Sepsis, a life-threatening inflammatory response, demands
economical,
accurate, and rapid detection of biomarkers during the critical “golden
hour” to reduce the patient mortality rate. Here, we demonstrate
a cost-effective waveguide-enhanced nanogold-linked immunosorbent
assay (WENLISA) based on nanoplasmonic waveguide biosensors for the
rapid and sensitive detection of procalcitonin (PCT), a sepsis-related
inflammatory biomarker. To enhance the limit of detection (LOD), we
employed sandwich assays using immobilized capture antibodies and
detection antibodies conjugated to gold nanoparticles to bind the
target analyte, leading to a significant evanescent wave redistribution
and strong nanoplasmonic absorption near the waveguide surface. Experimentally,
we detected PCT for a wide linear response range of 0.1 pg/mL to 1
ng/mL with a record-low LOD of 48.7 fg/mL (3.74 fM) in 8 min. Furthermore,
WENLISA has successfully identified PCT levels in the blood plasma
of patients with sepsis and healthy individuals, offering a promising
technology for early sepsis diagnosis.