FLUCS technique manipulates living cells

23 May 2023

Max Planck Institute uses lasers to control position and movement in cells in embryos.

A laser-based technology developed at the Max Planck Institute of Molecular Cell Biology and Genetics (MPI-CBG) could help researchers gather new insight into cell behavior and embryo development.

Named FLUCS, or focused light-induced cytoplasmic streaming, the technique is a photomanipulation method allowing scientists to optically generate and precisely control microscopic flows within cells, embryos and other viscous fluids.

FLUCS has now been licensed to Rapp OptoElectronic, a spin-out specializing in microscopy development, for commercial development.

The goal is to promote FLUCS's use as an additional module for high-resolution microscopes, where it could not only improve cell biological and medical research, but also open up new possibilities in microfluidics.

At present, the targeted manipulation of cells under controlled conditions is a major challenge when studying the processes and causal relationships in cell development, according to MPI-CBG. One common problem with conventional methods is that the sample is disturbed by the manipulation, influencing the end results.

FLUCS allows non-invasive manipulation of cells for the first time, by moderately heating the specimen with a rapidly scanned infrared laser spot and inducing directed fluid flows through local changes in the density and viscosity of the liquid medium. By designing the scan path of the laser, fluid can be directed along desired paths in the focal plane of a microscope.

This causes the biomolecules floating in the cytoplasm to be set in controlled motion without the need for other modification of the sample and while they can still interact freely with their environment, in contrast to other forms of cell manipulation such as the use of optical tweezers.

Understanding which molecules go where

“FLUCS fills a gap in the previously available micro-manipulation techniques to study the causes and consequences of intracellular movement," commented Sven Warnck of Rapp OptoElectronic.

"Directed liquid flows are induced by moderately warming up the sample with a laser spot, and their path can easily be specified individually, for example as a line, circle or free form. In this way cell components such as organelles, proteins and chromatin can be moved freely in the cell nucleus without having to hold or fix them."

For cell biology, cytoplasmic currents created by FLUCS can be used to invert the scaffolding structures termed PAR proteins and hence influence embryonic development. In microfluidics, the behavior of liquid quantities in the micro or picoliter range could be examined in more detail, supporting new methods of quality control or food safety.

In trials at MPI-CBG, FLUCS was used to induce controlled currents in living worm embryos and transport biomolecules to different parts of the growing embryonic system. This redistribution can reveal the importance of cytoplasm movement as the embryos become orientated, and help answer the question of which molecule has to go where during development.

Rapp OptoElectronic is now offering FLUCS as a market-ready product to researchers and industrial customers, with a pilot system available to users in the Light Microscopy Facility of MPI-CBG in Dresden.

"The successful cooperation between the MPI-CBG and Rapp OptoElectronic will bring first-class commercial products to the market that are far superior to the current state of the art," said Bernd Ctortecka, patent and license manager at Max Planck Innovation. "FLUCS makes microscopy interactive and opens up new possibilities for a variety of research areas."