New research facility allows scientists to watch molecules in action

Rubén Casanova Sáez is loading a sample into the microfluidics unit of the C-Trap instrument.

ImageMattias Pettersson

Sitting in a windowless room, the C-Trap instrument may appear unremarkable at first glance. Yet, its capabilities are very powerful. At its core lies an optical tweezer, two highly focused laser beams capable of trapping tiny particles to which single molecules can attach. The laser beams can hold the molecules steady and their mechanical properties can be analysed while the surrounding is manipulated.

“The C-Trap allows us for example to visualize how a single protein binds to a DNA or RNA molecule that is held in place by the laser traps,” explains Rubén Casanova Sáez who is the manager of the newly established C-Trap Facility at the Umeå Plant Science Centre. “We can monitor how quickly and strongly the protein binds and test how different substances or mechanical forces affect this interaction – all in real time.”

Inside the flow cell, a tiny chamber, molecules and the surrounding liquid flow through narrow channels. Trapping lasers and confocal microscopy opperate inside the flow cell, which makes it possible to manipulate and image single molecules in real time.

ImageMattias Pettersson

New capabilities for studying molecular dynamics

In addition to the optical tweezer, the C-Trap instrument includes a microfluidics unit and a confocal microscope. The microfluidics unit allows researchers to adjust the flow and to rapidly introduce new substances, enabling precise control over the environment around the trapped molecule. At the same time, the confocal microscope captures high-resolution images of the trapped molecule, along with the surrounding molecules as they move and interact with it.

“We can also observe dynamic molecular events such as DNA transcription, where proteins not only bind but also move along the DNA strand,” says Rubén Casanova Sáez. “The C-Trap allows us to measure the speed at which these proteins move, detect where they pause and for how long, and quantify the force they exert on the DNA as they move. It is also ideal for studying how strongly certain molecules interact with cell membrane receptors, or for measuring forces involved in protein folding.”

Using the joystick, the laser beams - shown as a small red circle on the middle screen - are controlled to trap a molecule.

ImageMattias Pettersson

While Umeå University already had facilities for imaging single molecules such as the Biochemical Imaging Centre Umeå and even in-house developed optical tweezers from the Biophysics and Biophotonics group at the Department of Physics, the C-Trap offers new possibilities. What makes it unique is the integration of multiple capabilities, allowing researchers to study molecular mechanisms and mechanical properties in a dynamic real-time setting.

A central tool for advancing research across fields

“This technology is fundamental to a wide range of research fields, including immunology, cell mechanobiology, microbiology, virology, physics and beyond,” adds Rubén Casanova Sáez. “The C-Trap can help answer many different research questions and I am excited to collaborate with researchers from across disciplines. Anyone interested in using the C-Trap, or even just curious about how it might support their research, is welcome to visit the facility’s homepage and contact me.”

PhD student Léa Bogdziewiez (left), one of the first users of the facility, is using the C-Trap to study single-molecule adhesion mechanisms in plant cells.

ImageMattias Pettersson

Currently, three projects are running at the C-Trap Facility, with several more in preparation from departments including Medical Biochemistry and Biophysics, Clinical Microbiology and Physics. Users of the facility receive comprehensive support throughout the process, from experimental design and sample preparation to feedback during data acquisition. Anyone interested can join an introductory training on how to operate the C-Trap and receive support for data analysis and interpretation.

“When we first began setting up the facility, everything seemed challenging,” reflects Rubén Casanova Sáez. “But I was fortunate to receive great support, especially from our C-Trap steering group and its chair Åsa Strand. At this point we are an official KBC facility and have recently been recognised as a research infrastructure at Umeå University. With a growing number of projects and collaborations in future, I hope to see the C-Trap Facility grow into an interdisciplinary research hub at Umeå University.”