Quantitative measurement of quantum dot uptake at the cell population level using microfluidic evanescent-wave-based...

Area of Science:

• Biotechnology
• Cell Biology
• Nanotechnology

Background:

• Intracellular nanoparticle uptake is crucial for applications like drug delivery and medical imaging.
• Confocal imaging, commonly used, is limited to small cell samples and lacks quantitative population data.
• Traditional flow cytometry cannot resolve subcellular dynamics of nanoparticle entry.

Purpose of the Study:

• To develop and validate a microfluidics-based total internal reflection fluorescence flow cytometry (TIRF-FC) method.
• To quantitatively analyze the initial intracellular uptake and subcellular movement of quantum dots (QDs) at the single-cell level.
• To overcome the limitations of existing imaging techniques for nanoparticle uptake studies.

Main Methods:

• Utilized microfluidics for high-throughput cell handling.
• Employed total internal reflection fluorescence (TIRF) microscopy to focus on the cell membrane vicinity.
• Integrated TIRF with flow cytometry (FC) for single-cell, quantitative analysis of QD uptake.
• Achieved analysis rates of approximately 200 cells per second.

Main Results:

• Demonstrated the capability of TIRF-FC to examine initial QD entry into cells.
• Revealed subcellular QD movement within approximately 100 nm of the cell membrane.
• Quantitatively analyzed QD transport dynamics in large cell populations.
• Observed a decrease in membrane-proximal fluorescence post-dosage due to QD translocation into the cytosol.

Conclusions:

• TIRF-FC is a powerful tool for quantitative analysis of nanoparticle uptake and subcellular dynamics.
• The method provides high-resolution, high-throughput data on nanoparticle-cell interactions.
• QD transport into the cytosol from the membrane vicinity is rapid.