Investigating optimum sample preparation for infrared spectroscopic serum diagnostics

Abstract

Biofluids, such as serum and plasma, represent an ideal medium for disease diagnosis due to their non-invasive character, ease of collection, that can be performed worldwide, and their fundamental involvement in human functions.

Clinical applications of infrared and Raman spectroscopy: state of play and future challenges

“…Compositions and concentrations vary significantly across the dried droplet, due to different molecular weights and relative molecular solubilities, and can cause band saturation in transmission FTIR [26] but Raman signals are highly reproducible within the ring. Lovergne et al performed an infrared microspectroscopic imaging study on pure, 2 fold, 3 fold and 4 fold diluted serum (serum diluted with deionised water) [141]. The images (Figure 7) highlight the spectral and visible differences between the different sample states.…”

“…Other spectral images were constructed using a single wavenumber. Reproduced from [141] In vitro For in vitro cytological studies, formalin fixation has been demonstrated to best reproduce the characteristics of live cells [147]. Protein coated substrates [148] and 3-D matrices have also been explored to improve measurement protocols [149,150].…”

Investigating pre‐analytical requirements for serum and plasma based infrared spectro‐diagnostic

“…A study by attenuated total reflectance (ATR)‐FTIR spectroscopy has reported that spectra acquired on pure serum drop cracks suffer from spectral distortions resulting in an abnormal amide I/ II band shape and baseline . Using HT‐FTIR spectroscopy in the transmission mode, we have previously shown the necessity to dilute serum samples to avoid amide bands spectral saturation, providing visually dried drops with greater homogeneity . Moreover, one averaged spectrum is acquired over the whole surface of a silicon plate well.…”

Ultra-filtration of human serum for improved quantitative analysis of low molecular weight biomarkers using ATR-IR spectroscopy

“…The volume deposited can have a influence on the data collected, depending on the concentration of the solutions analysed and the coverage of the crystal achieved. The socalled "coffee ring effect" has been documented extensively in literature 53,57 and describes the uneven distribution of the constituents following air drying. Commonly, a higher concentration is obtained on the edge of the deposited material which can result in some spectral variability.…”