Applications of optical tweezers

Cell motility and cell
motion force dynamics

Study cell motility of sperm cells, flagellated bacteria or other microswimmers and quantify the cell motion force dynamics governing their movement with SENSOCELL optical tweezers.

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Cell motility and cell motion force quantification

SENSOCELL optical tweezers can track the movement of motile cells, measuring forces generated by the cell during active movement. Each cell can be individually analyzed for its mechanical properties and motility behavior.

How to perform cell motility studies with SENSOCELL

Explore the dynamics of cell motility using SENSOCELL optical tweezers and quantify cell motion forces using its calibration-free force spectroscopy module. Additionally, the built-in active microrheology routine in SENSOCELL allows measuring the medium viscosity and study its influence on your cell motility assays.

Trapping the target cells

Optical tweezers can trap and hold one or multiple target cells, using one optical trap per cell.

Real-time force detection

SENSOCELL’s force detector provides dynamic, real-time data of the forces applied on eah cell preventing them to escaping their respective optical trap.

Analyzing data

Forces measured in the XY plane help elucidate complex cell motility behaviors, such as oscillatory force dynamics. Additionally, the instrument provides valuable data in the frequency domain for thermodynamic studies.

Selected publications:

APS Journals

Phys. Rev. E (2021)

Corbyn Jones, Mauricio Gomez, Ryan M. Muoio, Alex Vidal, Anthony Mcknight, Nicholas D. Brubaker, Wylie W. Ahmed.

Stochastic force dynamics of the model microswimmer Chlamydomonas reinhardtii: Active forces and energetics.

Sensocell case studies

Cell motion force dynamics of microswimmer Chlamydomonas reinhardtii

This application example is part of a work from Wylie Ahmed’s Lab (Toulouse University). In this work, the authors demonstrate direct measurement of cell motion forces generated by Chlamydomonas microswimmers and interpreted their motion dynamics using simulations of self-propelled particles.

For this purpose, the authors used a custom optical trapping instrument designed by Impetux to experimentally measure the stochastic force dynamics of a Chlamydomonas microswimmer. Force measurements were performed using our light momentum based force spectroscopy module. Analyzing force and active energy spectrum data of a swimming Chlamydomonas and following a thermodynamic approach, the authors quantified the non-equilibrium activity of the microswimmer.

The authors show that Chlamydomonas exhibit complex oscillatory force dynamics with magnitude of tens of pNs, and rotational dynamics of 1-2 Hz, with an an average power dissipation of approximately 5 fW.

 
Related applications:
Intracellular rheology
Dynamics of an E. coli active colloid bath
CONCEPTS / ADVANTAGES

Key concepts & Advantages

Key concepts

  • Cell Motion: The movement of cells from one location to another, which can be either active (due to the cell’s own mechanisms) or passive (due to external forces).

 

  • Cell Motility: The ability of cells to actively move and navigate their environment using energy-driven processes.

 

  • Microswimmer: A microscopic organism or synthetic particle capable of self-propulsion in a fluid environment, often studied to understand locomotion at small scales, such as bacteria, sperm cells, or engineered nano-robots.

Advantages

  • DIrect Force measurements: SENSOCELL’s direct force sensor enables the measurement of forces applied to cells without requiring prior calibration.

 

  • Sensitivity: SENSOCELL can measure very small forces in the picoNewton (pN) range up to several hundreds of pN, which is ideal for detecting motion forces of microswimmers.

 

  • Cell viability: optical tweezers are minimally invasive, reducing potential damage to the cells and assuring cell viabiility throughout the experiment.

 

  • Temporal resolution: the ability to measure forces in real-time at high temporal resolution provides dynamic insights into the processes governing cell motility.

Conclusions

The extensive trapping and force detection capabilities of SENSOCELL optical tweezers enable the simultaneous measurement of cell motion forces for multiple microswimmers, regardless of their shape and size, thus making it an ideal tool for cell motility assays.

Video 1

Confocal video showing a DVA neuron Ca2+ ion channel activity in a dynamic optical trapping assay. The pulling rate applied to the membrane tether is progressively increased. Scale bar = 5µm. Acquired at 10Hz.

Fig. 1

Time dependence of trap position (top), force signal (middle) and Ca2+ fluorescence signal (bottom) recorded during a membrane tether pulling experiment. The force and Ca2+ ion channel activity signals exhibit negative correlation.

Fig. 2

Force and displacement data for two beads stimulated at frequencies of 4 Hz and 0.25 Hz. The progressive reduction of the beads displacement is in concomitancy with an increase of the applied force and loading rate.

Fig. 1

Schematic representation of the optical tweezers experiment. A fibronectin-coated bead is trapped, brought into contact with the cell membrane and stimulated with oscillations at different frequencies.

Fig.2

Time dependence of trap 1 and trap 2 position (top) and force (bottom) data along the different steps of the described dual tether pulling experiment.

Fig.1

Confocal video of the described dual tether pulling assay performed on a neuron axon. Courtesy of M. Krieg lab (ICFO).

Fig. 1

Time dependence of trap position (top), force signal (middle) and Ca2+ fluorescence signal (bottom) recorded during a membrane tether pulling experiment. The force and Ca2+ ion channel activity signals exhibit negative correlation.