Exploratory Serum-Based Surface-Enhanced Raman Spectroscopy Analysis in Crohn's Disease: A Pilot Cross-Sectional Study.

Crohn's disease (CD) is a chronic inflammatory bowel disease requiring accurate and timely diagnosis. Current diagnostic tools may be invasive, costly, or insufficiently specific. Surface-enhanced Raman spectroscopy may enable rapid, minimally invasive detection of disease-associated biochemical alterations in serum. This cross-sectional pilot study included age- and sex-matched patients with Crohn's disease and healthy controls. Serum samples were analyzed using surface-enhanced Raman spectroscopy. Spectral data were preprocessed and analyzed using principal component analysis-linear discriminant analysis and partial least squares-discriminant analysis. Classification performance was evaluated using leave-one-out cross-validation. Variable importance in projection scores was used to identify discriminatory vibrational bands. Fifty-four participants fulfilled the clinical inclusion criteria, while 51 participant-level spectra were retained for final classification analysis. PCA-LDA differentiated CD from healthy controls with a sensitivity of 85.19%, specificity of 91.67%, accuracy of 88.24%, and AUC of 0.881. PLS-DA showed slightly higher performance, with a sensitivity of 88.89%, specificity of 95.83%, accuracy of 92.16%, and AUC of 0.937. Relevant discriminatory bands were observed at 498, 639, 728, 813, 1136, 1205, 1443, 1579, and 1657 cm-1, suggesting alterations in purine metabolism, protein structure, lipid composition, and nucleic acid-associated signals. Serum-based SERS combined with multivariate analysis showed promising ability to distinguish patients with CD from healthy controls in this pilot cohort. Larger multicenter studies are required to validate these findings and assess clinical applicability.