An optical aptasensor for real-time quantification of endotoxin: From ensemble to single-molecule resolution

Area of Science:

• Biomedical Engineering
• Nanotechnology
• Analytical Chemistry

Background:

• Endotoxins are potent pyrogens requiring accurate and efficient detection methods.
• Current endotoxin detection assays are often laborious, time-consuming, and unsustainable.
• There is a critical need for rapid, sensitive, and reliable endotoxin monitoring systems.

Purpose of the Study:

• To develop a novel aptamer-based biosensor for real-time optical detection of endotoxin.
• To leverage gold nanoparticles and aptamer conformational changes for sensitive endotoxin sensing.
• To demonstrate the sensor's capability in both ensemble and single-particle detection modes.

Main Methods:

• Utilized aptamer-conjugated gold nanoparticles (AuNPs) coupled to a gold nanofilm for distance-dependent scattering.
• Employed dark-field illumination for optical detection in ensemble and single-particle modes.
• Integrated a microspectrometer for ensemble measurements and a color camera for single-particle analysis.

Main Results:

• The biosensor demonstrated high specificity, reliability, and reusability for endotoxin detection.
• Achieved a linear concentration-to-signal profile in a logarithmic scale in ensemble mode.
• Successfully detected individual endotoxins with single-molecule resolution by monitoring single AuNP color changes.

Conclusions:

• The aptamer-based biosensor provides a sensitive, real-time optical method for endotoxin detection.
• The platform offers both ensemble and single-molecule detection capabilities, enhancing analytical flexibility.
• This technology holds significant potential for advancing safety monitoring in medical, food, and pharmaceutical industries.