Ultrasensitive electrochemical sensor for lipopolysaccharide detection catalyzed by perylene-3,4,9,10-tetracarboxylic acid diimide

Abstract

Background

Lipopolysaccharide (LPS), a bacterial endotoxin prevalent in Gram-negative pathogens (e.g., Escherichia coli), induces severe immune responses linked to endotoxemia and hepatitis. Despite its clinical significance, conventional LPS detection methods (e.g., limulus amebocyte lysate assays) face challenges including operational complexity, high cost, and limited sensitivity. Addressing these limitations necessitates the development of innovative strategies for ultrasensitive LPS quantification.

Results

We present an electrochemical biosensor integrating dual-signal amplification: (1) affinity amplification via phenylboronic acid-cis-diol covalent binding on LPS polysaccharide chains, and (2) photocatalytic amplification using perylene diimide (PDI)-mediated atom transfer radical polymerization (Photo-ATRP) under red light (615-650 nm). Thiol-functionalized DNA aptamers enable specific LPS capture, while PDI catalyzes rapid ferrocene monomer polymerization, achieving exponential signal enhancement. The sensor demonstrates exceptional performance: (1) Ultrahigh sensitivity: Detection limit of 0.25 fg/mL (S/N = 3). (2) Wide dynamic range: Linear response from 1.0 fg/mL to 0.1 pg/mL (R² = 0.998). (3) Robust specificity: Minimal interference in human serum matrices.

Significance

This work establishes a paradigm for LPS detection through three key advances: (1) Operational simplicity: Eliminates enzymatic/nanomaterial dependencies via metal-free PDI photocatalysis. (2) Translational utility: Serum compatibility supports clinical diagnostics and point-of-care applications. (3) Catalytic innovation: Validates PDI as a high-efficiency photocatalyst for controlled polymer synthesis. The sensor’s low-cost fabrication, rapid response (<4.5 h), and femtomolar sensitivity position it as a transformative tool for sepsis monitoring and biomedical research.