Researchers develop new technology to measure the rotational movement of cells

Forscher entwickeln bahnbrechende Technologie zur Messung der Rotationsbewegung von Zellen

Graphic summary. Recognition: nano letters (2022). DOI: 10.1021/acs.nanolett.2c02232

Mechanics plays a fundamental role in cell biology. Cells control these mechanical forces to explore their environment and learn about the behavior of surrounding living cells. The physical properties of a cell’s environment, in turn, affect cell functions. Therefore, understanding how cells interact with their environment provides crucial insights into cell biology and has wider implications for medicine, including disease diagnosis and cancer therapy.

So far, researchers have developed numerous tools to study the interaction between cells and their 3D microenvironment. One of the most popular technologies is traction force microscopy (TFM). It is a leading method for determining the tensile forces on a cell’s substrate surface and provides important information on how cells perceive, adapt and respond to the forces.

However, the application of TFM is limited to providing information about the translational movement of markers on cell substrates. Information about other degrees of freedom, such as B. rotational motions remain speculative due to technical limitations and limited research on the subject.

Engineering experts from Hong Kong University have proposed a novel technique to measure cell traction force field, filling the research gap. The interdisciplinary research team was led by Dr. Zhiqin Chu from the Faculty of Electrical Engineering and Electronics and Dr. Yuan Lin from the Faculty of Mechanical Engineering. They used single nitrogen vacancy (NV) centers in nanodiamonds (NDs) to propose a linear polarization modulation (LPM) method that can measure both rotational and translational motion of labels on cell substrates.

The study offers a new perspective on measuring the multidimensional cell traction force field and the results have been published in the journal nano letters.

The research demonstrated high-precision measurements of the rotational and translational movement of the markers on the cell substrate surface. These experimental results confirm the theoretical calculations and previous results.

Because of their ultrahigh photostability, good biocompatibility, and convenient surface chemical modification, fluorescent NDs with NV centers are excellent fluorescent labels for many biological applications. The researchers found that based on the measurement results of the relationship between the fluorescence intensity and the orientation of a single NV center to the laser polarization direction, high-precision orientation measurements and background-free imaging could be achieved.

Thus, the LPM method invented by the team helps to solve technical bottlenecks in cellular force measurement in mechanobiology, which includes interdisciplinary collaborations from biology, engineering, chemistry and physics.

“The majority of cells in multicellular organisms are subjected to forces that are highly coordinated in space and time. The development of a multidimensional cell traction force field microscopy was one of the biggest challenges in this field,” said Dr. Chu.

“Compared to traditional TFM, this new technology offers us a new and convenient tool to study the real 3D interaction between cell and extracellular matrix. It helps to achieve both rotational-translational motion measurements in the cell traction field and to provide information about cell traction force,” he added.

The main highlight of the study is the ability to display both translational and rotational movement of markers with high precision. It is a big step towards analyzing mechanical interactions at the cell-matrix interface. It also offers new avenues of research.

Special chemicals on the cell surface cause the cells to interact and bond together as part of a process called cell adhesion. The way a cell generates stress during adhesion has been described primarily as “in plane”. Processes such as traction tension, actin flow, and adhesion growth are all interconnected and exhibit complex directional dynamics.

The LPM method could help to understand the complicated torques surrounding focal adhesion and separate different mechanical loads at the nanoscale (e.g. normal tractions, shear forces). It can also help to understand how cell adhesion responds to different types of stress and how these mediate mechanotransduction (the mechanism by which cells convert mechanical stimuli into electrochemical activity).

This technology also shows promise for studying various other biomechanical processes, including immune cell activation, tissue formation, and cancer cell replication and invasion. For example, T-cell receptors, which play a central role in the immune response to cancer, can generate extremely dynamic forces that are crucial for tissue growth. This high-precision LPM technology can help to analyze these multi-dimensional force dynamics and provide insights into tissue development.

The research team is actively investigating methods to expand optical imaging capabilities and map multiple nanodiamonds simultaneously.

A van der Waals force-based adhesion study of stem cells exposed to cold atmospheric jets

More information:
Lingzhi Wang et al, All-Optical Modulation of Single Defects in Nanodiamonds: Revealing Rotational and Translational Motions in Cell Traction Force Fields, nano letters (2022). DOI: 10.1021/acs.nanolett.2c02232

Provided by the University of Hong Kong

Citation: Researchers develop new technology to measure rotational motion of cells (2022 October 27) Retrieved October 27, 2022 from

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