Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

A New Coat for Golden Rods

12.12.2011
Gold isn’t just lovely in jewelry; it has long been used as medicine. Modern medicine is particularly focused on nanoscopic gold, which can be used as a contrast agent and in the treatment of cancer.

In the journal Angewandte Chemie, Eugene R. Zubarev and his team at Rice University in Houston (Texas, USA) have now introduced a new pretreatment process for gold nanorods that could accelerate their use in medical applications.

How can tiny rods of gold help to fight cancer? Cancer cells are more sensitive to temperature than healthy tissue, and this fact can be exploited through local heating of the affected parts of the body. This is where the gold nanorods come into play. They can be introduced into the cancer cells and the diseased areas irradiated with near-infrared light (photoinduced hyperthermia). The rods absorb this light very strongly and transform the light energy into heat, which they transfer to their surroundings.

Gold nanorods are normally produced in a concentrated solution of cetyl trimethylammonium bromide (CTAB) and are thus coated in a double layer of CTAB. The CTAB is only deposited onto the surface, not chemically bound. In an aqueous environment, the CTAB molecules slowly dissolve. This is problematic because CTAB is highly toxic. Simply leaving out the CTAB is no solution because without this coating the nanorods would clump together.

In order to make the rods stable as well as biocompatible, various more or less complex methods of pretreatment have been developed. However, for many of these processes, it is not known how much of the toxic CTAB remains on the nanorods. Another problem is that the pretreatment can disrupt the uptake of the nanorods into cells, which drastically reduces the success of photothermal cancer treatment.

Zubarev and his co-workers have now developed a new strategy that solves these problems: they replaced the CTAB with a variant that contains a sulfur-hydrogen group, abbreviated as MTAB. With various analytical processes, the scientists have been able to prove that the CTAB on these nanorods is completely replaced with an MTAB layer. The MTAB molecules chemically bond to gold nanorods through their sulfur atoms. They bind so tightly that the layer stays in place even in an aqueous solution and the rods can even be freeze-dried. They can be stored indefinitely as a brown powder and dissolve in water again within seconds.

Tests on cell cultures demonstrate that MTAB gold nanorods are not toxic, even at higher concentrations. In addition, they are absorbed in large amounts by tumor cells. The scientists estimate that under the conditions of their experiment, a single cell takes up more than two million nanorods. This would make effective photothermal tumor treatment possible.
About the Author
Dr Eugene Zubarev is an Associate Professor of Chemistry at Rice University, and has been working in the area of nanochemistry and nanomaterials for over 15 years. He is the recipient of the National Science Foundation Career Award and Alfred P. Sloan Research Fellowship.
Author: Eugene R. Zubarev, Rice University, Houston (USA), http://www.owlnet.rice.edu/~zubarev/group.htm
Title: Quantitative Replacement of Cetyl Trimethylammonium Bromide by Cationic Thiol Ligands on the Surface of Gold Nanorods and Their Extremely Large Uptake by Cancer Cells

Angewandte Chemie International Edition, Permalink to the article: http://dx.doi.org/10.1002/anie.201107304

Eugene R. Zubarev | Angewandte Chemie
Further information:
http://pressroom.angewandte.org

More articles from Life Sciences:

nachricht Rainbow colors reveal cell history: Uncovering β-cell heterogeneity
22.09.2017 | DFG-Forschungszentrum für Regenerative Therapien TU Dresden

nachricht The pyrenoid is a carbon-fixing liquid droplet
22.09.2017 | Max-Planck-Institut für Biochemie

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: The pyrenoid is a carbon-fixing liquid droplet

Plants and algae use the enzyme Rubisco to fix carbon dioxide, removing it from the atmosphere and converting it into biomass. Algae have figured out a way to increase the efficiency of carbon fixation. They gather most of their Rubisco into a ball-shaped microcompartment called the pyrenoid, which they flood with a high local concentration of carbon dioxide. A team of scientists at Princeton University, the Carnegie Institution for Science, Stanford University and the Max Plank Institute of Biochemistry have unravelled the mysteries of how the pyrenoid is assembled. These insights can help to engineer crops that remove more carbon dioxide from the atmosphere while producing more food.

A warming planet

Im Focus: Highly precise wiring in the Cerebral Cortex

Our brains house extremely complex neuronal circuits, whose detailed structures are still largely unknown. This is especially true for the so-called cerebral cortex of mammals, where among other things vision, thoughts or spatial orientation are being computed. Here the rules by which nerve cells are connected to each other are only partly understood. A team of scientists around Moritz Helmstaedter at the Frankfiurt Max Planck Institute for Brain Research and Helene Schmidt (Humboldt University in Berlin) have now discovered a surprisingly precise nerve cell connectivity pattern in the part of the cerebral cortex that is responsible for orienting the individual animal or human in space.

The researchers report online in Nature (Schmidt et al., 2017. Axonal synapse sorting in medial entorhinal cortex, DOI: 10.1038/nature24005) that synapses in...

Im Focus: Tiny lasers from a gallery of whispers

New technique promises tunable laser devices

Whispering gallery mode (WGM) resonators are used to make tiny micro-lasers, sensors, switches, routers and other devices. These tiny structures rely on a...

Im Focus: Ultrafast snapshots of relaxing electrons in solids

Using ultrafast flashes of laser and x-ray radiation, scientists at the Max Planck Institute of Quantum Optics (Garching, Germany) took snapshots of the briefest electron motion inside a solid material to date. The electron motion lasted only 750 billionths of the billionth of a second before it fainted, setting a new record of human capability to capture ultrafast processes inside solids!

When x-rays shine onto solid materials or large molecules, an electron is pushed away from its original place near the nucleus of the atom, leaving a hole...

Im Focus: Quantum Sensors Decipher Magnetic Ordering in a New Semiconducting Material

For the first time, physicists have successfully imaged spiral magnetic ordering in a multiferroic material. These materials are considered highly promising candidates for future data storage media. The researchers were able to prove their findings using unique quantum sensors that were developed at Basel University and that can analyze electromagnetic fields on the nanometer scale. The results – obtained by scientists from the University of Basel’s Department of Physics, the Swiss Nanoscience Institute, the University of Montpellier and several laboratories from University Paris-Saclay – were recently published in the journal Nature.

Multiferroics are materials that simultaneously react to electric and magnetic fields. These two properties are rarely found together, and their combined...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

“Lasers in Composites Symposium” in Aachen – from Science to Application

19.09.2017 | Event News

I-ESA 2018 – Call for Papers

12.09.2017 | Event News

EMBO at Basel Life, a new conference on current and emerging life science research

06.09.2017 | Event News

 
Latest News

Rainbow colors reveal cell history: Uncovering β-cell heterogeneity

22.09.2017 | Life Sciences

Penn first in world to treat patient with new radiation technology

22.09.2017 | Medical Engineering

Calculating quietness

22.09.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>