Rapid fluorescent detection of bacterial endotoxin using dye-entrapping liposome biosensors

Overview

This solution offers a rapid, sensitive method for detecting bacterial endotoxin, known as lipopolysaccharide (LPS), a key contaminant in pharmaceuticals, medical devices, food, and water. The approach uses specially designed liposomes, which are synthetic nanoparticle spheres made of lipid layers, that act as sponges to capture LPS from a sample. Once captured, the liposomes release fluorescent dye or glucose markers that produce a strong, easily readable signal on simple point-of-care devices similar to home pregnancy tests or blood glucose meters. The technology addresses the need for faster, more accessible endotoxin testing outside of specialized laboratory settings, with potential applications in pharmaceutical quality control, clinical diagnostics, food safety, and environmental monitoring.

Technical specifications

Core mechanism:

• Liposomes are synthetic lipid bilayer nanoparticles that entrap millions of fluorescent or electrochemical marker molecules, providing significant signal amplification.
• The hydrophobic lipid tail of LPS molecules naturally embeds into the liposome's lipid bilayer, while the polysaccharide antigens remain exposed on the outer surface for recognition.
• An aptamer (a short synthetic DNA or RNA strand that binds a specific target) or antibody immobilized on a test strip captures the LPS-loaded liposomes.
• A surfactant is then used to lyse the liposomes, releasing the entrapped fluorescent dye or glucose markers for detection.

Key advantages:

• Up to 400-fold improvement in signal-to-noise ratio compared to direct fluorophore detection.
• Six-fold enhancement over the most sensitive commercially available enzyme-based detection methods.
• Adaptable to both optical (fluorescence) and electrochemical (glucometer-style) readout platforms.
• Compatible with lateral flow assay formats for portable, instrument-free testing.

Development approach:

• Lipid composition will be tailored to optimize LPS binding and orientation.
• Maximum dye or glucose loading will be achieved through optimized entrapment protocols.
• Performance will be validated using limits of detection (LOD), limits of quantification (LOQ), and signal-to-noise (S:N) measurements.

Technology readiness level

This technology is currently at an early-to-mid stage of development. The principal investigator has more than 20 years of experience developing liposome-based detection platforms, including lateral flow assays, microfluidic systems, immunomagnetic separation, and high-throughput laboratory formats. Prior work has demonstrated the underlying liposome entrapment and detection principles with ganglioside-based toxins, which share similar hydrophobic interaction properties with LPS. The next phase of work focuses on adapting this validated approach specifically to LPS capture and integrating it into portable point-of-care device formats. Additional development is needed to optimize lipid formulations for LPS binding, validate performance against standard endotoxin reference methods, and demonstrate reliability across diverse real-world sample types.