Vibrational spectroscopic analysis of peripheral blood plasma of patients with Alzheimer’s disease

• Published in: Analytical and bioanalytical chemistry Vol. 407; no. 25; pp. 7747 - 7756
• Main Authors: Carmona, Pedro, Molina, Marina, López-Tobar, Eduardo, Toledano, Adolfo
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01-10-2015; Springer; Springer Nature B.V
• Subjects: Alzheimer disease; Alzheimer Disease - blood; Alzheimer Disease - diagnosis; Alzheimer's disease; Analytical Chemistry; Biochemistry; Biomarkers; Blood plasma; Blood Proteins - chemistry; Brain research; Characterization and Evaluation of Materials; Chemistry; Chemistry and Materials Science; Diagnosis; Diagnostic systems; Discriminant Analysis; Enrichment; Food Science; globulins; Health aspects; Humans; Infrared spectroscopy; Laboratory Medicine; Medical screening; Methods; Monitoring/Environmental Analysis; Mycotoxins; Patients; Peptides; Phlebotomy; Plasma; Plasma - chemistry; Plasma composition; protein secondary structure; Protein Structure, Secondary; Proteins; Raman spectroscopy; Research Paper; ROC Curve; Sensitivity and Specificity; Spectra; Spectrophotometry, Infrared - methods; Spectroscopy; Spectrum Analysis, Raman - methods; Stable isotopes; Madrid Spain; Spain; Infrared spectroscopy; Alzheimer’s disease; Raman spectroscopy; Blood plasma
• ISSN: 1618-2642; 1618-2650
• DOI: 10.1007/s00216-015-8940-7

Using Raman and infrared spectroscopy, we monitored spectral changes occurring in the blood plasma of patients with Alzheimer’s disease (AD) in relation to healthy controls. The protein secondary structure as reflected by amide I band involves β-sheet enrichment, which may be attributable to Aβ peptide formation and to increasing proportion of the globulins that are β-sheet rich. Likewise, the behavior of the infrared 1200–1000–cm⁻¹ region and the Raman 980–910- and 450–400-cm⁻¹ regions can be explained in terms of the said plasma composition change. Further, the 744-cm⁻¹ Raman band from healthy control plasma shows frequency upshifting in the course of AD, which may be generated by the platelets collected in blood plasma. Linear discrimination analysis and receiver operating characteristic (ROC) analysis have been used to distinguish between patients with AD and age-matched healthy controls with a diagnostic accuracy of about 94 %. Graphical Abstract ROC assessment of sample classifications by Raman spectroscopy (dashed line) and linear combination of infrared and Raman spectroscopies (solid line)