Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Laser propelled cells

02.10.2013
A new tool enables biomechanical studies of individual cells: Red blood cells were laser-propelled over long distances through optofluidic photonic crystal fibers and their deformation due to shear forces monitored.

More than 40 years ago, the foundation for optical tweezers was laid when Arthur Ashkin demonstrated that near the focus of a laser beam, momentum transfer between light and dielectric particles creates gradient forces large enough to pull the particle into the center of highest intensity and scattering forces that push it in the propagation direction of the beam.



Optical trapping of microparticles and cells can be established either by balancing the axial forces of two weakly-focused counter-propagating beams or by using a single tightly focused laser beam. These optical tweezers have developed into an important tool in cell biological research. Optical tweezers can be used not only to fix cells during manipulation but also to investigate the interconnection of a cell’s elasticity to its physiology: healthy and diseased cells differ notably in their mechanical responses, prominent examples being blood disorders, asthma and cancer.

Researchers from Max Planck Institute for the Science of Light, Erlangen, Germany now report a new tool for biomechanical studies of individual cells: Single red blood cells were laser-propelled through stationary liquid in a microfluidic channel over distances of up to 24 cm. Shear forces on the cell surface result in its deformation. This causes changes in speed that can conveniently be monitored using a non-imaging laser Doppler-velocimetric technique. Numerical simulations allowed the scientists to derive the optical force acting on different cell shapes.

The unique method is based on a liquid-filled hollow-core photonic crystal fiber which provides low-loss light guidance in a well-defined single mode, resulting in highly uniform optical trapping and propulsive forces in the core which at the same time acts as a microfluidic channel. Cells are trapped laterally at the center of the core, several microns away from the glass interface, which eliminates adherence effects and external perturbations.

Dynamic changes in velocity at constant optical powers up to 350 mW indicated stress-induced changes in the shape of the cells, which was confirmed by bright-field microscopy. The deformations in the moving cells were not only due to heating. Even at moderate temperature, notable deformations could be detected, especially for osmotically swollen red blood cells.

Interestingly, the deformations occur over timescales of minutes which is rather slow compared to other cell rheological techniques. Re-arrangements of the cytoskeleton might be involved.

The scientists are currently aiming at studying suspended eukaryotic (cancer) cells. These cells are typically ellipsoidal in shape and more rigid than red blood cells, which prevents them from undergoing peculiar changes in shape.

Simulations of the optical forces would be possible, allowing for a complete theoretical analysis of the system. Beyond that, the method may find applications in on-chip cell transport. Cells might be held stationary against a mild counterflow carrying precise amounts of medical drugs.

Moreover, cell-cell interactions between suspended cells might be studied. (Text contributed by K. Maedefessel-Herrmann)

Unterkofler, S., et al; J. Biophotonics 6(9), 743-752 (2013); DOI http://dx.doi.org/10.1002/jbio.201200180

Journal of Biophotonics publishes cutting edge research on interactions between light and biological material. The journal is highly interdisciplinary, covering research in the fields of physics, chemistry, biology and medicine. The scope extends from basic research to clinical applications. Connecting scientists who try to understand basic biological processes using light as a diagnostic and therapeutic tool, the journal offers a platform where the physicist communicates with the biologist and where the clinical practitioner learns about the latest tools for diagnosis of diseases. JBP offers fast publication times: down to 20 days from acceptance to publication. Latest Journal Impact Factor (2012): 3.099 (ISI Journal Citation Reports 2012)

Regina Hagen
Journal Publishing Manager, Journal of Biophotonics
Managing Editor, Physical Sciences
Global Research
Wiley-VCH Verlag GmbH & Co. KGaA
Rotherstrasse 21
10245 Berlin
Germany
T +49 (0)30 47 031 321
F +49 (0)30 47 031 399
jbp@wiley.com
www.biophotonics-journal.org
www.wileyonlinelibrary.com

Regina Hagen | Wiley-VCH
Further information:
http://www.wiley.com

More articles from Life Sciences:

nachricht BigH1 -- The key histone for male fertility
14.12.2017 | Institute for Research in Biomedicine (IRB Barcelona)

nachricht Guardians of the Gate
14.12.2017 | Max-Planck-Institut für Biochemie

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Long-lived storage of a photonic qubit for worldwide teleportation

MPQ scientists achieve long storage times for photonic quantum bits which break the lower bound for direct teleportation in a global quantum network.

Concerning the development of quantum memories for the realization of global quantum networks, scientists of the Quantum Dynamics Division led by Professor...

Im Focus: Electromagnetic water cloak eliminates drag and wake

Detailed calculations show water cloaks are feasible with today's technology

Researchers have developed a water cloaking concept based on electromagnetic forces that could eliminate an object's wake, greatly reducing its drag while...

Im Focus: Scientists channel graphene to understand filtration and ion transport into cells

Tiny pores at a cell's entryway act as miniature bouncers, letting in some electrically charged atoms--ions--but blocking others. Operating as exquisitely sensitive filters, these "ion channels" play a critical role in biological functions such as muscle contraction and the firing of brain cells.

To rapidly transport the right ions through the cell membrane, the tiny channels rely on a complex interplay between the ions and surrounding molecules,...

Im Focus: Towards data storage at the single molecule level

The miniaturization of the current technology of storage media is hindered by fundamental limits of quantum mechanics. A new approach consists in using so-called spin-crossover molecules as the smallest possible storage unit. Similar to normal hard drives, these special molecules can save information via their magnetic state. A research team from Kiel University has now managed to successfully place a new class of spin-crossover molecules onto a surface and to improve the molecule’s storage capacity. The storage density of conventional hard drives could therefore theoretically be increased by more than one hundred fold. The study has been published in the scientific journal Nano Letters.

Over the past few years, the building blocks of storage media have gotten ever smaller. But further miniaturization of the current technology is hindered by...

Im Focus: Successful Mechanical Testing of Nanowires

With innovative experiments, researchers at the Helmholtz-Zentrums Geesthacht and the Technical University Hamburg unravel why tiny metallic structures are extremely strong

Light-weight and simultaneously strong – porous metallic nanomaterials promise interesting applications as, for instance, for future aeroplanes with enhanced...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

See, understand and experience the work of the future

11.12.2017 | Event News

Innovative strategies to tackle parasitic worms

08.12.2017 | Event News

AKL’18: The opportunities and challenges of digitalization in the laser industry

07.12.2017 | Event News

 
Latest News

New type of smart windows use liquid to switch from clear to reflective

14.12.2017 | Physics and Astronomy

BigH1 -- The key histone for male fertility

14.12.2017 | Life Sciences

Guardians of the Gate

14.12.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>