Reaction system element and method for performing prothrombin time assay

• US 4,849,340 A
• Filed: 04/03/1987
• Issued: 07/18/1989
• Est. Priority Date: 04/03/1987
• Status: Expired due to Term

• Current Assignee: Cardiovascular Diagnostics, Inc. (PharmaNetics, Inc.)
• Original Assignee: Cardiovascular Diagnostics, Inc. (PharmaNetics, Inc.)
• Inventors: Oberhardt, Bruce
• Primary Examiner(s): Warden, Robert J.
• Assistant Examiner(s): Spiegel, Carol A.
• Application Number:
  US07/033,817
• Time in Patent Office: 837 Days
• Field of Search: 435/7, 435/13, 435/310, 436/517, 436/525, 436/526, 436/809, 436/46, 436/69, 422/57, 422/58, 422/73, 422/102, 422/110, 422/292, 73/863.71-863.73, 73/864.72
• US Class Current: 435/13
• CPC Class Codes: B01F 21/00 Dissolving separating by dissolving B01D; dissolving to effect cooling F25D5/00
• CPC Class Codes: B01F 2101/23 Mixing of laboratory samples e.g. in preparation of analysing or testing properties of materials
• CPC Class Codes: B01F 23/40 Mixing liquids with liquids; Emulsifying
• CPC Class Codes: B01F 23/56 by introducing solids in liquids, e.g. dispersing or dissolving
• CPC Class Codes: B01F 31/00 Mixers with shaking, oscillating, or vibrating mechanisms
• CPC Class Codes: B01F 31/31 using receptacles with deformable parts, e.g. membranes, to which a motion is imparted
• CPC Class Codes: B01F 33/30 Micromixers
• CPC Class Codes: B01F 35/7172 using capillary forces
• CPC Class Codes: B01L 2300/0654 Lenses; Optical fibres
• CPC Class Codes: B01L 2300/069 Absorbents; Gels to retain a fluid
• CPC Class Codes: B01L 2300/0825 Test strips
• CPC Class Codes: B01L 2300/0864 comprising only one inlet and multiple receiving wells, e.g. for separation, splitting
• CPC Class Codes: B01L 2300/087 Multiple sequential chambers
• CPC Class Codes: B01L 2300/0887 Laminated structure
• CPC Class Codes: B01L 2300/1827 using resistive heater
• CPC Class Codes: B01L 2300/1861 using radiation
• CPC Class Codes: B01L 2400/0406 capillary forces
• CPC Class Codes: B01L 2400/0633 with moving parts
• CPC Class Codes: B01L 2400/0655 pinch valves
• CPC Class Codes: B01L 2400/0694 vents used to stop and induce flow, backpressure valves
• CPC Class Codes: B01L 3/5023 : with a sample being transported to, and subsequently stored in an absorbent for analysis
• CPC Class Codes: B01L 3/5027 : by integrated microfluidic structures, i.e. dimensions of channels and chambers are such that surface tension forces are important, e.g. lab-on-a-chip B01L3/5023 takes precedence; micromixers B01F33/30; microreactors for synthesis B01J19/0093; microcapillary devices in general B81B1/00
• CPC Class Codes: B01L 3/502715 : characterised by interfacing components, e.g. fluidic, electrical, optical or mechanical interfaces
• CPC Class Codes: B01L 3/50273 : characterised by the means or forces applied to move the fluids micropumps F04B19/006, of the membrane type F04B43/043
• CPC Class Codes: B01L 3/502738 : characterised by integrated valves microvalves F16K99/0001
• CPC Class Codes: G01N 2021/0346 : Capillary cells; Microcells
• CPC Class Codes: G01N 2035/00435 : Refrigerated reagent storage
• CPC Class Codes: G01N 21/51 : inside a container, e.g. in an ampoule G01N21/53 takes precedence
• CPC Class Codes: G01N 21/648 : using evanescent coupling or surface plasmon coupling for the excitation of fluorescence
• CPC Class Codes: G01N 21/78 : producing a change of colour
• CPC Class Codes: G01N 2201/0668 : Multiple paths; optimisable path length
• CPC Class Codes: G01N 33/4905 : Determining clotting time of blood by chemical methods G01N33/86, C12Q1/56
• CPC Class Codes: G01N 33/525 : Multi-layer analytical elements
• CPC Class Codes: G01N 35/0098 : involving analyte bound to insoluble magnetic carrier, e.g. using magnetic separation magnetic particles used in immunoassays G01N33/54326; magnetic separation in general B03C
• CPC Class Codes: Y10S 435/805 : Test papers
• CPC Class Codes: Y10S 435/81 : Packaged device or kit
• CPC Class Codes: Y10S 435/969 : Multiple layering of reactants
• CPC Class Codes: Y10S 435/97 : Test strip or test slide
• CPC Class Codes: Y10S 435/975 : Kit
• CPC Class Codes: Y10S 436/807 : Apparatus included in process claim, e.g. physical support structures
• CPC Class Codes: Y10S 436/81 : Tube, bottle, or dipstick

Abstract

An element and method for easily performing liquid assays are disclosed. The element uses capillary action to draw a predetermined volume of a liquid sample into a reaction chamber charged with reagent, where reaction between the liquid sample and the reagent is monitored.

Claims

1. An analytical system for performing a prothrombin time assay comprising:

(i) a reaction slide bearing (1) a sample well for receiving a liquid sample and (2) a reaction chamber containing a dry reagent matrix in which is embedded a plurality of magnetic particles distributed homogeneously therethrough, wherein said reagent is one member selected from the group consisting of prothrombin time assay reagents;

(ii) said sample well and said reaction chamber being in fluid connection through a transport zone of geometry such that a volume of liquid sample placed in said reaction chamber is transported from said sample well to said reaction chamber simultaneously,

(iii) means for optically monitoring said reaction chamber,

(iv) means for subjecting said reaction chamber to an oscillating magnetic field,

(v) whereby, when said sample is introduced into said reaction chamber, said dry reagent matrix is solubilized and said magnetic particles are thereby freed to move in an oscillating pattern induced by said osicllating magnetic field, thus providing a start and a stop time for said prothrombin time assay, corresponding to a change in the degree of said magnetic particle movement relative to said magnetic field.

2. The analytical system of claim 1, wherein said magnetic particles are magnetite.

3. The analytical system of claim 1, further comprising a means for subjecting said reaction chamber to a permanent magnetic field.

4. The analytical system of claim 1, wherein said means for subjecting said reaction chamber to an osicllating magnetic field is an electromagnet.

5. The analytical system of claim 3, wherein said means for subjecting said reaction chamber to a permanent magnetic field is a permanent magnet.

6. The analytical system of claim 1, wherein said means for monitoring said reaction chamber comprises means for impinging light onto said reaction chamber and means for detecting light reflected from said reaction chamber.

7. The analytical system of claim 1, wherein said dry reagent matrix in which is embedded a plurality of magnetic particles is obtained by adding to said reaction chamber a slurry of reagent and magnetic particles and freeze drying same.

8. The analytical system of claim 7, wherein said magnetic aparticles are present in said slurry in an amount of 5 to 50 milligrams per milliliter.

9. The analytical system of claim 1, wherein said reagent comprises a combination of thromplastin and calcium chloride.

10. A method for performing a prothrombin time assay, comprising:

(i) subjecting to an oscillating magnetic field a reaction slide bearing (1) a sample well for receiving a liquid sample and (2) a reaction chamber containing a dry reagent matrix in which is embedded a plurality of magnetic particles distributed homogeneously therethrough, wherein said reagent is one member selected from the group consisting of prothrombin time assay reagents;

said sample well and reaction chamber being in fluid connection through a transport zone of geometry such that a volume of liquid analyte sample placed in said sample well and corresponding to the volume of said reaction chamber is transported from said sample well to said reaction chamber simultaneously;

(ii) adding a whole blood or plasma sample to said sample well whereby said sample is introduced simultaneously to said reaction chamber, said reagent is solubilized and said particles are freed to move in an oscillating pattern induced by said oscillating magnetic field; and

(iii) optically monitoring said reaction chamber to measure a start time and a stop time for said prothrombin time assay, corresponding to a change in the degree of said particle movement relative to said magnetic field.

11. The method of claim 10, wherein said magnetic particles are magnetite.

12. The method of claim 10, wherein said reaction chamber is subjected to a permanent magnetic field.

13. The method of claim 10, wherein said reaction chamber is optically monitored by impinging light thereon and detecting light reflected from said reaction chamber.

14. The method of claim 10, wherein said sample is a whole blood sample.

15. The method of claim 10, wherein said sample is a plasma sample.

16. The method of claim 10, wherein said reagent comprises thromboplastin and calcium chloride.