Dual-Signal Capillary Sensor Based on Viscosity Variation for Bacterial Endotoxin Detection

Area of Science:

• Biomedical Engineering
• Analytical Chemistry
• Biosensing

Background:

• Endotoxin from Gram-negative bacteria is a significant public health threat due to its stability and activity.
• Current endotoxin detection methods require improvement in reliability, speed, and convenience.
• A sensitive and practical detection strategy is crucial for various analytical applications.

Purpose of the Study:

• To develop a novel distance-color dual-signal capillary sensor (DC-CapSensor) for endotoxin detection.
• To utilize viscosity variations induced by endotoxin-Tachypleus Amebocyte Lysate (TAL) interaction for signal generation.
• To establish a rapid, reliable, and convenient method for endotoxin quantification.

Main Methods:

• Fabrication of a capillary sensor incorporating a membrane for distance signal generation.
• Doping the viscous solution with horseradish peroxidase (HRP) for colorimetric signal readout.
• Utilizing the HRP-catalyzed H2O2/TMB reaction, where viscosity modulates residual HRP concentration.
• Employing the cascade reaction between TAL and endotoxin to induce specific viscosity changes.

Main Results:

• The DC-CapSensor demonstrated dual-signal detection based on viscosity-induced variations.
• Achieved low detection limits for endotoxin: 0.0407 EU/mL (distance) and 0.0614 EU/mL (colorimetric).
• Successfully quantified endotoxin levels in commercial glucose and sodium chloride injections.

Conclusions:

• The DC-CapSensor offers a reliable and sensitive method for endotoxin detection using viscosity changes.
• The dual-signal approach enhances discrimination of different viscosities or concentrations.
• This method is promising for practical endotoxin analysis, particularly in simple, low-viscosity matrices.