CE42 - Capteurs, instrumentation

High-resolution traction force microscopy – Hi-Trac

Traction force microscopy for bacteria

This project aims to develop tools for measuring the forces exerted by bacteria adhering to solid surfaces, in order to better understand the influence of the mechanical environment on the development of biofilms.

How do bacteria sense and respond to their mechanical environment?

Pathogenic bacteria such as P. Aeruginosa (studied in this project) are able to colonize any biotic or abiotic substrate, but the mechanical environment (substrate rigidity, surrounding flow) appears to modulate how they achieve this. The aim of this project is to develop extremely sensitive force sensors to detect forces exerted by bacteria on their environment and better understand how they sense and integrate the mechanical information around them.

The project combines the development of innovative substrates for the measurement of tensile forces with relevant optical techniques, in order to overcome the current limits of resolution, both spatial and amplitude.

Initially, an important work has been carried out to determine the critical parameters to be considered for the design of the substrates (rigidity, chemical nature) from surface colonization experiments. Now that these specifications have been established, the team is exploring their realization.

The production of substrates allowing to quantify the forces exerted by bacterial cells should find a wealth of applications in microbiology, and more generally in cell biology, where the mechanical environment is known to strongly influence the cellular response via mechanotransduction mechanisms. .

2 publications are currently in preparation, and will soon be available on BioArxiv.

Mechanical forces are known to play a critical role in cell biology: cells sense and respond to their microenvironment by applying forces on their surrounding. Measuring and mapping cell-generated forces is thus drawing and ever increasing interest. Traction force microscopy (TFM) is a choice technique allowing such measurements, which consists in mapping optically the surface displacements of a soft substrate of known mechanical properties onto which cells adhere. Still, TFM requires technical expertise that limits its use in cell biology labs. Moreover, TFM currently lacks the sensitivity and spatial resolution that would allow for accurate measurements at a scale smaller than adhesive structures of eukaryotic cell, or for studies of bacteria adhesion (i.e. small cells exerting low-level forces).
In this context, we aim to design robust, simple methods for high-resolution TFM, pushing further the sensitivity, ease-of-use and field of application of the technique. We will rely on two types of innovative, versatile hydrogel-based substrates created using polymer chemistry and light patterning. In combination with well-established classical or super resolution imaging methods, they will provide an unprecedented force sensitivity and 200-500nm spatial resolution, while simplifying the process of force retrieval from the measured displacement field. Following optimization of the chemistry of the substrates and benchmarking of their mechanical response, we will demonstrate their use on individual bacteria. Beside the major advances that such high-resolution TFM tools are expected to provide regarding the fundamental understanding of cell mechanosensing/transduction, the proposed methods are well suited for product development and we plan to patent them and initiate technology transfer in the course of the project.

Project coordination

Delphine Débarre (Laboratoire Interdisciplinaire de Physique)

The author of this summary is the project coordinator, who is responsible for the content of this summary. The ANR declines any responsibility as for its contents.

Partner

LIPHY Laboratoire Interdisciplinaire de Physique

Help of the ANR 302,753 euros
Beginning and duration of the scientific project: January 2020 - 48 Months

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