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.
Angewandte Chemie International Edition, Permalink to the article: http://dx.doi.org/10.1002/anie.201008277
Wenbin Lin | Angewandte Chemie
Nanoparticle Exposure Can Awaken Dormant Viruses in the Lungs
16.01.2017 | Helmholtz Zentrum München - Deutsches Forschungszentrum für Gesundheit und Umwelt
Cholera bacteria infect more effectively with a simple twist of shape
13.01.2017 | Princeton University
Laser-driving of semimetals allows creating novel quasiparticle states within condensed matter systems and switching between different states on ultrafast time scales
Studying properties of fundamental particles in condensed matter systems is a promising approach to quantum field theory. Quasiparticles offer the opportunity...
Among the general public, solar thermal energy is currently associated with dark blue, rectangular collectors on building roofs. Technologies are needed for aesthetically high quality architecture which offer the architect more room for manoeuvre when it comes to low- and plus-energy buildings. With the “ArKol” project, researchers at Fraunhofer ISE together with partners are currently developing two façade collectors for solar thermal energy generation, which permit a high degree of design flexibility: a strip collector for opaque façade sections and a solar thermal blind for transparent sections. The current state of the two developments will be presented at the BAU 2017 trade fair.
As part of the “ArKol – development of architecturally highly integrated façade collectors with heat pipes” project, Fraunhofer ISE together with its partners...
At TU Wien, an alternative for resource intensive formwork for the construction of concrete domes was developed. It is now used in a test dome for the Austrian Federal Railways Infrastructure (ÖBB Infrastruktur).
Concrete shells are efficient structures, but not very resource efficient. The formwork for the construction of concrete domes alone requires a high amount of...
Many pathogens use certain sugar compounds from their host to help conceal themselves against the immune system. Scientists at the University of Bonn have now, in cooperation with researchers at the University of York in the United Kingdom, analyzed the dynamics of a bacterial molecule that is involved in this process. They demonstrate that the protein grabs onto the sugar molecule with a Pac Man-like chewing motion and holds it until it can be used. Their results could help design therapeutics that could make the protein poorer at grabbing and holding and hence compromise the pathogen in the host. The study has now been published in “Biophysical Journal”.
The cells of the mouth, nose and intestinal mucosa produce large quantities of a chemical called sialic acid. Many bacteria possess a special transport system...
UMD, NOAA collaboration demonstrates suitability of in-orbit datasets for weather satellite calibration
"Traffic and weather, together on the hour!" blasts your local radio station, while your smartphone knows the weather halfway across the world. A network of...
10.01.2017 | Event News
09.01.2017 | Event News
05.01.2017 | Event News
16.01.2017 | Power and Electrical Engineering
16.01.2017 | Information Technology
16.01.2017 | Power and Electrical Engineering