Making Hidden Cell Particle Interactions Visible by Thermal Noise Frequency Decomposition.

Area of Science:

• Biophysics
• Cell Biology
• Nanotechnology

Background:

• Thermal noise influences cellular structures, bacteria, and viruses across various scales.
• Particle interactions with the cellular environment can be subtle and difficult to detect, leading to misunderstandings of binding behavior.

Purpose of the Study:

• To demonstrate a method for visualizing previously hidden particle interactions at the cell periphery.
• To analyze particle fluctuations and viscoelastic properties of cellular structures.

Main Methods:

• Utilizing MHz interferometric thermal noise tracking and frequency decomposition.
• Analyzing particle fluctuations in radial and lateral directions using a viscoelastic modulus G(ω,t_ex).
• Employing a spectral update rate of 0.5 s to capture dynamic changes.

Main Results:

• Revealed a similar, frequency-dependent viscoelastic response across different cell types.
• Successfully detected the stiffening of macrophage filopodia tips within 2 s.
• Quantified the extent and stiffness of the cell glycocalyx, which is typically invisible on longer timescales.

Conclusions:

• High-speed particle motion tracking can uncover hidden cellular interactions and binding behaviors.
• The developed method provides insights into molecular-scale elasticity and damping within cells.
• This technique offers a novel approach to studying dynamic cellular processes and interactions.