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We invented an optical approach, laser-tracking microrheometry (LTM), to quantify cellular mechanics during pathogen infection. With subnanometer resolution, we can track the Brownian “dancing” of microscopic particles, and frequency-transform analysis of their motions reveals their mechanical microenvironment. In polymeric test materials, LTM is very accurate (<15%) and very fast (~1s) in measuring mechanical properties. LTM provides revolutionary abilities for noninvasive mapping of subcellular mechanical properties. However, quantifying cellular mechanics is meaningless without a deeper understanding of the physics of cytoskeletal polymers, and LTM offers a unique opportunity to develop this understanding.

1.  How do filament length and crosslinking affect mechanical properties? Are there invariant physical signatures for biochemical processes?
2.  How does filament flexibility affect mechanics?
3.  Can we design a generic probe appropriate for all subcellular conditions?