Measuring colloid-surface interaction forces in parallel using fluorescence centrifuge force microscopy

Area of Science:

• Soft Matter Physics
• Colloidal Science
• Biophysics

Background:

• Colloidal interactions are crucial for soft and biological material properties.
• Quantifying these forces often involves measuring colloid-surface interactions.
• Existing centrifuge force microscopes (CFM) have limitations in speed and imaging capabilities.

Purpose of the Study:

• To develop a fluorescence CFM (F-CFM) integrating fluorescence and brightfield microscopy.
• To enable parallel microscale force measurements of colloidal-surface interactions.
• To advance the study of soft and biological materials by correlating force measurements with fluorescence imaging.

Main Methods:

• Development of a fluorescence CFM (F-CFM) operating at up to 5000 RPM.
• Utilized a GoPro camera for real-time video viewing and audio signal analysis for speed correlation.
• Measured detachment forces of colloidal microspheres from a charged glass surface across varying ionic strengths.

Main Results:

• The F-CFM achieved 2.5x higher speeds and 6.25x greater maximum force than previous instruments.
• Successfully measured microscale colloidal-surface interaction forces.
• Force distribution data correlated well with approximated DLVO theory.

Conclusions:

• The F-CFM is a powerful tool for microscale force measurements combined with fluorescence imaging.
• This technology facilitates a deeper understanding of colloidal interactions in soft and biological systems.
• The F-CFM opens new avenues for research in materials science and biophysics.