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

Abstract

Monitoring of changes in the concentrations of the low molecular weight constituents enhanced by abundant proteins depletion.

Raman spectroscopic analysis of high molecular weight proteins in solution – considerations for sample analysis and data pre-processing

“…The RMSECV of 0.0568 mg mL −1 compares favourably with similar observations, for example for attenuated total reflection -Fourier transform infrared absorption monitoring of glucose in blood serum. 47 The accuracy of this study is closer to that of the most commonly used gold-standard method i.e., the Clauss assay, which has a detection limit of ∼0.4 mg mL −1 . 48 The Clauss assay is relatively time consuming and suffers from inconsistencies in the results due to calibration standards, methodologies and variation in the reagents from various manufacturers.…”

Qualitative and quantitative analysis of therapeutic solutions using Raman and infrared spectroscopy

“…They have been extensively studied for biomedical applications [10,11] can be used and exploited as novel and accurate methods for histopathology [12], cytology [13], biopsy characterisation [14], surgical guidance [15], treatment monitoring [16] and drug studies [17]. The rapid, cost effective, label free and non-destructive advantages are indeed often pointed out to highlight the benefits of those techniques, but it is the analytical capabilities in terms of both qualitative and quantitative performances are also most relevant for a wide range of clinically oriented applications [18,19]. IR and Raman spectroscopy are powerful analytical tools widely used for characterisation of organic molecules such as, for example, therapeutic drugs [20].…”

Potential of Raman spectroscopy for the analysis of plasma/serum in the liquid state: recent advances

“…Although Raman and IR spectroscopy are considered complementary techniques, the fundamental physical phenomena governing them are very different, and thus result in distinct technical challenges to their clinical implementation [6,38]. As IR spectroscopy is based on absorption due to electric dipole transitions associated with molecular vibrations, water cannot be used as a solvent, due to its intense absorption in the IR region due to the highly polar OH groups [39,40]. IR analysis of bodily fluids has therefore been predominantly performed on air-dried samples, which leads to chemical and physical inhomogeneity due to the socalled "coffee ring" effect and thereby inconsistencies in the results obtained [18,19,39].…”

“…The analysis protocols to detect the imbalances in glucose using Raman spectroscopy were first demonstrated for aqueous solutions and spiked serum samples. As in the case of infrared absorption studies [40], centrifugal filtration was utilised to deplete abundant analytes and to reveal the spectral features of LMWF analytes, in order to improve spectral sensitivity and detection limits. After the depletion of the abundant proteins, the dominant water peak from the filtrate collected after centrifugal filtration using 10kDa can be removed by using the EMSC algorithm, and PLSR analysis applied to obtain a prediction model relating the glucose concentrations and the intensity of glucose features.…”

“…Having removed the spectral interferents using EMSC, PLSR can independently identify spectral correlation associated with target analyte range. Cross-validation of the PLSR model is required to evaluate the accuracy, often cited in terms of the Root Mean Square Error of Cross Validation (RMSECV) [93]. The number of latent variables used for construction of the PLSR model is optimised by establishing the value that is equivalent to the minimum of the RMSECV.…”