Raman spectral analysis of pathogens

• US 7,755,756 B2
• Filed: 08/14/2008
• Issued: 07/13/2010
• Est. Priority Date: 01/10/2003
• Status: Active Grant

• Current Assignee: Chemimage Corporation
• Original Assignee: Chemimage Corporation
• Inventors: Stewart, Shona, Treado, Patrick J., Maier, John S.
• Primary Examiner(s): EVANS, FANNIE L
• Application Number:
  US12/191,559
• Publication Number:
  US 20090122309A1
• Time in Patent Office: 698 Days
• Field of Search: 356/301
• US Class Current: 356/301
• CPC Class Codes: A61B 18/20 using laser
• CPC Class Codes: G01J 3/10 Arrangements of light sources specially adapted for spectrometry or colorimetry
• CPC Class Codes: G01J 3/44 Raman spectrometry; Scattering spectrometry ; Fluorescence spectrometry
• CPC Class Codes: G01N 2021/6423 Spectral mapping, video display
• CPC Class Codes: G01N 2021/656 Raman microprobe
• CPC Class Codes: G01N 21/31 Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry G01N21/72 takes precedence
• CPC Class Codes: G01N 21/645 Specially adapted constructive features of fluorimeters
• CPC Class Codes: G01N 21/6458 Fluorescence microscopy fluorescence microscopes per se G02B21/0076 and G02B21/16
• CPC Class Codes: G01N 21/6486 Measuring fluorescence of biological material, e.g. DNA, RNA, cells G01N21/6428 takes precedence
• CPC Class Codes: G01N 21/65 Raman scattering
• CPC Class Codes: G01N 21/658 enhancement Raman, e.g. surface plasmons

Abstract

A method of assessing occurrence of a plant pathogen in a sample. The method comprises irradiating the sample and assessing radiation scattered from the sample for radiation that exhibits a Raman scattering characteristic of the pathogen. Detection of scattered radiation that exhibits a Raman shift characteristic of the pathogen is an indication that the pathogen occurs in the sample.

Claims

1. A method of assessing occurrence of a plant pathogen in a sample, the method comprising irradiating the sample and assessing radiation scattered from the sample for radiation that exhibits a Raman scattering characteristic of the plant pathogen, wherein detection of scattered radiation that exhibits a Raman shift characteristic of the pathogen is an indication that the pathogen occurs in the sample.

2. The method of claim 1, wherein the plant pathogen is selected from the group consisting of Burkholderia solanacearum, citrus greening disease bacteria, Erwinia amylovora, Xanthomonas albilineans, Xanthomonas axonopodis pv. citri, Bipolaris (Helminthosporium) maydis, Claviceps purpurea, Collectotrichum coffeanum virulans, Cochiliobolus miyabeanus, Dothistromia pini, Fusarium oxysporum, Microcystis ulei, Neovossia indica, Peronospora hyoscyami, Puccinia erianthi, Puccinia graminis, Puccinia graminis f. sp. tritici, Puccinia striiformis, Pyricularia grisea, Sclerotinia sclerotiorum, Sclerotium rolfsii, Tilletia indica, Ustilago maydis, Phytophthora infestans, and Fiji disease virus.

3. The method of claim 1, further comprising assessing scattered radiation at a plurality of RS values in a range from 500 to 3250 cm⁻

1, and wherein detection of scattered radiation comprises detection of scattered light that exhibits a Raman shift (RS) value selected from the group consisting of RS values in the range from 500 to 3250 cm<sup>−

1</sup>.

4. The method of claim 1, where in the Raman scattering characteristic is a Raman spectrum over at least a portion of RS values in the range from 500 to 3250 cm⁻

1.

5. The method of claim 1, comprising comparing i) Raman light scattered from the sample with ii) a reference value corresponding to Raman light scattered from a sample of the same type that does not comprise the plant pathogen.

6. The method of claim 1, comprising comparing i) Raman light scattered from a portion of the sample which exhibits a non-Raman optical property characteristic of the plant pathogen with ii) Raman light scattered from a portion of the sample which does not exhibit the property.

7. The method of claim 1, wherein the sample is irradiated with substantially monochromatic light.

8. The method of claim 7, wherein the light is in the visible range of the spectrum.

9. The method of claim 1, wherein the sample is irradiated with polarized radiation.

10. The method of claim 1, wherein the sample is dehumidified prior to assessing radiation scattered by the sample.

11. The method of claim 10, wherein the sample is substantially dried prior to assessing radiation scattered by the sample.

12. The method of claim 11, wherein the sample is substantially dried on a Raman enhancing surface.

13. The method of claim 12, wherein the surface comprises a colloidal metal.

14. The method of claim 1, wherein the sample is contacted with a porous substrate prior to assessing radiation scattered by the sample.

15. The method of claim 14, wherein the substrate substantially excludes particles having a characteristic dimension substantially greater than the largest characteristic dimension of the pathogen.

16. The method of claim 14, wherein the substrate is an ultrafiltration membrane.

17. The method of claim 14, wherein the substrate does not substantially exclude particles having a characteristic dimension substantially smaller than a characteristic dimension of the plant pathogen.

18. The method of claim 14, wherein the substrate does not substantially exclude particles having a characteristic dimension substantially smaller than the smallest characteristic dimension of the plant pathogen.