Osmotic reaction detector for monitoring biological and non-biological reactions

• US 20050136543A1
• Filed: 12/18/2003
• Published: 06/23/2005
• Est. Priority Date: 12/18/2003
• Status: Active Grant

• Current Assignee: Xerox Corporation (Xerox Holdings Corp.)
• Original Assignee: Xerox Corporation (Xerox Holdings Corp.)
• Inventors: Torres, Francisco E., Shrader, Eric, Littau, Karl
• Granted Patent: US 7,615,375 B2
• Time in Patent Office: Days
• US Class Current: 436/34
• CPC Class Codes: G01N 13/04 Investigating osmotic effects
• CPC Class Codes: G01N 7/10 by allowing diffusion of components through a porous wall and measuring a pressure or volume difference
• CPC Class Codes: Y10T 436/11 Automated chemical analysis

Abstract

A method and apparatus for measuring the presence or absence of reaction between a first and second material of interest by measuring osmotic pressure changes in a reaction cell. The reaction cell is capable of measuring the small changes in pressure that occur due to osmotic pressure shifts during a catalytic or binding reaction at species concentrations down to approximately 10⁻⁷ M.

Claims

1. A method for monitoring reactivity in reactions between a first and second material of interest, said method comprising the steps of:

a) providing an osmotic reaction cell comprising first and second wells and a semi-permeable membrane separating said first and second wells;

b) introducing a reference solution comprising any one or combination of the first material of interest, the second material of interest, a surrogate reference material and a carrier fluid into one of said first well and said second well;

c) introducing a reaction mixture into one of said first well or said second well, which does not contain said reference solution, said reaction mixture comprising a carrier fluid and said first and second materials of interest; and

d) monitoring a change in an osmotic pressure in said osmotic reaction cell occurring as a result of a change in concentration in said osmotic reaction cell of one or more of said first material, second material, surrogate reference material or reaction products formed from said first and second materials.

2. A method according to claim 1, wherein said method monitors reactions in said reaction cell at an initial concentration of said first and second materials of interest in said reaction mixture in the range of approximately 5×

10<sup>−

5</sup> M to 5×

10<sup>−

7</sup> M.

3. A method according to claim 1, wherein said method monitors reactions in said reaction cell at an initial concentration of said first and second materials of interest in said reaction mixture as low as approximately 5×

10<sup>−

7</sup> M.

4. A method according to claim 1, wherein said method measures osmotic pressure changes in a range of approximately 1.2 N/m² to 130 N/m².

5. A method according to claim 1, wherein said step d) is performed by measuring the amount of deformation in a flexible diaphragm operatively associated with said osmotic reaction cell.

6. A method according to claim 5, wherein said diaphragm has an effective spring constant of from approximately 0.1 to approximately 2.5 N/m.

7. A method according to claim 1, wherein said method measures osmotic pressure changes of from approximately 1.2 N/m² or greater.

8. A method according to claim 1, wherein said method is performed using an array of osmotic cells, and at least two of the osmotic cells of the array utilize different first and/or second materials.

9. A method according to claim 8, wherein said method for monitoring monitors at least two osmotic cells simultaneously.

10. A method according to claim 5, wherein said amount of deformation is measured by a change in capacitance of said diaphragm.

11. A method according to claim 5, wherein said amount of deformation is measured by a change in the deflection of light incident on said diaphragm.

12. A method according to claim 5, wherein said amount of deformation is measured by measuring the deflection of a cantilever operatively associated with said diaphragm.

13. A method according to claim 1, wherein at least one of said first and second materials of interest is an antibody, an antigen, a nucleic acid, a oligonucleotide, a polypeptide, a protein, or a ligand.

14. A method according to claim 1, wherein an initial molar concentration of solute molecules in said reference solution is equal to the combined initial molar concentration of said first and second materials of interest in said reaction mixture.

15. A method according to claim 1, wherein said step d) is performed by measuring the change in solution height in a manometer fluidly connected with at least one of said first well and said second well.

16. A method according to claim 15, wherein said change in solution height is measured by determining the resistance between two spaced apart conductors positioned in said manometer.

17. A method according to claim 1, wherein said semi-permeable membrane is impermeable to said first and second materials of interest and said surrogate reference material and is permeable to said carrier fluid.

18. A method according to claim 1, wherein said semi-permeable membrane is impermeable to at least one of said first material, said second material and said surrogate reference material, and is permeable to at least one of said first material and said second material and said surrogate reference material or products of a reaction between said first material and said second material.

19. An osmotic cell system for monitoring reactivity in reactions between a first material of interest and a second material of interest, said osmotic cell system comprising:

a first well for containing one of a reference solution and a reaction mixture comprising first and second materials of interest;

a second well for containing the other of the reference solution and the reaction mixture;

a semi-permeable membrane separating said first well from said second well; and

a pressure sensor for measuring changes in osmotic pressure in one of said first well and said second well.

20. An osmotic cell system according to claim 19, wherein said pressure sensor is a deflectable diaphragm.

21. An osmotic cell system according to claim 20, wherein said diaphragm has an effective spring constant of from 0.1 to 2.5 N/m².

22. An osmotic cell system according to claim 20, wherein said diaphragm has an E modulus of 0.3 MPa to 200 Gpa.

23. An osmotic cell system according to claim 20, wherein said diaphragm has a linear deflection of from approximately 0.025 μ

m to approximately 200 μ

m.

24. An osmotic cell system according to claim 19, wherein said pressure sensor comprises a manometer fluidly connected to at least one of said first well and said second well to measure the level of fluid in said manometer.

25. An osmotic cell system according to claim 24, further comprising a resistance detector positioned across said manometer for measuring the level of fluid in said manometer.

26. An osmotic cell system according to claim 24, further comprising a laser for measuring the level of fluid in said manometer.

27. An osmotic cell system according to claim 19, wherein said first and second wells have a volume of from approximately 0.05 μ

l to approximately 100 μ

l.

28. An osmotic cell system according to claim 19, wherein said semi-permeable membrane has molecular weight cutoffs ranging from 100 Dalton to 300,000 Dalton.

29. An osmotic cell system according to claim 19, wherein said pressure sensor comprises an electroactive polymer.

30. An osmotic cell system according to claim 20, wherein said deflectable diaphragm comprises an electroactive polymer.

31. An osmotic cell system according to claim 19, wherein said pressure sensor comprises a deformable gel.

32. A method for monitoring reactions, the method comprising measuring osmotic pressure changes in a reaction cell comprising first and second wells and a semi-permeable membrane;

said reaction cell containing a reference solution and a reaction mixture, wherein said method of measuring includes measuring said osmotic pressure changes as low as 1.2 N/m².

33. A method for monitoring reactions, the method comprising measuring osmotic pressure changes in individual reaction cells positioned in an array of parallel reaction cells, each reaction cell comprising first and second wells and a semi-permeable membrane;

said reaction cells each containing a reaction mixture and a reference solution, wherein said method of measuring includes measuring said osmotic pressure changes as low as 1.2 N/m².