Participant-level Raman spectroscopy of circulating EV-enriched fractions reveals distributed spectral differences in ischemic stroke patients
10 affiliations
- 1Department of Physics and Mathematics
- 2University of Eastern Finland (UEF)
- 3School of Pharmacy
- 4University of Eastern Finland
- 5A.I. Virtanen Institute for Molecular Sciences, University of Eastern Finland
- 6Experimental Research Center in Normal and Pathological Aging (ARES), University of Medicine and Pharmacy of Craiova, Strada Petru Rares, Nr. 2, Craiova, Romania, 200349
- 7Chair of Vascular Neurology, Dementia and Ageing Research, Department of Neurology, Essen University Medical School, University of Duisburg-Essen, Hufelandstraße 55, Essen, Germany, 45147
- 8Faculty of Pharmacy, University of Helsinki, Viikinkaari 5 E, Helsinki, Finland, 00790
- 9Pharmaceutical Sciences Laboratory, Åbo Akademi University, Artillerigatan 6A, Turku, Finland, 20520
- 10Department of Chemistry, University of Turku, Henrikinkatu 2, Turku, Finland, FI-20500
Abstract
Raman spectroscopy provides a label-free vibrational profile of extracellularvesicle (EV)-enriched biofluid fractions. Participant-level Raman profiles were obtained from 97 participants with ischemic stroke and 50 controls. After quality control and region-specific normalization, spectra acquired at individual spatial sampling locations were aggregated into a single median spectrum per participant in the fingerprint (734–1788 cm −1 ) and C–H stretching (2451–3197 cm −1 ) regions, so that inference was carried out at the participant rather than the measurement level. The objectives were to characterize participant-level spectral variation, assess exploratory case-control separation, and examine associations with clinical outcomes within the stroke cohort. Participant-level spectra showed 21 reproducible Raman bands and shoulder features associated with lipids, proteins, nucleic acids, and carotenoids. Lipid-associated regions accounted for most of the normalized spectral variance (fingerprint PC1, 75.8%; C–H PC1, 67.1%), a pattern that persisted when PCA was repeated using only spectra from participants with ischemic stroke. All 21 features differed between stroke and control participants after false-discovery-rate correction, with increases and decreases distributed across multiple correlated Raman domains. The primary whole-spectrum partial least-squares discriminant analysis (PLSDA) model gave modest discrimination (balanced accuracy 0.655, 95% CI 0.538–0.771; ROC–AUC 0.711, 95% CI 0.550–0.823; sex-stratified permutation p = 0.005). Within the stroke cohort, no whole-spectrum association survived correction for multiplicity, and Montreal Cognitive Assessment (MoCA) scores gave negative cross-validated R 2 , so the spectra did not support the prediction of cognitive outcome. Participant-level Raman spectroscopy, therefore, identifies reproducible biochemical differences within compositionally complex EV-enriched fractions and identifies lipid-, protein-, nucleic acid-, and carotenoid-associated regions for molecular follow-up in larger, balanced cohorts.
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BibTeX
@misc{nardone2026participantlevel,
title = {{Participant-level Raman spectroscopy of circulating EV-enriched fractions reveals distributed spectral differences in ischemic stroke patients}},
author = {Emanuele Nardone and Nikita Belko and Tuomas Kilpeläinen and Olga Neustroeva and Agnieszka Słowik and Nikolaus Plesnila and Aurel Popa-Wagner and Jacopo Zini and Francesco Piga and Saara Zini and Pia Damlin and Emma Gribchenko and Tarja Malm and Polina Kuzhir},
howpublished = {ChemRxiv},
year = {2026},
month = oct,
doi = {10.26434/chemrxiv.15011020/v1},
url = {https://chemrxiv.org/doi/full/10.26434/chemrxiv.15011020/v1},
note = {CC BY},
}
RIS
TY - UNPB
TI - Participant-level Raman spectroscopy of circulating EV-enriched fractions reveals distributed spectral differences in ischemic stroke patients
AU - Emanuele Nardone
AU - Nikita Belko
AU - Tuomas Kilpeläinen
AU - Olga Neustroeva
AU - Agnieszka Słowik
AU - Nikolaus Plesnila
AU - Aurel Popa-Wagner
AU - Jacopo Zini
AU - Francesco Piga
AU - Saara Zini
AU - Pia Damlin
AU - Emma Gribchenko
AU - Tarja Malm
AU - Polina Kuzhir
PY - 2026
DA - 2026/10/25
PB - ChemRxiv
DO - 10.26434/chemrxiv.15011020/v1
UR - https://chemrxiv.org/doi/full/10.26434/chemrxiv.15011020/v1
AB - Raman spectroscopy provides a label-free vibrational profile of extracellularvesicle (EV)-enriched biofluid fractions. Participant-level Raman profiles were obtained from 97 participants with ischemic stroke and 50 controls. After quality control and region-specific normalization, spectra acquired at individual spatial sampling locations were aggregated into a single median spectrum per participant in the fingerprint (734–1788 cm −1 ) and C–H stretching (2451–3197 cm −1 ) regions, so that inference was carried out at the participant rather than the measurement level. The objectives were to characterize participant-level spectral variation, assess exploratory case-control separation, and examine associations with clinical outcomes within the stroke cohort. Participant-level spectra showed 21 reproducible Raman bands and shoulder features associated with lipids, proteins, nucleic acids, and carotenoids. Lipid-associated regions accounted for most of the normalized spectral variance (fingerprint PC1, 75.8%; C–H PC1, 67.1%), a pattern that persisted when PCA was repeated using only spectra from participants with ischemic stroke. All 21 features differed between stroke and control participants after false-discovery-rate correction, with increases and decreases distributed across multiple correlated Raman domains. The primary whole-spectrum partial least-squares discriminant analysis (PLSDA) model gave modest discrimination (balanced accuracy 0.655, 95% CI 0.538–0.771; ROC–AUC 0.711, 95% CI 0.550–0.823; sex-stratified permutation p = 0.005). Within the stroke cohort, no whole-spectrum association survived correction for multiplicity, and Montreal Cognitive Assessment (MoCA) scores gave negative cross-validated R 2 , so the spectra did not support the prediction of cognitive outcome. Participant-level Raman spectroscopy, therefore, identifies reproducible biochemical differences within compositionally complex EV-enriched fractions and identifies lipid-, protein-, nucleic acid-, and carotenoid-associated regions for molecular follow-up in larger, balanced cohorts.
ER -