Characterization, detection, and counting of metal nanoparticles using flow cytometry

Area of Science:

• Nanotechnology
• Analytical Chemistry
• Biophysics

Background:

• Accurate detection, characterization, and quantification of nanoparticles in suspensions are crucial.
• Understanding interactions between similar nanoparticle types is essential for scientific advancement.

Purpose of the Study:

• To establish a reference scale using polystyrene (PS) beads for evaluating flow cytometer performance.
• To determine optimal conditions for characterizing metal nanoparticles using flow cytometry, focusing on laser selection and sample concentration.

Main Methods:

• Utilized submicron PS beads (200 nm–1 µm) to calibrate flow cytometer functionality, sensitivity, resolution, and reproducibility.
• Acquired side scatter intensity (SSC) data from metal nanoparticles using both 405 nm and 488 nm lasers.
• Employed 1 µm polystyrene reference beads to manage sample concentration and avoid coincidence counting artifacts during flow cytometry analysis.

Main Results:

• The 405 nm laser provided superior results, yielding smaller coefficient of variation (CVs), reduced SSC, better particle separation, and fewer scatter differences compared to the 488 nm laser.
• Significant artifacts, including electronic overload and altered histogram shapes, occurred with concentrated submicron particles (10^6–10^7 particles/mL).
• Dilution ratios between 1:10,000 and 1:100,000 were necessary for accurate nanoparticle characterization via flow cytometry.

Conclusions:

• Flow cytometry requires precise sample dilution (1:10,000 to 1:100,000) for accurate nanoparticle quantification.
• The 405 nm laser is more effective than the 488 nm laser for characterizing metal nanoparticles by flow cytometry.
• Reference beads are vital for ensuring accurate concentration measurements and reliable flow cytometer performance.