ATR-FTIR for non-invasive detection of colitis
Disclosed are methods, systems, and apparatuses for non-invasive detection of colitis in a subject. The methods involve depositing a bodily fluid sample from the subject on an internal reflection element (IRE). A beam of infrared (IR) radiation can then be directed through the IRE under conditions such that the IR radiation interacts with the bodily fluid sample. An absorption spectrum can then be recorded over a range of preselected frequencies to detect peaks that are affected by colitis. In preferred embodiments, the methods and systems involve Fourier Transform Infrared Spectroscopy (FTIR).
1. A method for detecting inflammation in a subject, comprising:
(a) depositing a bodily fluid sample from the subject on an internal reflection element (IRE);
(b) directing a beam of infrared (IR) radiation through the IRE under conditions such that the IR radiation interacts with the bodily fluid sample;
(c) recording an absorption spectrum over a range of preselected frequencies;
(d) comparing the absorption spectrum to a control spectrum to identify spectral events associated with inflammation; and
(e) treating the subject for colitis if an increase in the ratio of 1650:1635 cm −1 peaks compared to a normal control is detected; or treating the subject for arthritis if peaks are detected at 1033 cm −1 but not 1076 cm −1 ; or treating the subject for arthritis if peaks are detected at 1292 cm −1 .
2. The method of claim 1 , wherein the IRE is an attenuated total reflectance (ATR) crystal comprising an optical material with a higher refractive index than the sample.
3. The method of claim 2 , wherein the IRE comprises a germanium crystal or a zinc selenide crystal.
4. The method of claim 1 , wherein the IR radiation that interacts with the bodily fluid sample is an evanescent wave with an average penetration depth of about 2 μm.
5. The method of claim 1 , further comprising Fourier transformation of the absorbance spectrum.
6. The method of claim 1 , wherein the range of preselected frequencies is between 50 cm −1 and 3700 cm −1 .
7. The method of claim 1 , wherein the bodily fluid sample comprises a blood, serum, or plasma sample.