This study investigates an application of Fourier transform infrared (FTIR) spectroscopy of blood components in attenuated total reflection (ATR) sampling mode to quantify ulcerative colitis (UC) induced molecular alterations. Using infrared absorbance data of serum samples extracted from Interleukin 10 knockout (IL10-/-) and Dextran Sodium Sulfate (DSS)-induced experimental models of colitis, we have quantified associated markers with the aid of accompanying data analysis techniques. Identified spectral markers are absorbance at wavenumber 1033 cm-1 , which is primarily due to the glucose; 1076 cm-1 , representing mannose as well as phosphate presence; and the ratio of absorbance at 1121 cm-1 RNA presence to its value at 1020 cm-1 , associated with DNA; and at 1629 cm-1 belonging to the protein to its value at 1737 cm-1 belonging to lipids’ presence. Protein secondary structures as observed by spectral deconvolution in the Amide-I band was also identified. The quantified discriminatory values show significant fluctuations in colitis samples compared to their control types. The differentiating signatures between spectra are obtained by observing p-values comparisons, the ratio analysis and the use of statistical measures such as sensitivity and specificity. High diagnostic accuracy is seen with 80-100% sensitivity and specificity values. Thus, quantitative analysis of infrared (IR) spectral data may be useful for disease diagnostics and therapeutic analysis.
The standard threshold wavelength (λt) of an Infrared (IR) detector is related to the energy gap Δ is given by Δ = 1.24/λt . Here, we summarize the results of a new class of IR detectors, that display threshold wavelengths (λteff) (< λt) for the same corresponding Δ designed for λt . The extended threshold (ET) wavelength detectors includes epi-layers of barrieremitter-barrier, which are sandwiched in between the two contact regions. Spectral response of the device structures with different energy offsets between the barriers shows the wavelength extension, while the standard λt is observed without this offset (δ𝐸). The ET wavelength phenomena coupled with a reduced dark current corresponding to the designed Δ could provide a specific detectivity (D*) advantage over conventional detectors. A possible explanation of the results which include the role of potential barrier gradient for the performance of detectors will also be discussed.
There remains a great need for diagnosis of inflammatory bowel disease (IBD), for which the current technique, colonoscopy, is not cost-effective and presents a non-negligible risk for complications. Attenuated Total Reflectance Fourier Transform Infrared (ATR-FTIR) spectroscopy is a new screening technique to evaluate colitis. Comparing infrared spectra of sera to study the differences between them can prove challenging due to the complexity of its biological constituents giving rise to a plethora of vibrational modes. Overcoming these inherent infrared spectral analysis difficulties involving highly overlapping absorbance peaks and the analysis of the data by curve fitting to improve the resolution is discussed. The proposed technique uses colitic and normal wild type mice dried serum to obtain ATR/FTIR spectra to effectively differentiate colitic mice from normal mice. Using this method, Amide I group frequency (specifically, alpha helix to beta sheet ratio of the protein secondary structure) was identified as disease associated spectral signature in addition to the previously reported glucose and mannose signatures in sera of chronic and acute mice models of colitis. Hence, this technique will be able to identify changes in the sera due to various diseases.
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