Measuring absolute number concentrations of nanoparticles using single-particle tracking.

Area of Science:

• Colloid and Surface Science
• Nanotechnology
• Microscopy Techniques

Background:

• Single-particle tracking (SPT) microscopy is a valuable tool for characterizing nanoparticulate systems.
• Accurate determination of particle number concentration is crucial for understanding and utilizing nanoparticle dispersions.
• Existing methods often require precalibration or are sensitive to image processing parameters.

Purpose of the Study:

• To introduce a novel, calibration-independent method for estimating particle number concentration in Brownian particle dispersions.
• To leverage single-particle tracking (SPT) microscopy for robust concentration measurements.
• To validate the method's accuracy and reliability across different particle sizes and dilutions.

Main Methods:

• Developed a model based on the trajectory length distribution of tracked particles.
• Used the model to estimate the effective detection region volume.
• Applied the method to polymer nanospheres (0.19- and 0.52-μm) in various dilutions.

Main Results:

• The proposed SPT-based method accurately estimates particle number concentration.
• The method is independent of precalibration reference measurements.
• Results showed excellent agreement between experimentally estimated concentrations and those calculated from stock solutions.

Conclusions:

• The developed method provides a robust and accurate approach for determining particle number concentration in dispersions using SPT.
• Its independence from precalibration and robustness to image processing settings enhance its practical applicability.
• This technique offers a significant advancement for nanoparticle characterization and analysis.