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
Novel mechanisms of action discovered for the skin cancer medication Imiquimod
21.10.2016 | Technische Universität München
Second research flight into zero gravity
21.10.2016 | Universität Zürich
Researchers from the Institute for Quantum Computing (IQC) at the University of Waterloo led the development of a new extensible wiring technique capable of controlling superconducting quantum bits, representing a significant step towards to the realization of a scalable quantum computer.
"The quantum socket is a wiring method that uses three-dimensional wires based on spring-loaded pins to address individual qubits," said Jeremy Béjanin, a PhD...
In a paper in Scientific Reports, a research team at Worcester Polytechnic Institute describes a novel light-activated phenomenon that could become the basis for applications as diverse as microscopic robotic grippers and more efficient solar cells.
A research team at Worcester Polytechnic Institute (WPI) has developed a revolutionary, light-activated semiconductor nanocomposite material that can be used...
By forcefully embedding two silicon atoms in a diamond matrix, Sandia researchers have demonstrated for the first time on a single chip all the components needed to create a quantum bridge to link quantum computers together.
"People have already built small quantum computers," says Sandia researcher Ryan Camacho. "Maybe the first useful one won't be a single giant quantum computer...
COMPAMED has become the leading international marketplace for suppliers of medical manufacturing. The trade fair, which takes place every November and is co-located to MEDICA in Dusseldorf, has been steadily growing over the past years and shows that medical technology remains a rapidly growing market.
In 2016, the joint pavilion by the IVAM Microtechnology Network, the Product Market “High-tech for Medical Devices”, will be located in Hall 8a again and will...
'Ferroelectric' materials can switch between different states of electrical polarization in response to an external electric field. This flexibility means they show promise for many applications, for example in electronic devices and computer memory. Current ferroelectric materials are highly valued for their thermal and chemical stability and rapid electro-mechanical responses, but creating a material that is scalable down to the tiny sizes needed for technologies like silicon-based semiconductors (Si-based CMOS) has proven challenging.
Now, Hiroshi Funakubo and co-workers at the Tokyo Institute of Technology, in collaboration with researchers across Japan, have conducted experiments to...
14.10.2016 | Event News
14.10.2016 | Event News
12.10.2016 | Event News
21.10.2016 | Health and Medicine
21.10.2016 | Information Technology
21.10.2016 | Materials Sciences