Actively Driven Fluctuations in a Fibrin Network

Frontiers in Physics

Qingda Hu¹  Tessa Altair Morris¹  Anna Grosberg²  Elliot L. Botvinick³  Alex J. Levine⁴ 

[1] Irvine, CA, United States;Irvine, CA, United States;Irvine, CA, United States;Irvine, CA, United States;Irvine, CA, United States;Irvine, CA, United States;Irvine, CA, United States;Irvine, CA, United States;Irvine, CA, United States;Irvine, CA, United States;Irvine, CA, United States;Irvine, CA, United States;Los Angeles, CA, United States;Los Angeles, CA, United States;Los Angeles, CA, United States;

关键词: fibrin;    fiber;    force transmission;    fluctuations;    optical tweezers;    extracellular matrix;    microrheology;   

DOI  :  10.3389/fphy.2020.568736

来源: Frontiers

【 摘 要 】

Understanding force propagation through the fibrous extracellular matrix can elucidate how cells interact mechanically with their surrounding tissue. Presumably, due to elastic nonlinearities of the constituent filaments and their random connection topology, force propagation in fiber networks is quite complex, and the basic problem of force propagation in structurally heterogeneous networks remains unsolved. We report on a new technique to detect displacements through such networks in response to a localized force, using a fibrin hydrogel as an example. By studying the displacements of fibers surrounding a two-micron bead that is driven sinusoidally by optical tweezers, we develop maps of displacements in the network. Fiber movement is measured by fluorescence intensity fluctuations recorded by a laser scanning confocal microscope. We find that the Fourier magnitude of these intensity fluctuations at the drive frequency identifies fibers that are mechanically coupled to the driven bead. By examining the phase relation between the drive and the displacements, we show that the fiber displacements are, indeed, due to elastic couplings within the network. Both the Fourier magnitude and phase depend on the direction of the drive force, such that displacements typically propagate farther, but not exclusively, along the drive direction. This technique may be used to characterize the local mechanical response in 3-D tissue cultures, and to address fundamental questions about force propagation within fiber networks.

【 授权许可】

CC BY