Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Versatile Capsules

15.04.2014

Multifunctional microcapsules made from metals and tannic acid

Microcapsules with a broad spectrum of applications in biomedicine, catalysis, and technology can be produced by using plant-derived, phenolic tannic acid and a variety of metals. The capsules are formed by a simple self-assembly process, and their properties can be controlled through the choice of metal, as demonstrated by a team of Australian and German researchers in the journal Angewandte Chemie.

Metals and organic molecules can combine to form coordination compounds whose structure and properties depend on the components. Examples from nature include the oxygen-binding heme groups in our red blood cells with their central iron atom or the magnesium complex at the heart of photosynthesis. Scientists have also explored the use of these types of compounds to build things, such as networked scaffold structures.

... more about:
»ARC »MRI »PET »blood »copper »fluorescence »ions »rhodium »structures

A team from the University of Melbourne, the Baker IDI Heart and Diabetes Institute (Melbourne, Australia), and the University Medical Center Freiburg (Germany), is particularly interested in structures in the form of hollow capsules. Led by Frank Caruso, these researchers haven now been able to demonstrate that a single organic ligand, tannic acid, can coordinate to 18 different metals to form capsules made of metal–phenolic networks (MPNs). The metals are aluminum, vanadium, chromium, manganese, iron, cobalt, nickel, copper, zinc, zirconium, molybdenum, ruthenium, rhodium, cadmium, cerium, europium, gadolinium, and terbium.

The production method is simple: just mix tannic acid with a solution of the desired metal ion in the presence of a suitable substrate—in this case microparticles. Removal of the substrate leaves behind hollow microcapsules.

The properties of the capsules depend on the type and number of metal ions. For example, capsules with aluminum have a property profile suitable for drug transport: while they are relatively stable at pH values typical of blood, they come apart at the lower pH values found in some cell compartments. They could thus be used to transport a drug though the blood and release it after entering a cell.

Capsules with europium and terbium ions can be used for multicolored fluorescence labeling of biological samples, as well as for technological applications like flexible color displays. Capsules with manganese are highly promising contrast agents for magnetic resonance imaging (MRI). Capsules with radioactive copper isotopes are good tracers for positron emission tomography (PET). Properties like size, shape, and surface chemistry could be tailored to control the distribution of the capsules in the body. Capsules with radioactive copper and europium could allow for tissue samples to undergo PET followed immediately by fluorescence microscopy.

Catalysis is another possible application. The researchers were able to show that capsules with rhodium catalyze the hydrogenation of quinoline at least as well as conventional rhodium catalysts.

About the Author

Frank Caruso is a professor and Australian Research Council (ARC) Laureate Fellow at The University of Melbourne, Australia. He is also a Director of the ARC Centre of Excellence in Convergent Bio-NanoScience and Technology and is a Fellow of the Australian Academy of Science. His research interests focus on developing advanced nano- and biomaterials.

Author: Frank Caruso, University of Melbourne (Australia), http://www.chemeng.unimelb.edu.au/people/staff.php?person_ID=16579

Title: Engineering Multifunctional Capsules through the Assembly of Metal–Phenolic Networks

Angewandte Chemie International Edition, Permalink to the article: http://dx.doi.org/10.1002/anie.201311136

Frank Caruso | Angewandte Chemie
Further information:
http://pressroom.angewandte.org

Further reports about: ARC MRI PET blood copper fluorescence ions rhodium structures

More articles from Life Sciences:

nachricht Staph ‘Gangs’ Share Nutrients During Infection
21.10.2014 | Vanderbilt University Medical Center

nachricht New Insight That “Mega” Cells Control the Growth of Blood-Producing Cells
21.10.2014 | Stowers Institute for Medical Research

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Anzeige

Anzeige

Event News

Battery Conference April 2015 in Aachen

16.10.2014 | Event News

Experts discuss new developments in the field of stem cell research and cell therapy

10.10.2014 | Event News

Zoonoses: Global collaboration is more important than ever

07.10.2014 | Event News

 
Latest News

Exploring X-Ray phase tomography with synchrotron radiation

21.10.2014 | Medical Engineering

World record in data transmission with smart circuits

21.10.2014 | Information Technology

Scientists restore hearing in noise-deafened mice, pointing way to new therapies

21.10.2014 | Health and Medicine

VideoLinks
B2B-VideoLinks
More VideoLinks >>>