NANOPORE ELECTRODE, NANOPORE MEMBRANE, METHODS OF PREPARATION AND SURFACE MODIFICATION, AND USE THEREOF

• US 20080121534A1
• Filed: 05/03/2007
• Published: 05/29/2008
• Est. Priority Date: 05/05/2006
• Status: Active Grant

• Current Assignee: University of Utah Research Foundation (State of Utah)
• Original Assignee: University of Utah Research Foundation (State of Utah)
• Inventors: Zhang, Bo, Ervin, Eric N., White, Ryan J., White, Henry S., Wang, Gangli
• Granted Patent: US 7,849,581 B2
• Time in Patent Office: Days
• US Class Current: 205/787.5
• CPC Class Codes: B01D 2325/021 Pore shapes
• CPC Class Codes: B01D 67/006 by elimination of segments of the precursor, e.g. nucleation-track membranes, lithography or laser methods
• CPC Class Codes: B01D 71/04 Glass
• CPC Class Codes: Y10S 977/904 for medical, immunological, body treatment, or diagnosis
• CPC Class Codes: Y10S 977/953 Detector using nanostructure
• CPC Class Codes: Y10T 29/49 Method of mechanical manufacture
• CPC Class Codes: Y10T 29/49002 Electrical device making
• CPC Class Codes: Y10T 29/49004 including measuring or testing of device or component part
• CPC Class Codes: Y10T 29/49826 Assembling or joining

Abstract

Provided are fabrication, characterization and application of a nanodisk electrode, a nanopore electrode and a nanopore membrane. These three nanostructures share common fabrication steps. In one embodiment, the fabrication of a disk electrode involves sealing a sharpened internal signal transduction element (“ISTE”) into a substrate, followed by polishing of the substrate until a nanometer-sized disk of the ISTE is exposed. The fabrication of a nanopore electrode is accomplished by etching the nanodisk electrode to create a pore in the substrate, with the remaining ISTE comprising the pore base. Complete removal of the ISTE yields a nanopore membrane, in which a conical shaped pore is embedded in a thin membrane of the substrate.

Claims

1. A method of preparing a conical nanopore device using at one internal signal transduction element (“

ISTE”

) with a conical, atomically sharp tip, the method comprising;

sealing the conical tip of the at least one ISTE in a substrate;

polishing the substrate using a polishing means in order to expose the tip of the ISTE;

monitoring the extent of the polishing using a tester; and

stopping polishing when the tester signifies that a disk of a desired radius is exposed and thus producing a nanodisk electrode;

wherein the desired radius ranges from about 2 nm to about 500 nm.

2. The method according to claim 1, the method further comprises etching the exposed disk of the ISTE to produce a nanopore electrode.

3. The method according to claim 2, wherein the ISTE comprises platinum or gold.

4. The method according to claim 3, wherein the substrate is glass or quartz.

5. The method according to claim 4, the monitoring step comprises:

measuring intermittently the electrical resistance between the extended part of the ISTE and the polishing means; and

analyzing the electrical resistance as function of the thickness of the substrate or above the tip of the ISTE or as a function of the size of the exposed disk of the ISTE.

6. The method according to claim 5, wherein electrical resistance is analyzed by finite element analysis to estimate the size of the exposed disk of the ISTE.

7. The method according to claim 6, wherein the tester is a high-input impedance metal-oxide semiconductor field effect transistor (MOSFET)-based circuit tester.

8. The method according to claim 5, wherein the monitoring step further comprises:

examining intermittently the electrode during polishing to determine the thickness of the substrate around the sealed conical tip'"'"'s area.

9. The method of claim 5, further comprising:

after a disk of a desired radius is exposed, the exterior surface of the substrate is modified with a first entity; and

after the nanopore is created, the interior surface is modified with a second entity.

10. The method according to claim 9, wherein the first entity is a reactive silane with an inert terminus, and the second entity is a silane that comprises a first functional group able to react with glass and a second functional group able to react with a sensor element able to selectively bind a target analyte.

11. The method of claim 2, further comprising:

removing the ISTE from the substrate after the nanopore is created thus producing a nanopore membrane.

16. The method according to claim 10 wherein the first entity is Cl(Me)₂Si(CH₂)₃CN, and the second entity is EtO(Me)₂Si(CH₂)₃NH₂.

17. The method according to claim 5, further comprising:

removing the ISTE from the substrate after the nanopore is created thus producing a nanopore membrane.

18. The method according to claim 5, further comprising:

removing the ISTE from the substrate after the interior surface is chemically modified thus producing a modified nanopore membrane.

19. The method according claim 17, further comprising:

chemical modifying the interior surface to produce a modified nanopore membrane.

12. A method of using a surface-modified nanopore electrode to control the transport of a charge species, the method comprising:

providing a sample solution containing at least one charged species to be analyzed;

providing a nanopore electrode including an internal signal transduction element (“

ISTE”

), wherein the interior surface of the nanopore comprises an entity that renders the electrical charge density at the pore orifice adjustable by an appropriate adjusting species;

contacting the nanopore electrode with the solution such that the nanopore'"'"'s exterior surface is immersed in the solution and the nanopore is filled with the solution;

applying an appropriate voltage between the solution and the ISTE;

adding the appropriate adjusting species to the solution such that the electrical charge density at the orifice is varied and the at least one charged species passing through the nanopore can be electrostatically gated “

on” and

“

off”

by controlling the electrical charge density at the orifice;

monitoring the electrical conductivity of the nanopore; and

analyzing the electrical conductivity to determine to what extent the transfer of the charged species is controlled.

13. The method according to claim 12, wherein the charged species is a reactant of a redox reaction that takes place around the base of the nanopore;

thus controlling the transport of the charged species through the nanopore orifice controls the rate of the redox reaction.

14. A method of using a surface-modified nanopore electrode to measure the pH of a sample solution, the method comprising:

providing a sample solution;

providing a glass nanopore electrode including an internal signal transduction element (“

ISTE”

), wherein the interior surface of the nanopore comprises an entity that varies the electrical charge density at the pore orifice depending on the pH value of the solution;

contacting the nanopore electrode with the sample solution such that the exterior surface of the nanopore electrode is immersed in the solution and the nanopore is filled with the solutions

applying an appropriate voltage between the solution and the ISTE;

monitoring the electrical conductivity of the nanopore; and

analyzing the electrical conductivity to determine the solution'"'"'s pH.

15. A method of using a surface-modified nanopore electrode to measure the concentration of an analyte of interest in a sample solution, the method comprising:

providing a sample solution containing an analyte of interest;

providing a nanopore electrode including an internal signal transduction element (“

ISTE”

) wherein the interior surface of the nanopore is modified with a functional entity such that the functional entity selectively binds to the analyte of interest;

contacting the nanopore electrode with the solution such that the exterior surface of the nanopore is immersed in the solution and the nanopore is filled with the solution;

applying an appropriate voltage between the solution and the ISTE of the nanopore electrode;

monitoring the electrical conductivity of the nanopore; and

analyzing the electrical conductivity to determine to the concentration of the analyte of interest.

20. A method of using an unmodified or surface-modified nanopore membrane to measure the concentration and properties of an analyte of interest in a sample solution, the method comprising:

providing a sample solution containing an analyte of interest;

providing a nanopore membrane;

contacting the nanopore membrane with solution such that both the exterior and interior surfaces of the nanopore membrane are in contact with solution, wherein either the exterior or interior solution contains the analyte to be analyzed;

applying an appropriate voltage between the solutions on opposite sides of the nanopore membrane;

monitoring the electrical conductivity of the nanopore; and

analyzing the electrical conductivity to determine to the concentration or properties of the analyte of interest.