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1.6 BIOLOGICAL SCIENCES
Analysis of analytes present in the blood stream can potentially deliver crucial information on patient health and indicate the presence of numerous pathologies. Existing clinical techniques for this analysis can, however, be costly and time-consuming. The potential of Raman spectroscopic analysis of human plasma and/or serum for diagnostic purposes has been widely investigated and, increasingly, its feasibility for clinical translation has been explored. However, as the concentration of many analytes in plasma/serum is relatively low, to date such analysis has commonly been performed on air-dried drops deposited on substrates, leading to inhomogeneity and inconsistencies. This study explores the potential of Raman spectroscopy, coupled with fractionation and concentration techniques, as well as multivariate regression analysis, to quantitatively monitor diagnostically relevant changes in high and low molecular weight proteins as well as therapeutic drugs, in liquid plasma/serum. Having optimised the protocols for pure aqueous solutions and spiked serum samples, measurement protocols to detect the imbalances in plasma/serum analytes (fibrinogen, albumin, γ globulins, total protein content, glucose and urea), as an indicator of various diseases, and therapeutic monitoring of drugs (busulfan and methotrexate), using Raman spectroscopy were optimised in liquid serum, such that strategic clinical applications for early stage disease diagnostics and therapeutic drug monitoring can be evaluated. Furthermore, an adapted Extended Multiplicative Signal Correction algorithm was applied to raw spectra to remove background signal and spectral interferents. Using a validated partial least squares regression method, prediction models were built for the analytes, with accuracies which are comparable with those reported for the conventional methods, without any additional sample preparation steps. This methodology was extended to determine the Limit of Detection (LOD) and Limit of Quantification (LOQ) for therapeutic drug monitoring in human serum, using the examples of Busulfan, a cell cycle non-specific alkylating antineoplastic agent, and, Methotrexate, a chemotherapeutic agent. This study demonstrates the options and alternatives that are available to make Raman spectroscopy suitable for the human bodily fluid analysis in the liquid form, leading to a better accuracy and repeatability and thus a better sensitivity.
Parachalil, D.R. (2019) Screening of Human Serum/Plasma using Vibrational Spectroscopy for Early Disease Diagnostics and Therapeutic Drug Monitoring , Doctoral Thesis, Technological University Dublin. DOI: 10.21427/k6cy-n181