Metal-free photoinduced ROMP-enabled electrochemical aptasensor for ultrasensitive detection of endotoxin

Accurate diagnosis of Gram-negative bacterial infections hinges critically on endotoxin detection, with ultrasensitive quantification playing a pivotal role in clinical diagnosis, precision therapy, food safety and environmental monitoring. Herein, we pioneer an electrochemical aptasensing platform based on metal-free photoinduced ring-opening metathesis polymerization (MF photo-ROMP) for endotoxin analysis. Specifically, the aptamer is employed for selective capture of endotoxin, whose glycan chain is then modified with 4-formylphenylboronic acid via boronate affinity. This interaction enables anchoring of hundreds of 3-aminopropanol vinyl ether photoinitiators through aldehyde-amine condensation, followed by blue light (λ = 470 nm)-triggered MF photo-ROMP of cyclopentenyldiferrocene (CFc) monomers, generating polymer chains each loaded with over 1,000 electroactive probes for signal amplification. This metal-free system effectively circumvents residual ruthenium catalyst contamination inherent in conventional ROMP, aligning with green chemistry principles. The platform exhibits an ultralow detection limit (0.37 fg/mL) and a broad linear range (1.0 fg/mL to 1.0 ng/mL), coupled with simplicity, high specificity, cost-effectiveness, and exceptional interference resistance. The versatile framework that integrates "aptamer recognition, glycan-targeted modification, and MF photo-ROMP amplification" extends beyond low-abundance endotoxin analysis to ultrasensitive screening of glycoproteins and tumor biomarkers (e.g., AFP, CA19-9), highlighting significant potential for early clinical diagnosis, foodborne endotoxin screening, and environmental microbial monitoring.