Fiber optic D dimer biosensor

• US 5,938,595 A
• Filed: 05/24/1996
• Issued: 08/17/1999
• Est. Priority Date: 05/24/1996
• Status: Expired due to Fees

• Current Assignee: Lawrence Livermore National Security LLC (Government of the United States of America)
• Original Assignee: Regents of the University of California (University of California)
• Inventors: Grant, Sheila A., Glass, Robert S.
• Primary Examiner(s): Dvorak, Linda C.M.
• Assistant Examiner(s): YARNELL, BRYAN KEITH
• Application Number:
  US08/653,183
• Time in Patent Office: 1,180 Days
• Field of Search: 128/633, 128/634, 128/664, 128/665, 422/82.05-82.08, 422/82.11, 436/86, 436/172, 356/39, 600/341, 600/342, 600/474, 600/476
• US Class Current: 600/342
• CPC Class Codes: A61B 5/0084 for introduction into the body, e.g. by catheters A61B5/1459 takes precedence
• CPC Class Codes: G01N 33/86 involving blood coagulating time or factors, or their receptors

Abstract

A fiber optic sensor for D dimer (a fibrinolytic product) can be used in vivo (e.g., in catheter-based procedures) for the diagnosis and treatment of stroke-related conditions in humans. Stroke is the third leading cause of death in the United States. It has been estimated that strokes and stroke-related disorders cost Americans between $15-30 billion annually. Relatively recently, new medical procedures have been developed for the treatment of stroke. These endovascular procedures rely upon the use of microcatheters. These procedures could be facilitated with this sensor for D dimer integrated with a microcatheter for the diagnosis of clot type, and as an indicator of the effectiveness, or end-point of thrombolytic therapy.

Claims

1. A D dimer biosensor for the diagnosis and treatment of stroke and stroke-related conditions, comprising:

a fiber optic having a proximal end and a distal end;

a coating affixed to said distal end of said fiber optic, wherein said coating comprises P-HEMA (poly(2-hydroxyethyl methacrylate);

mouse anti-human monoclonal antibody that has been tagged with a fluorescent molecule, wherein said coating encapsulates said mouse anti-human monoclonal antibody, wherein said D dimer biosensor is used for the diagnosis and treatment of stroke and stroke-related conditions.

2. The D dimer sensor of claim 1, wherein said fluorescent molecule comprises fluorescein isothiocyanate (FITC).

3. The D dimer sensor of claim 2, wherein said FITC is excited by 485 nm incident wavelength and fluoresces at 520 nm wavelength.

4. The D dimer sensor of claim 1, wherein said coating is selected from a group consisting of a polymers, a gel and a transparent sol-gel-derived material.

5. The D dimer sensor of claim 4, wherein said coating is selected from a group consisting of (i) a material produced from sol-gel polymerization of tetraethoxysilane, (ii) a material produced from sol-gel polymerization of tetramethoxysilane, (iii) glutaraldehyde-induced cross-linking of bovine serum albumin, (iv) a hydrogel and (v) a polyurethane.

6. The D dimer sensor of claim 4, wherein said polymer is selected from a group consisting of polyurethane and copolymer of polyurethane.

7. The D dimer sensor of claim 1, further comprising:

a light source;

means for focusing a beam from said light source into said fiber optic; and

means for detecting fluorescence emitted from said fluorescent molecule,

wherein D dimer antigen diffuses into said coating when said distal end of said fiber optic is inserted into a sample comprising said antigen, wherein said antigen binds with said antibodies, wherein the fluorescence properties of said tagging molecule are altered which causes intensity changes, or emission wavelength changes (which form the basis for sensing) resulting in a fluorescence signal that is partially collected by said fiber optic and delivered to said means for detecting said fluorescence emitted from said fluorescent molecule.

8. The D dimer sensor of claim 7, wherein said light source is selected from a group consisting of a monchromatic light source and a polychromatic light source.

9. The D dimer sensor of claim 7, wherein said light source is selected from a group consisting of a tungsten halogen lamp, a light emitting diode and a laser diode.

10. The D dimer sensor of claim 7, wherein said means for detecting fluorescence emitted from said fluorescent molecule comprise:

a chopper producing a reference frequency;

a first lock-in amplifier having a first reference frequency input channel, a reference input channel and a reference output channel for producing a reference output;

a second lock-in amplifier, having a second reference frequency input channel, a signal input channel and a signal output channel for producing a signal output;

a reference detector electrically connected to said reference input channel; and

a signal detector electrically connected to said signal input channel, wherein said chopper reference frequency is electrically connected to said first reference frequency input channel and said second reference frequency input channel, wherein said signal output is divided by said reference output to provide discrimination against background to improve the signal-to-noise ratio.

11. The D dimer sensor of claim 7, further comprising a catheter, wherein said fiber optic is located within said catheter.

12. The D dimer sensor of claim 11, wherein said catheter comprises means for delivery of thrombolytic agents to a blood clot.

13. The D dimer sensor of claim 12, wherein said means for delivery of thrombolytic agents to a blood clot comprise a tube located within said catheter.

14. The D dimer sensor of claim 12, wherein said thrombolytic agents are selected from a group consisting of recombinant tissue plasmingen activator (rt-PA), urokinase and streptokinase.

15. The D dimer sensor of claim 14, wherein said rt-PA is administered at a dosage of 0.9 mg/Kg of body weight.

16. The D dimer sensor of claim 7, wherein said means for detecting fluorescene emitted from said fluorescent molecule are selected from a group consisting of lock-in amplifiers and sample and hold circuits.

17. The D dimer sensor of claim 7, wherein said means for detecting fluorescence emitted from said fluorescent molecule includes two avalanche photodiodies in the photon-counting mode.

18. The D dimer sensor of claim 7, wherein said means for detecting fluorescence emitted from said fluorescent molecule include a timing chip on a lab tender board to trigger an acousto-optic modulator and count the pulses from two avalanche photodiodes in the photon counting mode.

19. The D dimer sensor of claim 1, wherein said fiber optic comprises a substrate from a group consisting of fused silica and polymethlymethacrylate (PMMA).

20. The D dimer sensor of claim 1, wherein said fiber optic comprises a configuration selected from a group consisting of a fiber stripped of its cladding and tapered at an end of said fiber optic, a blunt-end fiber, a fiber having its core etched away and a side-firing fiber having its tip polished at a 45 degree angle.

21. The D dimer sensor of claim 20, wherein said fiber optic comprises a diameter with a range from 50 μ

m to 300 μ

m.

22. A method of detecting D dimer, comprising:

inserting a D dimer sensor into a blood sample, wherein said D dimer sensor comprises a fiber optic having a coating affixed to a first end thereof, wherein said coating comprises mouse anti-human monoclonal antibodies that have been tagged with fluorescent molecules;

directing a beam of light into a second end of said fiber optic, wherein said beam of light excites said fluorescent molecules to produce fluorescence which is collected by said fiber optic and exits said second end of said fiber optic, wherein said fluorescence is amplitude modulated; and

detecting said fluorescence by a detector that is electrically connected to the signal input channel of a lock-in amplifier, wherein a reference frequency is electrically connected to the reference channel of said lock-in amplifier, wherein said lock-in amplifier provides an analog signal output that is proportional to the intensity of said fluorescence that is detected by said photodiode, wherein the step of inserting a D dimer sensor into a blood sample includes inserting a D dimer sensor within a catheter into the arteriovenous system by threading said catheter through the vascular system up to the site of an occlusion, wherein fluorescence changes can be related to the local concentration of D dimer in the blood, ideally with the biosensor placed as close as possible to, or within a thrombus.

23. The method of claim 22, further comprising the step of using real-time x-ray angiography to guide the placement of said first end of said fiber optic to the site of an occlusion.

24. The method of claim 23, further comprising the step of accessing the femeral artery of a patient and inserting said catheter.

25. The method of claim 24, further comprising the step of delivering thrombolytic agents through a tube placed within said catheter.

26. The method of claim 25, wherein the step of delivering thrombolytic agents includes delivering thrombolytic agents selected from a group consisting of rt-PA, urokinase and streptokinase.

27. The method of claim 25, further comprising the step of directing short laser pulses through said fiber optic to a clot.

28. The method of claim 27, further comprising the step of using thrombolytics in conjunction with said short laser pulses to destroy said clot.

29. The method of claim 28, further comprising the step of isolating said clot by inflating a catheter-delivered microballoon on either side of said clot, wherein the rate at which thrombolytics are delivered into this local "microenvironment" can be controlled to prevent hemorrhage using the D dimer sensor.

30. A D dimer biosensor, comprising:

a fiber optic having a proximal end and a distal end;

a coating affixed to said distal end of said fiber optic, wherein said coating comprises P-HEMA (poly(2-hydroxyethyl methacrylate);

mouse anti-human monoclonal antibody that has been tagged with a fluorescent molecule, wherein said coating encapsulates said mouse anti-human monoclonal antibody;

a light source for producing a beam of light;

a chopper for chopping said beam of light, said chopper producing a reference frequency;

a dichroic mirror for reflecting a first portion of said beam, wherein said dichroic mirror transmits a second portion of said beam;

a lens for focusing said first portion into said proximal end;

a first lock-in amplifier having a first reference frequency input channel, a reference input channel and a reference output channel for producing a reference output;

a second lock-in amplifier, having a second reference frequency input channel, a signal input channel and a signal output channel for producing a signal output;

a reference detector for detecting said second portion of said beam, wherein said reference detector is electrically connected to said reference input channel;

wherein antigen (D dimer) diffuses into said coating when said distal end of said fiber optic is inserted into a sample comprising said antigen, wherein said antigen binds with said antibodies, wherein the fluorescence properties of said tagging molecule are altered which causes intensity changes, or emission wavelength changes (which form the basis for sensing) resulting in a fluorescence signal that is partially collected by in said distal end of said fiber optic and exits said proximal end of said fiber optic to produce a signal beam; and

a signal detector for detecting said signal beam, wherein said signal detector is electrically connected to said signal input channel, wherein said reference frequency from said chopper is electrically connected to said first reference frequency input channel and said second reference frequency input channel, wherein said signal output is divided by said reference output to provide discrimination against background to improve the signal-to-noise ratio.