characterized;

operably coupling coupling one end of the RNA to an optical tweezer; and

measuring a force at said one end as said the RNA molecule is pulled through one of the nanopores.

17. A nanopore comprising:

an insulating member having opposed surfaces; and

a through aperture extending between said opposing surfaces.

18. The nanopore of claim 17, wherein the width of said through aperture is less than about 10 nm.

19. A nanopore array comprising a plurality of nanopores, wherein each nanopore comprises:

an insulating member having opposed surface; and

a through aperture extending between said opposing surfaces.

20. The nanopore array of claim 19, wherein said through aperture has a width that is less than about 10 nm.

21. The nanopore array of claim 19, wherein each of said nanopores is electronically addressable.

22. A method for preparing a nanopore comprising an insulating member having opposed surfaces and a through aperture extending between said surfaces, the method comprising the steps of:

forming an aperture having a width that is established by fixing a plurality of crystals fixed in position to one another;

forming an insulating member by casting an insulating material over said plurality of crystals fixed in position relative to one another, thereby forming the insulating material with said aperture extending through opposing surfaces of said insulating material; and

removing said plurality of crystals,

to thereby prepare a nanopore comprising an insulating member having opposed surfaces and a through aperture extending between said surfaces.

23. A nanopore comprising an insulating member having opposed surfaces and a through aperture extending between said surfaces, said nanopore having been prepared by a method comprising the steps of:

forming an aperture having a width that is established by fixing a plurality of crystals fixed in position to one another;

forming an insulating member by casting an insulating material over said plurality of crystals fixed in position relative to one another, thereby forming the insulating material with said aperture extending through opposing surfaces of said insulating material; and

removing said plurality of crystals,

to thereby prepare a nanopore comprising an insulating member having opposed surfaces and a through aperture extending between said surfaces.

24. A method for preparing a nanopore array comprising an insulating member having opposed first and seconds surfaces and one or more through apertures extending between said surfaces, the method comprising the steps of:

forming one or more grooves in the first surface that extend lengthwise in a first direction;

forming one or more grooves in the second surface that extend lengthwise in a first direction, the second direction being at an angle with respect to the first direction;

removing material at intersections of the one or more grooves in the first surface and the one or more grooves in the second surface;

to thereby prepare a nanopore comprising an insulating member having opposed surfaces and a one or more through aperture extending between said surfaces.

25. The device of claim 2, wherein the edges of the crystals are spaced from each other a distance (Se) and the crystal distance spacing is set so as to satisfy (Se/Tm)≦0.5 where Tm is a thickness of a molecule of the material making up the insulating member.

26. The device of claim 2, wherein the edges of the crystals are spaced from each other a distance (Se) and the crystal distance spacing is set so as to be in the range of from about 1 Å to about 10 Å.

27. The device of claim 1, wherein the through aperture has a length less than or equal 20 Å.

28. The device of claim 1, wherein the through aperture has a length (d) that satisfies the relation 2 Å≦d≦10 Å.

29. The method of claim 5, wherein the through aperture of the provided insulating member has a length less than or equal 20 Å.

30. The method of claim 1, wherein the through aperture of the provided insulating member has a length (d) that satisfies the relation 2 Å≦d≦10 Å.

31. The method of claim 5, wherein the edges of the crystals are spaced from each other a distance (Se) and the crystal distance spacing is set so as to satisfy (Se/Tm)≦0.5 where Tm is a thickness of a molecule of the material making up the insulating member.

32. The method of claim 5, wherein the edges of the crystals are spaced from each other a distance (Se) and the crystal distance spacing is set so as to be in the range of from about 1 Å to about 10 Å.

33. The method of claim 7, wherein the through aperture of the provided insulating member has a length less than or equal 20 Å.

34. The method of claim 7, wherein the through aperture of the provided insulating member has a length (d) that satisfies the relation 2 Å≦d≦10 Å.

35. The method of claim 7, wherein the edges of the crystals are spaced from each other a distance (Se) and the crystal distance spacing is set so as to satisfy (Se/Tm)≦0.5 where Tm is a thickness of a molecule of the material making up the insulating member.

36. The method of claim 7, wherein the edges of the crystals are spaced from each other a distance (Se) and the crystal distance spacing is set so as to be in the range of from about 1 Å to about 10 Å.

37. A method for preparing a two-dimensional nanopore array comprising an insulating member having opposed surfaces and a plurality of through aperture extending between said surfaces, the method comprising the steps of:

forming each of the plurality of apertures having a width that is established by fixing a plurality of crystals fixed in position to one another for each aperture;

forming an insulating member by casting an insulating material over each of said plurality of crystals fixed in position relative to one another for each aperture, thereby forming the insulating material with said each aperture extending through opposing surfaces of said insulating material; and

removing said plurality of crystals for each aperture,

to thereby prepare a two-dimensional nanopore array comprising an insulating member having opposed surfaces and a plurality of through apertures extending between said surfaces.

38. A method for preparing a nanopore array comprising the steps of:

providing a plurality of nanopore assemblies, each of the plurality of nanopore assemblies including an insulating member having opposed surfaces and a through aperture extending between said surfaces,

assembling the plurality of nanopore assemblies so the through apertures form at least a one-dimensional array of through apertures; and

wherein said providing a plurality of nanopore assemblies includes performing the steps of for each nanopore assembly: forming an aperture having a width that is established by fixing a plurality of crystals fixed in position to one another, forming an insulating member by casting an insulating material over said plurality of crystals fixed in position relative to one another, thereby forming the insulating material with said aperture extending through opposing surfaces of said insulating material, and removing said plurality of crystals, to thereby prepare a nanopore comprising an insulating member having opposed surfaces and a through aperture extending between said surfaces.

39. The method of claim 38, wherein said assembling the plurality of nanopore assemblies includes assembling the plurality of nanopore assemblies so the through apertures form a two-dimensional array of through apertures.

40. The method of any of claims 38-39, wherein the through aperture of each of the plurality of provided nanopore assemblies has a length less than or equal 20 Å.

41. The method of any of claims 38-39, wherein the through aperture of each of the plurality of provided nanopore assemblies has a length (d) that satisfies the relation 2 Å≦d≦10 Å.

42. The method of any of claims 38-39, wherein said forming an aperture includes spacing edges of the crystals from each other a distance (Se), where the distance is set so as to satisfy the relation (Se/Tm)≦0.5 where Tm is a thickness of a molecule of the material making up the insulating member.

43. The method of any of claims 38-39, wherein said forming an aperture includes spacing edges of the crystals from each other a distance (Se), where the distance is set so as to be in the range of from about 1 Å to about 10 Å.

44. A method for sequencing DNA or RNA comprising the steps of:

providing an insulating member, the insulating member including a through aperture extending between opposing surfaces and wherein a width of the through aperture is established by a plurality of crystals that are arranged in fixed relation with respect to each other while forming the insulating member;

coating at least inner surfaces of the through aperture with a PNA including one of the A, T, G or C bases that characterize DNA/ RNA;

locating the insulating member between ionic reservoirs at least one of which includes the DNA/RNA to be sequenced;

operably coupling coupling one end of the DNA/RNA to an optical tweezer; measuring a force as a function of time at said one end as said DNA/RNA is pulled through the through aperture; and

correlating the measured force as a function of time to one of A, T, G, or C bases,

to thereby prepare sequencing the DNA or RNA.

45. A method for sequencing DNA or RNA comprising the steps of:

providing a plurality of nanopore assemblies, each of the plurality of nanopore assemblies including an insulating member having opposed surfaces and a through aperture extending between said surfaces,

assembling the plurality of nanopore assemblies so the through apertures form at least a one-dimensional array of through apertures;

coating at least inner surfaces of the through aperture of each of the plurality of nanopore assemblies with a PNA including one of the A, T, G or C bases that characterize DNA/RNA;

locating the insulating member of each nanopore assembly so an ionic reservoir which includes the DNA/RNA to be sequenced is disposed on a side of at least one of the plurality of nanopore assemblies;

operably coupling coupling one end of the DNA/RNA for the through aperture of said at least one nanopore assembly to an optical tweezer;

measuring a force as a function of time at said one end as said DNA/RNA is pulled through the through aperture of said at least one nanopore assembly;

correlating the measured force as a function of time to one of A, T, G, or C bases, to thereby sequencing the DNA or RNA; and

wherein said providing a plurality of nanopore assemblies includes performing the steps of for each nanopore assembly: forming an aperture having a width that is established by fixing a plurality of crystals fixed in position to one another, forming an insulating member by casting an insulating material over said plurality of crystals fixed in position relative to one another, thereby forming the insulating material with said aperture extending through opposing surfaces of said insulating material, removing said plurality of crystals, and coating at least inner surfaces of the through aperture with a PNA including one of the A, T, G or C bases that characterize DNA/RNA;

46. The device of claim 1, further comprising a coating of a PNA including one of the A, T, G or C bases that characterize DNA/RNA; wherein the coating is applied so as to coat at least inner surfaces of the through aperture.

47. The electrically-addressable nanopore array of claim 8, further comprising a coating of a PNA including one of the A, T, G or C bases that characterize DNA/RNA; wherein the coating is applied so as to coat at least inner surfaces of the opening formed at the intersections of each of the grooves in the first and second surfaces.

48. The nanopore of claim 17, further comprising a coating of a PNA including one of the A, T, G or C bases that characterize DNA/RNA; wherein the coating is applied so as to coat at least inner surfaces of the through aperture.

49. The nanopore array of claim 19, further comprising a coating of a PNA including one of the A, T, G or C bases that characterize DNA/RNA; wherein the coating is applied so as to coat at least inner surfaces of the through aperture for each of the plurality of nanopores.

50. A method for sequencing DNA or RNA comprising the steps of:

providing any one of the device of claim 46, the electrically-addressable nanopore array of claim 47, the nanopore of claim 48 and the nanopore array of claim 49;

locating said any one of the device, the electrically-addressable nanopore array, the nanopore and the nanopore array so as to be between ionic reservoirs at least one of which includes the DNA/RNA to be sequenced;

operably coupling coupling one end of the DNA/RNA to an optical tweezer;

measuring a force as a function of time at said one end as said DNA/RNA is pulled through the through aperture; and

correlating the measured force as a function of time to one of A, T, G, or C bases,

to thereby prepare sequencing the DNA or RNA.

51. The method for preparing a nanopore according to claim 22, further comprising the step of coating at least inner surfaces of the through aperture with a PNA including one of the A, T, G or C bases that characterize DNA/RNA;

52. The method for preparing a nanopore array according to claim 24, further comprising the step of coating at least inner surfaces of the one or more through apertures with a PNA including one of the A, T, G or C bases that characterize DNA/RNA;