Electrochemical plasmonic sensing strategy for sensitive detection of gram-negative endotoxin in blood samples

This study presents a proof-of-concept electrochemically modulated surface plasmon wave (EC-SPW) immunosensor for highly sensitive detection of gram-negative endotoxins in whole blood. Our innovative immunosensor uses an electrochemically modulated optical signal from a surface plasmon wave, which is paired with a pre-conjugated redox reporter dye. The biosensor, embedded in a micro-electrochemical flow cell, employs methylene blue as a redox-active probe due to its reversible refractive index changes during redox transitions, which amplify the optical signal for enhanced sensitivity. By integrating our transduction sensing platform with a sandwich bioassay format, we achieve an exceptional detection limit of 0.048 EU/ml for gram-negative endotoxins in whole blood samples. The sensor demonstrates excellent reproducibility and selectivity in complex blood matrices, highlighting its potential for translation to authentic clinical samples. These findings establish the EC-SPW platform as a promising tool for rapid, sensitive, and clinically relevant pathogen detection, paving the way for improved diagnostics in infectious disease management.