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
Make way for the mini flying machines
21.03.2018 | American Chemical Society
New 4-D printer could reshape the world we live in
21.03.2018 | American Chemical Society
In just a few weeks from now, the Chinese space station Tiangong-1 will re-enter the Earth's atmosphere where it will to a large extent burn up. It is possible that some debris will reach the Earth's surface. Tiangong-1 is orbiting the Earth uncontrolled at a speed of approx. 29,000 km/h.Currently the prognosis relating to the time of impact currently lies within a window of several days. The scientists at Fraunhofer FHR have already been monitoring Tiangong-1 for a number of weeks with their TIRA system, one of the most powerful space observation radars in the world, with a view to supporting the German Space Situational Awareness Center and the ESA with their re-entry forecasts.
Following the loss of radio contact with Tiangong-1 in 2016 and due to the low orbital height, it is now inevitable that the Chinese space station will...
Fraunhofer Institute for Organic Electronics, Electron Beam and Plasma Technology FEP, provider of research and development services for OLED lighting solutions, announces the founding of the “OLED Licht Forum” and presents latest OLED design and lighting solutions during light+building, from March 18th – 23rd, 2018 in Frankfurt a.M./Germany, at booth no. F91 in Hall 4.0.
They are united in their passion for OLED (organic light emitting diodes) lighting with all of its unique facets and application possibilities. Thus experts in...
A new scenario seeking to explain how Mars' putative oceans came and went over the last 4 billion years implies that the oceans formed several hundred million...
For the first time, an interdisciplinary team from the University of Basel has succeeded in integrating artificial organelles into the cells of live zebrafish embryos. This innovative approach using artificial organelles as cellular implants offers new potential in treating a range of diseases, as the authors report in an article published in Nature Communications.
In the cells of higher organisms, organelles such as the nucleus or mitochondria perform a range of complex functions necessary for life. In the networks of...
Animal photoreceptors capture light with photopigments. Researchers from the University of Göttingen have now discovered that these photopigments fulfill an...
19.03.2018 | Event News
16.03.2018 | Event News
13.03.2018 | Event News
21.03.2018 | Physics and Astronomy
21.03.2018 | Materials Sciences
21.03.2018 | Life Sciences