Holographic Traction Force Microscopy

TL;DR

This paper introduces a holographic traction force microscopy technique that achieves nanometer-scale resolution in measuring cellular forces on soft substrates, enhancing accuracy over traditional fluorescent methods.

Contribution

The paper presents a novel holographic tracking microscopy approach for TFM, improving displacement resolution and quantifying marker volume fraction limits.

Findings

Achieved nanometer-scale displacement resolution.

Successfully measured 3D force fields exerted by cancer cells.

Demonstrated experimental feasibility of the holographic TFM method.

Abstract

Traction Force Microscopy (TFM) computes the forces exerted at the surface of an elastic material by measuring induced deformations in volume. It is used to determine the pattern of the adhesion forces exerted by cells or by cellular assemblies grown onto a soft deformable substrate. Typically, colloidal particles are dispersed in the substrate and their displacement is monitored by fluorescent microscopy. As with any other fluorescent techniques, the accuracy in measuring a particule's position is ultimately limited by the number of evaluated fluorescent photons. Here, we present a TFM technique based on the detection of probe particle displacements by holographic tracking microscopy. We show that nanometer scale resolutions of the particle displacements can be obtained and determine the maximum volume fraction of markers in the substrate. We demonstrate the feasibility of the technique experimentally and measure the three-dimensional force fields exerted by colorectal cancer cells cultivated onto a polyacrylamide gel substrate.