Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Bioimaging: Aim for the stars

26.10.2012
Glucose–amine rings turn star-shaped fluorescent dyes into powerful probes for imaging cancer cells in three dimensions.

Early detection of soft-tissue diseases, such as breast cancer, typically requires invasive biopsies. Now, a new self-assembled nanoparticle developed by Bin Liu at the A*STAR Institute of Materials Research and Engineering and co-workers may soon make biopsies obsolete.


A new fluorescent glucose-amine probe can make identification of cancer cells (green) using two-photon microscopy easier and safer. © 2012 Guan Wang

The team’s material significantly enhances the safety of two-photon microscopy (TPM) — a technique that uses fluorescent probes to generate three-dimensional pictures of cancer cell structures in living tissue.

Although TPM provides deep access to cell tissue without significant photo-damage, finding suitable substances to act as light-emitting probes is challenging. ‘Quantum dots’ made from nanoscale aggregates of elements such as cadmium and selenium are excellent cell-structure illuminators, thanks to their bright and stable fluorescence. However, their inherent toxicity restricts many possible biological applications.

Liu and her team therefore turned to conjugated organic molecules to produce less toxic dyes for TPM. While such small organic molecules are normally unable to absorb sufficient amounts of laser light to initiate fluorescence imaging, the team resolved this problem by synthesizing a star-shaped material known as a dendrimer. Consisting of a central triphenyl amine core and three ‘arms’ made from extended conjugated chains, this unique geometry can induce much larger cross sections that can absorb two-photons better than isolated fluorescent dyes.

To ensure biocompatibility between the star-shaped dendrimer and cell tissue, the researchers had to employ a chemical trick. Inspired by the versatile binding behavior of chitosan, a natural polysaccharide, the team used a mild bromide–thiol reaction to attach several glucose–amine sugar rings to the dendrimer’s arms. According to Liu, this process lowered the cytotoxicity of the dye and enabled them to functionalize it with folic acid ligands that target the surfaces of a breast cancer cell line known as MCF-7.

The team’s experiments showed that the dendritic dye self-assembled into dispersed nanoparticles when submerged in water — a form that increases two-photon-absorption cross sections and provides a high yield of laser-induced fluorescence. When they incubated these nanoparticles into the MCF-7 cells, subsequent TPM imaging revealed a bright fluorescence localized inside the cancer cell cytoplasma (see image). This data indicates that specific binding occurs between the dendritic dye and folate receptors on the MCF-7 surface.

Cell viabilities close to 100% at dye concentrations used for imaging studies confirms that this strategy is a safe and promising way to increase the use of TPM imaging. “We are keen to expand the current in vitro imaging to in vivo applications,” notes Liu.
The A*STAR-affiliated researchers contributing to this research are from the Institute of Materials Research and Engineering

References

Wang, G., Zhang, X., Geng, J., Li, K., Ding, D. et al. Glycosylated star-shaped conjugated oligomers for targeted two-photon fluorescence imaging. Chemistry – A European Journal 18, 9705–9713 (2012).

A*STAR Research | Research asia research news
Further information:
http://www.a-star.edu.sg
http://www.researchsea.com

More articles from Materials Sciences:

nachricht Robust and functional – surface finishing by suspension spraying
19.09.2017 | Fraunhofer-Institut für Keramische Technologien und Systeme IKTS

nachricht Graphene and other carbon nanomaterials can replace scarce metals
19.09.2017 | Chalmers University of Technology

All articles from Materials Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Tiny lasers from a gallery of whispers

New technique promises tunable laser devices

Whispering gallery mode (WGM) resonators are used to make tiny micro-lasers, sensors, switches, routers and other devices. These tiny structures rely on a...

Im Focus: Ultrafast snapshots of relaxing electrons in solids

Using ultrafast flashes of laser and x-ray radiation, scientists at the Max Planck Institute of Quantum Optics (Garching, Germany) took snapshots of the briefest electron motion inside a solid material to date. The electron motion lasted only 750 billionths of the billionth of a second before it fainted, setting a new record of human capability to capture ultrafast processes inside solids!

When x-rays shine onto solid materials or large molecules, an electron is pushed away from its original place near the nucleus of the atom, leaving a hole...

Im Focus: Quantum Sensors Decipher Magnetic Ordering in a New Semiconducting Material

For the first time, physicists have successfully imaged spiral magnetic ordering in a multiferroic material. These materials are considered highly promising candidates for future data storage media. The researchers were able to prove their findings using unique quantum sensors that were developed at Basel University and that can analyze electromagnetic fields on the nanometer scale. The results – obtained by scientists from the University of Basel’s Department of Physics, the Swiss Nanoscience Institute, the University of Montpellier and several laboratories from University Paris-Saclay – were recently published in the journal Nature.

Multiferroics are materials that simultaneously react to electric and magnetic fields. These two properties are rarely found together, and their combined...

Im Focus: Fast, convenient & standardized: New lab innovation for automated tissue engineering & drug

MBM ScienceBridge GmbH successfully negotiated a license agreement between University Medical Center Göttingen (UMG) and the biotech company Tissue Systems Holding GmbH about commercial use of a multi-well tissue plate for automated and reliable tissue engineering & drug testing.

MBM ScienceBridge GmbH successfully negotiated a license agreement between University Medical Center Göttingen (UMG) and the biotech company Tissue Systems...

Im Focus: Silencing bacteria

HZI researchers pave the way for new agents that render hospital pathogens mute

Pathogenic bacteria are becoming resistant to common antibiotics to an ever increasing degree. One of the most difficult germs is Pseudomonas aeruginosa, a...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

“Lasers in Composites Symposium” in Aachen – from Science to Application

19.09.2017 | Event News

I-ESA 2018 – Call for Papers

12.09.2017 | Event News

EMBO at Basel Life, a new conference on current and emerging life science research

06.09.2017 | Event News

 
Latest News

Molecular Force Sensors

20.09.2017 | Life Sciences

Producing electricity during flight

20.09.2017 | Power and Electrical Engineering

Tiny lasers from a gallery of whispers

20.09.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>