Enabling quantification of protein concentration in human serum biopsies using attenuated total reflectance – Fourier transform infrared (ATR-FTIR) spectroscopy

Katie Spalding, Franck Bonnier, Clément Bruno, Hélène Blasco, Ruth Board, Isabelle Benz-de Bretagne, Hugh J. Byrne, Holly J. Butler, Igor Chourpa, Pretheepan Radhakrishnan, Matthew J. Baker*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

47 Citations (Scopus)
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Abstract

Changes in protein concentrations within human blood are used as an indicator for nutritional state, hydration and underlying illnesses. They are often measured at regular clinical appointments and the current analytical process can result in long waiting times for results and the need for return patient visits. Attenuated total reflectance – Fourier transform infrared (ATR-FTIR) spectroscopy has the ability to detect minor molecular differences, qualitatively and quantitatively, in biofluid samples, without extensive sample preparation. ATR-FTIR can return an analytical measurement almost instantaneously and therefore could be deemed as an ideal technique for monitoring molecular alterations in blood within the clinic. To determine the suitability of using ATR-FTIR spectroscopy to enable protein quantification in a clinical setting, pooled human serum samples spiked with varying concentrations of human serum albumin (HSA) and immunoglobulin G (IgG) were analysed, before analysing patient clinical samples. Using a validated partial least squares method, the spiked samples (IgG) produced a linearity as high as 0.998 and a RMSEV of 0.49 ± 0.05 mg mL−1, with the patient samples producing R2 values of 0.992 and a corresponding RMSEV of 0.66 ± 0.05 mg mL−1. This claim was validated using two blind testing models, leave one patient out cross validation and k-fold cross validation, achieving optimum linearity and RMSEV values of 0.934 and 1.99 ± 0.79 mg mL−1, respectively. This demonstrates that ATR-FTIR is able to quantify protein within clinically relevant complex matrices and concentrations, such as serum samples, rapidly and with simple sample preparation. The ability to provide a quantification step, along with rapid disease classification, from a spectroscopic signature will aid clinical translation of vibrational spectroscopy to assist with problems currently faced with patient diagnostic pathways.

Original languageEnglish
Pages (from-to)50-58
Number of pages9
JournalVibrational Spectroscopy
Volume99
Early online date1 Sept 2018
DOIs
Publication statusPublished - 30 Nov 2018

Funding

The authors would like to acknowledge funding from the Postgraduate and Early Career Researcher Exchanges (PECRE) and the Pool Engagement in European Research (PEER) schemes , as well as support from Rosemere Cancer Foundation and the Spectral Analytics Laboratory, University of Strathclyde. Appendix A

Keywords

  • attenuated total reflection
  • clinical
  • infrared
  • protein
  • quantification
  • serum

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