Finger-prick whole blood analysis via surface-enhanced Raman spectroscopy using centrifugal silver plasmonic paper substrates.

Authors

Camila Calvani, Stefano Fornasaro, Cicero Cena, Alois Bonifacio

Published in

Analytica chimica acta. Volume 1423. Pages 346161. Nov 15, 2026. Epub Aug 21, 2026.

Abstract

Direct surface-enhanced Raman scattering (SERS) analysis of whole blood remains challenging due to spectral interference from hemoglobin, ergothioneine, and other matrix components, typically requiring sample pre-treatment. Here, Centrifugal Silver Plasmonic Paper (CSPP) is applied for the first time to unprocessed capillary blood collected by finger-prick, generating SERS-active silver nanostructures in situ within the same paper strip used for sampling, thereby eliminating pre-treatment and extraction steps. A multi-factor experimental design was used to disentangle four sources of spectral variability (storage temperature, storage time, spatial position along the strip, and inter-donor variability) analysed via the Linear Mixed Model-Principal Components Analysis (LiMM-PCA) framework.
All modelled effects were statistically significant (permutation test, p < 0.001). Spatial position along the strip, nested within storage condition, was the dominant source of spectral variance (57%), exceeding inter-donor variability (12%), while storage time and temperature contributed modestly but detectably (<2% each). SERS spectra were dominated by ergothioneine and albumin-bound uric acid bands, with an analyte-specific spatial gradient along the strip consistent with a paper-chromatographic separation mechanism driven by centrifugation.
These findings establish CSPP as a robust, reagent-free platform for direct SERS profiling of metabolites in unprocessed capillary blood. The rigorous variance partitioning provided by LiMM-PCA identifies spatial position as the primary factor governing measurement reproducibility, providing a quantitative basis for protocol optimisation. The approach has direct implications for the development of point-of-care and remote biomonitoring devices.

PMID:
42838672
Bibliographic data and abstract were imported from PubMed on 07 Oct 2026.

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