Method for detecting an unknown contaminant concentration in a substance

• US 7,939,343 B2
• Filed: 09/24/2007
• Issued: 05/10/2011
• Est. Priority Date: 01/07/2005
• Status: Expired due to Fees

• Current Assignee: The Board of Trustees of the University of Arkansas (University of Arkansas System)
• Original Assignee: The Board of Trustees of the University of Arkansas (University of Arkansas System)
• Inventors: Li, Yanbin, Su, Xiao-Li
• Primary Examiner(s): Moran; Marjorie
• Assistant Examiner(s): Skibinsky; Anna
• Application Number:
  US11/860,180
• Publication Number:
  US 20080206791A1
• Time in Patent Office: 1,324 Days
• Field of Search: None
• US Class Current: 436/518
• CPC Class Codes: G01N 33/54373 involving physiochemical end-point determination, e.g. wave-guides, FETS, gratings
• CPC Class Codes: G01N 33/56911 Bacteria

Abstract

A method for determining a concentration of a contaminant in a first sample, the method including producing the first sample, including adding a plurality of immuno-beads to a test substance; exposing a crystal microbalance immunosensor to the first sample; determining a change in a first motional resistance of the crystal microbalance immunosensor following exposure to the first sample (ΔR₁); and determining the concentration of the contaminant in the first sample according to ΔR₁.

Claims

1. A method for determining a concentration of a contaminant in a first sample, the method comprising:

producing the first sample, comprising adding a plurality of immuno-magnetic beads to a test substance;

exposing a crystal microbalance (CM) immunosensor to the first sample;

determining a change in a first motional resistance of the crystal microbalance immunosensor following exposure to the first sample (Δ

R₁); and

determining the concentration of the contaminant in the first sample according to Δ

R₁.

2. The method of claim 1, wherein the crystal includes quartz.

3. The method of claim 1 wherein the test substance is a food substance.

4. The method of claim 1, wherein Δ

R₁ is measured using a quartz crystal analyzer.

5. The method of claim 1, wherein determining Δ

R₁ includes measuring Δ

R₁.

6. The method of claim 1, wherein determining Δ

R₁ includes measuring a conductance (G_f1) and a susceptance (B_f1) of the CM immunosensor exposed to the first sample.

7. The method of claim 6, wherein G_f1 and B_f1 are measured approximately simultaneously.

8. The method of claim 6, wherein Δ

R₁ is determined as a function of G_f1 and B_f1 using a Butterworth-Van Dyke model.

9. The method of claim 1 wherein the contaminant is a Salmonella typhimurium.

10. The method of claim 1 wherein the immuno-magnetic beads comprise an antibody specific for a Salmonella species.

11. The method of claim 1 wherein the immuno-magnetic beads comprise an antibody specific for Salmonella typhimurium.

12. The method of claim 1 wherein the test substance comprises a food sample, a blood sample, or a urine sample.

13. The method of claim 1 wherein the immuno-magnetic beads comprise immuno-magnetic microbeads, or immuno-magnetic nanobeads.

14. The method of claim 1, further comprising:

adding a plurality of immuno-magnetic beads to a plurality of second samples, wherein each of the second samples comprises a known concentration of the contaminant;

exposing the CM immunosensor to the plurality of second samples; and

determining a change in a second motional resistance (Δ

R₂) of the CM immunosensor exposed to the plurality of second samples.

15. The method of claim 14, wherein determining Δ

R₂ comprises measuring a conductance (G_f2) and a susceptance (B_f2) of the CM immunosensor exposed to the plurality of second samples.

16. The method of claim 15, wherein Δ

R₂ is determined as a function of G_f2 and B_f2 using a Butterworth-Van Dyke model.

17. The method of claim 1 wherein the contaminant is a pathogen, a bacterium, a virus, an insect, or an arachnid.

18. The method of claim 1 wherein producing the first sample further comprises separating the immuno-magnetic beads from the test substance.

19. The method of claim 1 wherein producing the first sample further comprises magnetically separating the immuno-magnetic beads from the test substance.

20. The method of claim 1, wherein the first sample is exposed to the CM immunosensor without separating the immuno-magnetic beads from the test substance.