Sensing Active Heparin by Counting Aggregated Quantum Dots at Single-Particle Level

Area of Science:

• Biomedical Engineering
• Analytical Chemistry
• Nanotechnology

Background:

• Monitoring heparin levels in blood is crucial for surgical patients.
• Existing heparin detection methods often rely on electrostatic interactions and light signal intensity changes.
• There is a need for more sensitive and selective heparin assays.

Purpose of the Study:

• To develop a novel quantum dot (QD) aggregation-based assay for quantifying heparin.
• To enhance the sensitivity and selectivity of heparin detection in biological samples.

Main Methods:

• Utilized fluorescence QDs modified with anti-thrombin III (AT III) and cationic micelles.
• Developed a QD aggregation strategy triggered by heparin binding.
• Employed spectral imaging fluorescence microscopy to differentiate aggregated QDs from single QDs based on blue shift and photobleaching.

Main Results:

• Established a linear relationship between the ratio of aggregated QD spots and heparin concentration (4.65 × 10^-4 to 0.023 U/mL).
• Achieved a limit of detection of 9.3 × 10^-5 U/mL (∼0.1 nM).
• Demonstrated acceptable recovery of spiked heparin in human plasma samples.

Conclusions:

• The developed QD aggregation assay provides a sensitive and selective method for heparin quantification.
• This assay has potential applications in monitoring heparin levels in clinical settings, particularly during and after surgery.