Shear-driven rolling of DNA-adhesive microspheres

Area of Science:

• Biophysics
• Cellular Mechanics
• Adhesion Dynamics

Background:

• Multivalent cell binding, crucial for processes like leukocyte rolling, involves numerous weak ligand interactions.
• Quantitative modeling of cell rolling has been hindered by incomplete understanding of ligand binding and unbinding kinetics.

Purpose of the Study:

• To develop and validate a cell-free experimental model for studying multivalent ligand-mediated rolling.
• To quantitatively assess the predictive power of adhesive dynamics simulations for particle rolling behavior.

Main Methods:

• Utilized polymer microspheres with DNA strands as ligands to mimic cell adhesion to a surface.
• Employed a cell-free system to control ligand properties and experimental conditions.
• Applied adhesive dynamics simulations to model particle rolling and compare with experimental data.

Main Results:

• Observed robust rolling behavior of microspheres under specific shear rates and DNA ligand properties.
• Adhesive dynamics simulations accurately predicted mean rolling velocity and lateral diffusivity.
• The model also captured variations in velocity within single particle trajectories.

Conclusions:

• Validated the use of DNA-mediated microsphere rolling as a model system for studying cell adhesion.
• Confirmed the quantitative accuracy of adhesive dynamics simulations in capturing complex rolling physics.
• These findings support the extension of these simulation frameworks to more complex biological systems, such as rolling leukocytes.