Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Contrast Agent for Tumor Diagnostics

24.03.2011
Phosphorescent metal–organic coordination polymers for optical imaging

X-rays are not the only way: visible and especially infrared light can also be used to image human tissue. The effectiveness of optical imaging processes can be significantly improved with suitable dyes used as contrast agents.

In the journal Angewandte Chemie, a team led by Wenbin Lin at the University of North Carolina (Chapel Hill, USA) has now introduced a novel contrast agent that marks tumor cells in vitro. The dye is a phosphorescent ruthenium complex incorporated into nanoparticles of a metal–organic coordination polymer, which allows an extraordinarily high level of dye loading.

Fluorescent dyes accumulate in varying amounts in different types of tissue. Such contrast agents make it possible to use optical imaging to differentiate between healthy and tumorous tissue. However, this method is limited by the fact that very high concentrations of dye are needed to produce sufficiently strong fluorescence. Organic dye molecules packed at high concentrations into nanocapsules tend to quench each other’s fluorescence. Materials that fluoresce more strongly, such as quantum dots, are often not biocompatible.

This team has now developed an alternative: metal complexes connected to form lattice-like coordination polymers. Coordination polymers are metal–organic structures consisting of metal ions, which act as connecting points, linked by bridges made of organic molecules or coordination complexes. The scientists made such polymers with bridges consisting of a light-emitting complex of the metal ruthenium. Zirconium ions proved to be suitable connecting points. These tiny structures form spherical nanoparticles.

The ruthenium complexes do not fluoresce, but rather phosphoresce, which means that they emit light for a proportional length of time after irradiation with light. Because they are not placed inside a nano-transport container, but are a component of the nanoparticle, it is possible to attain a very high level of dye loading—in this instance over 50 %. Quenching of the phosphorescence at high concentrations does not occur in such complexes.

In order to prevent the glowing particles from rapidly dissolving and to increase the biocompatibility, they were coated with thin layers of silicon dioxide and a layer of polyethylene glycol. The latter acts as an anchor point for anisamide, a molecule that specifically binds to receptors that are far more common on the surfaces of many types of tumor cell than on healthy cells.

In a cell culture, it was possible to selectively mark a line of cancer cells with the phosphorescent nanoparticles. The researchers hope that it will be possible to develop contrast agents for the use of optical imaging for tumor detection based on these new metal–organic nanomaterials.

Author: Wenbin Lin, University of North Carolina, Chapel Hill (USA), http://www.chem.unc.edu/people/faculty/linw/wlindex.
Title: Phosphorescent Nanoscale Coordination Polymers as Contrast Agents for Optical Imaging

Angewandte Chemie International Edition, Permalink to the article: http://dx.doi.org/10.1002/anie.201008277

Wenbin Lin | Angewandte Chemie
Further information:
http://pressroom.angewandte.org
http://www.chem.unc.edu/people/faculty/linw/wlindex

More articles from Life Sciences:

nachricht Navigational view of the brain thanks to powerful X-rays
18.10.2017 | Georgia Institute of Technology

nachricht Separating methane and CO2 will become more efficient
18.10.2017 | KU Leuven

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Neutron star merger directly observed for the first time

University of Maryland researchers contribute to historic detection of gravitational waves and light created by event

On August 17, 2017, at 12:41:04 UTC, scientists made the first direct observation of a merger between two neutron stars--the dense, collapsed cores that remain...

Im Focus: Breaking: the first light from two neutron stars merging

Seven new papers describe the first-ever detection of light from a gravitational wave source. The event, caused by two neutron stars colliding and merging together, was dubbed GW170817 because it sent ripples through space-time that reached Earth on 2017 August 17. Around the world, hundreds of excited astronomers mobilized quickly and were able to observe the event using numerous telescopes, providing a wealth of new data.

Previous detections of gravitational waves have all involved the merger of two black holes, a feat that won the 2017 Nobel Prize in Physics earlier this month....

Im Focus: Smart sensors for efficient processes

Material defects in end products can quickly result in failures in many areas of industry, and have a massive impact on the safe use of their products. This is why, in the field of quality assurance, intelligent, nondestructive sensor systems play a key role. They allow testing components and parts in a rapid and cost-efficient manner without destroying the actual product or changing its surface. Experts from the Fraunhofer IZFP in Saarbrücken will be presenting two exhibits at the Blechexpo in Stuttgart from 7–10 November 2017 that allow fast, reliable, and automated characterization of materials and detection of defects (Hall 5, Booth 5306).

When quality testing uses time-consuming destructive test methods, it can result in enormous costs due to damaging or destroying the products. And given that...

Im Focus: Cold molecules on collision course

Using a new cooling technique MPQ scientists succeed at observing collisions in a dense beam of cold and slow dipolar molecules.

How do chemical reactions proceed at extremely low temperatures? The answer requires the investigation of molecular samples that are cold, dense, and slow at...

Im Focus: Shrinking the proton again!

Scientists from the Max Planck Institute of Quantum Optics, using high precision laser spectroscopy of atomic hydrogen, confirm the surprisingly small value of the proton radius determined from muonic hydrogen.

It was one of the breakthroughs of the year 2010: Laser spectroscopy of muonic hydrogen resulted in a value for the proton charge radius that was significantly...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

ASEAN Member States discuss the future role of renewable energy

17.10.2017 | Event News

World Health Summit 2017: International experts set the course for the future of Global Health

10.10.2017 | Event News

Climate Engineering Conference 2017 Opens in Berlin

10.10.2017 | Event News

 
Latest News

Osaka university researchers make the slipperiest surfaces adhesive

18.10.2017 | Materials Sciences

Space radiation won't stop NASA's human exploration

18.10.2017 | Physics and Astronomy

Los Alamos researchers and supercomputers help interpret the latest LIGO findings

18.10.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>