Sensitive force technique to probe molecular adhesion and structural linkages at biological interfaces

Area of Science:

• Biophysics
• Cell Biology
• Materials Science

Background:

• Cell adhesion and cytoskeletal dynamics are crucial for cell function.
• Molecular-level understanding of cell attachment physical mechanisms and adhesion consequences on material structure is limited.

Purpose of the Study:

• To develop and demonstrate a method for probing physical interactions at soft biological interfaces.
• To quantify molecular adhesion forces and their impact on cell mechanics.

Main Methods:

• Utilized an ultrasensitive transducer (cell-size membrane capsule) coupled with reflection interference microscopy.
• Enabled measurement of submicroscopic displacements (down to 5 nm) under minuscule forces (0.01 pN to 1000 pN).
• Employed a microscopic bead probe with tunable ligand density for controlled cell adhesion and force application.

Main Results:

• Successfully measured local mechanical compliance of cell surfaces with displacement resolution limited by structural fluctuations.
• Demonstrated enhanced detection of molecular adhesion and cytoskeletal activation by monitoring probe position fluctuations at low transducer stiffness.
• Characterized the mechanical response of receptor-substrate linkages during force-driven detachment.

Conclusions:

• The developed system provides unprecedented sensitivity for studying cell-surface interactions at the molecular level.
• This technique offers new insights into the physical mechanisms governing cell adhesion and cytoskeletal rearrangements.
• The findings pave the way for deeper understanding of cell mechanics and material properties in biological systems.