System and method for identifying proteins

• US 20060084186A1
• Filed: 10/19/2004
• Published: 04/20/2006
• Est. Priority Date: 10/19/2004
• Status: Abandoned Application

• Current Assignee: Hewlett-Packard Development Company, L.P. (HP Inc.)
• Original Assignee: Hewlett-Packard Development Company, L.P. (HP Inc.)
• Inventors: Sharma, Manish, Bratkovski, Alex, Chaiken, Alison
• Application Number:
  US10/969,439
• Publication Number:
  US 20060084186A1
• Time in Patent Office: Days
• US Class Current: 436/518
• CPC Class Codes: G01N 25/4813 concerning the measuring means

Abstract

A method is disclosed for identifying one or more specific proteins in a heterogeneous test solution with a plurality of micro-cantilevers which have two or more conductive arms coupled to an end area having a higher resistance than the conductive arms. The method includes the operation of heating each end area of the plurality of micro-cantilevers by passing a current through each end area. A further operation includes increasing a temperature of the heterogeneous test solution using each heated end area of each of the plurality of micro-cantilevers. Another operation involves measuring a temperature change in the heterogeneous test solution that occurs when a specific protein denatures while heating the heterogeneous test solution with the plurality of micro-cantilevers. A further operation includes identifying the one or more specific proteins in the heterogeneous test solution according to the temperature at which each of the specific proteins denatured.

Claims

1. A method for identifying one or more specific proteins in a heterogeneous test solution using a plurality of micro-cantilevers having conductive arms coupled to an end area having a higher resistance than the conductive arms, comprising:

heating each end area of the plurality of micro-cantilevers by passing a current through each end area having the higher resistance than the conductive arms;

increasing a temperature of the heterogeneous test solution using each heated end area of each of the plurality of micro-cantilevers;

measuring a temperature change in the heterogeneous test solution that occurs when a specific protein denatures while heating the heterogeneous test solution with the plurality of micro-cantilevers; and

identifying the one or more specific proteins in the heterogeneous test solution according to the temperature at which each of the one or more specific proteins denatured.

2. A method as in claim 1, further comprising configuring the plurality of micro-cantilevers as single crystal micro-cantilevers having sharpened tips.

3. A method as in claim 1, further comprising heavily doping the conductive arms of the plurality of micro-cantilevers to enable the arms to be conductive.

4. A method as in claim 3, further comprising increasing the temperature coefficient of resistivity of the plurality of micro-cantilevers by doping one or more end areas of the plurality of micro-cantilevers with one or more conducting oxide thermistor materials selected from the group consisting of La_1-xCa_xMnO3 and Ba_(1-x)Sr_xO, where x is an integer.

5. A method as in claim 3, further comprising doping each end area of the cantilevers less than the conductive arms to enable the each end area to have the higher resistance than the conductive arms.

6. A method as in claim 1, further comprising configuring the plurality of micro-cantilevers in a Wheatstone bridge circuit configuration having two or more micro-cantilevers with heatable end areas.

7. A method as in claim 6, further comprising configuring the plurality of micro-cantilevers in the Wheatstone bridge circuit wherein the Wheatstone bridge circuit comprises two resistors and two micro-cantilevers, the cantilevers each having a heatable end area.

8. A method as in claim 6, further comprising positioning at least one of the heatable end areas of the two or more micro-cantilevers in a micro-fluidic cell containing a test solution.

9. A method as in claim 6, further comprising positioning each of the heatable end areas of the two or more micro-cantilevers in a micro-fluidic channel.

10. A method as in claim 9, further comprising placing a heatable end area of a first cantilever in a first micro-fluidic channel wherein a buffer solution is located in the first micro-fluidic channel.

11. A method as in claim 9, further comprising placing a heatable end area of a second cantilever in a second micro-fluidic channel wherein a test solution is located in the second micro-fluidic channel.

12. A method as in claim 1, further comprising performing a measurement using a heatable end area of a cantilever in a micro-fluidic channel containing a test solution and a plurality of heatable end areas of a plurality of cantilevers in a plurality of micro-fluidic channels containing a buffer solution.

13. A method as in claim 1, further comprising performing a plurality of measurements using a heatable end area of a cantilever in a micro-fluidic channel containing a buffer solution and a plurality of heatable end areas of a plurality of micro-cantilevers in a plurality of microfluidic channels containing a plurality of test solutions.

14. A method as in claim 7, further comprising balancing the Wheatstone bridge circuit by adjusting the resistance of each of the two resistors and each of the two micro-cantilevers with heatable end areas to be substantially equal.

15. A method as in claim 1, further comprising heating the end areas of the plurality of micro-cantilevers by sending the current through the end areas having the higher resistance, wherein the current is a pulse of electrical current.

16. A method as in claim 15, further comprising sending the pulse of electrical current through the end areas, wherein the pulse has a time duration sufficient to allow desired proteins in the heterogeneous test solution to denature in response to increased heat caused by the pulse of electrical current flowing through the end areas.

17. A method as in claim 1, further comprising heating the end areas of the plurality of micro-cantilevers with the current, wherein the current comprises a DC electrical current sent through the end areas.

18. A method as in claim 17, further comprising sending a small DC electrical current through the end areas and increasing DC electrical current until the end areas have reached a desired temperature for a predetermined amount of time.

19. A method as in claim 17, further comprising coupling a small AC electrical signal to the DC electrical current and using a lock-in amplifier to determine a change in AC current, wherein the change in AC current is proportional to the change in temperature of the end areas of the plurality of micro-cantilevers.

20. A method as in claim 1, further comprising applying a non-specific binding agent for proteins to one or more of the plurality of micro-cantilevers.

21. A method as in claim 20, further comprising exposing one or more of the plurality of micro-cantilevers in a Wheatstone bridge circuit to a buffered solution, the buffered solution having similar characteristics to a test solution.

22. A method as in claim 21, further comprising providing the buffered solution having similar characteristics to the test solution including temperature, pH, and salt concentration.

23. A method as in claim 22, further comprising changing the similar characteristics of the test solution when a first protein has a substantially similar temperature of denaturization as a second protein in order to distinguish between the first and second proteins.

24. A method as in claim 23, further comprising changing the similar characteristics of the test solution by altering one or more of the pH and salt concentration of the test and buffer solutions.

25. A method as in claim 1, further comprising determining an amount of a first reactant in the heterogeneous test solution by adding an amount of a second reactant configured to chemically react with the first reactant, wherein a heat of reaction can be measured using the plurality of micro-cantilevers and the amount of the first reactant can be determined by measuring the amount of the second reactant required for the reaction between the first reactant and the second reactant to stop when substantially all of the first reactant has reacted with the second reactant.

26. A proteomic identification system, comprising:

a test chip comprising a plurality of micro-fluidic channels;

a plurality of micro-cantilevers having conductive arms with end areas located near an end of the conductive arms, the end areas having a higher resistance than the conductive arms, wherein one or more of the end areas of the plurality of micro-cantilevers extend into one or more of the plurality of micro-fluidic device channels;

a current source configured to supply current to heat the end areas of the plurality of micro-cantilevers; and

a current measurement module configured to detect changes in current in the plurality of micro-cantilevers caused by a change in temperature of the micro-cantilever.

27. The proteomic identification system of claim 26, further comprising configuring one or more of the plurality of micro-cantilevers as a resistive device in a Wheatstone bridge configuration.

28. The proteomic identification system of claim 27, wherein the Wheatstone bridge configuration comprises two micro-cantilevers and two resistive devices.

29. The proteomic identification system of claim 27, wherein the two resistive devices are potentiometers configured to be adjusted to have substantially similar resistive properties as the two micro-cantilevers in order to balance the Wheatstone bridge circuit.

30. The proteomic identification system of claim 26, further comprising a digital memory device coupled to the test chip and configured to store heat capacities of a plurality of proteins.

31. The proteomic identification system of claim 30, further comprising a micro processing device in communication with the test chip and a solid state memory device and configured to compare changes in temperature of the end areas with the heat capacities of proteins stored on the digital memory device.

32. The proteomic identification system of claim 30, wherein the digital memory device is selected from a group consisting of random access memory (RAM), magnetic RAM, flash memory, a magnetic hard drive, and an optical disk.

33. The proteomic identification system of claim 26, further comprising a wireless communication system configured to enable remote access to the proteomic identification system.

34. The proteomic identification system of claim 33, wherein the wireless communication system is configured to operate according to a standard selected from a group of IEEE 802.11, IEEE 802.15, and IEEE 802.16.