Direct Quantification of S100β and BNP in Whole Blood via a GHNP-Enhanced SERS Plasmonic Sensor for Ultra-Early Ischemic Stroke Diagnosis and Clinical Stratification

Ischemic stroke (IS) demands ultra-early diagnosis to improve outcomes, yet conventional imaging modalities often fail to capture the critical window for intervention due to inherent temporal delays. Here, we report a surface-enhanced Raman scattering (SERS)-based plasmonic nanosensor that leverages gold hexagonal nanoparticles (GHNPs) as high-efficiency plasmonic amplifiers to enable simultaneous quantification of two key IS biomarkers-S100β and brain natriuretic peptide (BNP)-directly in whole blood. By engineering a sandwich immunoassay on a silver nanoparticle-modified conductive substrate, the GHNPs generate dense plasmonic “hotspots” that substantially amplify Raman signals, allowing for sensitive and stable detection without sample pretreatment. The sensor was validated in a rat middle cerebral artery occlusion (MCAO) model, capturing dynamic biomarker elevations within hours post-ischemia, and in clinical blood samples from IS patients, where biomarker levels were significantly elevated compared to healthy controls. The platform achieved detection limits as low as 7.18 fg/mL for S100β and 8.98 fg/mL for BNP, markedly outperforming conventional ELISA. By enabling rapid, multiplexed, and highly accurate quantification of these two complementary biomarkers, our SERS platform directly addresses the diagnostic gap between biochemical onset and clinical imaging, offering a powerful tool for ultra-early IS diagnosis and clinical stratification with strong potential for translational application.