For a brief introduction to the ideas of microrheology and particle tracking, go here!
For a brief introduction to the ideas of microrheology and particle tracking, go here!
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Graph1: One-point vs. distinct mean squared displacement (m.s.d.) for 1 mg/mL F-Actin with 1 micron beads. The solid red squares is the ensemble averaged m.s.d. for individual bead motions. The open red squres is the distinct m.s.d. obtained from the pairwise correlated motion of beads. Notice that the one-point msd has a definite plateau while the distinct msd follows a power law of 0.5. Graph 2: The m.s.d. from above are interpreted as viscoelastic moduli. Elastic moduli are solid; loss moduli are open. In black are the moduli obtained from a conventional rheometer (courtesy of the Sackmann lab in Muich) In blue are the moduli obtained from one-point microrheology. In red, the moduli from two-point microrheology are shown. Note that these correspond much closer to macroscopic results than one-point results
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| Microenvironments:
We explain the differences between the 1- and
2-point rheology due to microenvironments that the beads experience.
This shows that we can not always assume Case I where there is perfect
coupling between the bead and the network, but have to consider the effects
of a depletion region, bead surface chemistry and size relative to the
mesh of the network. For 1 mg/mL, the average mesh spacing is 300
nm.
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Most recently we've begun a collaboration with
Paul
Matsudaira's lab at MIT to examine the one- and two- point rheology
of actin networks
with an added bundling protein, scruin.
This web page is maintained by:
Margaret
Gardel
9 Oxford Street
McKay Laboratory
Cambridge, MA 02138
617-495-3705
gardel@physics.harvard.edu