Label-Free Quantification of Molecular Interaction in Live Red Blood Cells by Tracking Nanometer Scale Membrane...

Area of Science:

• Biophysics
• Cell Biology
• Biochemistry

Background:

• Molecular interactions are crucial for cellular functions and drug discovery.
• Existing methods for measuring binding kinetics often require cell extraction and labeling or are limited to fixed cells.
• Live-cell analysis is hindered by noise from cellular micro-motions, complicating in situ measurements.

Purpose of the Study:

• To present a new optical imaging method for quantifying molecular interactions on live red blood cells.
• To measure binding kinetics and cell mechanical properties by tracking membrane fluctuations.
• To explore the heterogeneity of glycoprotein expression on single live cells.

Main Methods:

• Developed an optical imaging technique to track nanometer membrane fluctuations in live red blood cells.
• Measured membrane displacement during glycoprotein-lectin interactions.
• Analyzed data using a thermodynamic model to assess cell elastic properties and binding kinetics.

Main Results:

• Observed reduced membrane fluctuations in fixed cells, indicating fixation alters mechanical properties.
• Determined binding kinetics of glycoprotein to various lectins by tracking single-cell membrane fluctuation amplitude changes.
• Revealed significant differences in binding kinetics and strength, highlighting glycoprotein expression heterogeneity.

Conclusions:

• The developed method enables in situ measurement of molecular interactions and binding kinetics on live cells.
• The findings contribute to understanding cell interaction mechanisms and have potential applications in disease assessment and drug screening.
• This technique offers a new approach for mechanical evaluation of cells and screening of membrane protein-targeting drugs.