Ultra-sensitive paper-based endotoxin test strips with antibody-enzyme complexes

Overview

This solution delivers a fast, low-cost, and highly sensitive method for detecting endotoxins in solution using paper-based lateral flow test strips combined with antibody-enzyme complexes. Designed for point-of-use operation, the strips require minimal training and provide visual color-change results that can be interpreted using an in-kit reference guide, a companion mobile app, or a portable lateral flow assay (LFA) cassette reader. The technology targets ultra-sensitive detection in the 0.03 to 0.25 EU/ml range, addressing the need for accessible endotoxin monitoring in pharmaceutical manufacturing, clinical diagnostics, water quality testing, and research laboratories where traditional lab-based assays (such as LAL testing) are costly, time-consuming, or require skilled personnel.

Technical specifications

• Detection mechanism: Lateral flow immunoassay using antibody-enzyme complexes that bind to endotoxin components, including O-antigen, oligosaccharide, and phospholipid regions, as well as cross-reactive antibodies with broad lipid-region affinity.
• Antibody types: Both polyclonal and monoclonal antibodies, including lupus anticoagulant and anticardiolipin, selected for high specificity and binding affinity.
• Signal generation: Reporter enzymes cleave dye substrates to produce visible color changes, with intensity correlated to endotoxin concentration.
• Test strip configuration: Three detection zones embedded with the best-performing antibody-enzyme conjugates for semi-quantitative or quantitative readout.
• Sensitivity enhancement: Optional sample concentration via tangential ultrafiltration (e.g., 50 ml syringe with Millipore ultrafiltration system) to achieve ultra-sensitive detection limits.
• Result analysis: In-kit reference guide for visual quantification; mobile app or portable LFA cassette reader for more accurate, detailed digital analysis.
• Platform precedent: Existing antibody-enzyme strip platform validated for pesticide detection (imidacloprid) at 1.0 ppb sensitivity with companion app.

Technology readiness level

The project is at an early-to-mid development stage. The underlying antibody-enzyme lateral flow strip platform has already been demonstrated for pesticide detection at parts-per-billion sensitivity, establishing proof of concept for the core technology. Current work focuses on identifying and validating optimal antibodies against endotoxin targets using isothermal titration calorimetry (MicroCal PEAQ-ITC). Next steps include conjugating the best-performing antibodies to reporter enzymes, embedding them on three-zone test strips, and validating detection limits in the 0.03–0.25 EU/ml range. Integration with a mobile app and portable cassette reader is planned. The technology has not yet been validated against regulatory endotoxin testing standards and will require further clinical or pharmaceutical-grade validation before commercial deployment.