Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Targeted nanospheres find, penetrate, then fuel burning of melanoma

04.02.2009
Peptide-guided hollow gold spheres gather inside tumors, where light heats them to kill

Hollow gold nanospheres equipped with a targeting peptide find melanoma cells, penetrate them deeply, and then cook the tumor when bathed with near-infrared light, a research team led by scientists at The University of Texas M. D. Anderson Cancer Center reported in the Feb. 1 issue of Clinical Cancer Research.

"Active targeting of nanoparticles to tumors is the holy grail of therapeutic nanotechnology for cancer. We're getting closer to that goal," said senior author Chun Li, Ph.D., professor in M. D. Anderson's Department of Experimental Diagnostic Imaging. When heated with lasers, the actively targeted hollow gold nanospheres did eight times more damage to melanoma tumors in mice than did the same nanospheres that gathered less directly in the tumors.

Lab and mouse model experiments demonstrated the first in vivo active targeting of gold nanostructures to tumors in conjunction with photothermal ablation - a minimally invasive treatment that uses heat generated through absorption of light to destroy target tissue. Tumors are burned with near-infrared light, which penetrates deeper into tissue than visible or ultraviolet light.

Photothermal ablation is used to treat some cancers by embedding optical fibers inside tumors to deliver near-infrared light. Its efficiency can be greatly improved when a light-absorbing material is applied to the tumor, Li said. Photothermal ablation has been explored for melanoma, but because it also hits healthy tissue, dose duration and volume have been limited.

Lower light dose, great damage

With hollow gold nanospheres inside melanoma cells, photothermal ablation destroyed tumors in mice with a laser light dose that was 12 percent of the dose required when the nanospheres aren't applied, Li and colleagues report. Such a low dose is more likely to spare surrounding tissue.

Injected, untargeted nanoparticles accumulate in tumors because they are so small that they fit through the larger pores of abnormal blood vessels that nourish cancer, Li said. This "passive targeting" delivers a low dose of nanoparticles and concentrates them near the cell's vasculature.

The researchers packaged hollow, spherical gold nanospheres with a peptide - a small compound composed of amino acids - that binds to the melanocortin type 1 receptor, which is overly abundant in melanoma cells. They first treated melanoma cells in culture and later injected both targeted and untargeted nanospheres into mice with melanoma, then applied near-infrared light.

Fluorescent tagging of the targeted nanospheres showed that they were embedded in cultured melanoma cells, while hollow gold nanospheres without the targeting peptide were not. The targeted nanospheres were actively drawn into the cells through the cell membrane.

When the researchers beamed near-infrared light onto treated cultures, most cells with targeted nanospheres died, and almost all of those left were irreparably damaged. Only a small fraction of cells treated with untargeted nanospheres died. Cells treated only with near-infrared light or only with the nanospheres were undamaged.

An 8-fold increase in tumor destruction

In the mouse model, fluorescent tagging showed that the plain hollow gold nanospheres only accumulated near the tumor's blood vessels, while the targeted nanospheres were found throughout the tumor.

"There are many biological barriers to effective use of nanoparticles, with the liver and spleen being the most important," Li said. The body directs foreign particles and defective cells to those organs for destruction.

Most of the targeted nanospheres in the treated mice gathered in the tumor, with smaller amounts found in the liver and spleen. Most of the untargeted nanospheres gathered in the spleen, then in the liver and then the tumor, demonstrating the selectivity and importance of targeting.

In another group of mice, near-infrared light beamed into tumors with targeted nanospheres destroyed 66 percent of the tumors, but only destroyed 7.9 percent of tumors treated with untargeted nanospheres.

The researchers used F-18-labeled glucose to monitor tumor activity by observing how much glucose it metabolized. This action "lights up" the tumor for positron emission tomography (PET) imaging. Tumors treated with targeted shells largely went dark.

"Clinical implications of this approach are not limited to melanoma," Li said. "It's also a proof of principle that receptors common to other cancers can also be targeted by a peptide-guided hollow gold nanosphere. We've also shown that non-invasive PET can monitor early response to treatment."

The targeted nanospheres have a number of advantages, said Jin Zhang, Ph.D., professor in the University of California-Santa Cruz Department of Chemistry and developer of the hollow nanospheres. Their size - small even for nanoparticles at 40-50 nanometers in diameter - and spherical shape allow for greater uptake and cellular penetration. They have strong, but narrow and tunable ability to absorb light across the visible and near-infrared spectrum, making them unique from other metal nanoparticles.

The hollow spheres are pure gold, which has a long history of safe medical use with few side-effects, Li said.

Scott Merville | EurekAlert!
Further information:
http://www.mdanderson.org

More articles from Health and Medicine:

nachricht Team discovers how bacteria exploit a chink in the body's armor
20.01.2017 | University of Illinois at Urbana-Champaign

nachricht Rabies viruses reveal wiring in transparent brains
19.01.2017 | Rheinische Friedrich-Wilhelms-Universität Bonn

All articles from Health and Medicine >>>

The most recent press releases about innovation >>>

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

Im Focus: Traffic jam in empty space

New success for Konstanz physicists in studying the quantum vacuum

An important step towards a completely new experimental access to quantum physics has been made at University of Konstanz. The team of scientists headed by...

Im Focus: How gut bacteria can make us ill

HZI researchers decipher infection mechanisms of Yersinia and immune responses of the host

Yersiniae cause severe intestinal infections. Studies using Yersinia pseudotuberculosis as a model organism aim to elucidate the infection mechanisms of these...

Im Focus: Interfacial Superconductivity: Magnetic and superconducting order revealed simultaneously

Researchers from the University of Hamburg in Germany, in collaboration with colleagues from the University of Aarhus in Denmark, have synthesized a new superconducting material by growing a few layers of an antiferromagnetic transition-metal chalcogenide on a bismuth-based topological insulator, both being non-superconducting materials.

While superconductivity and magnetism are generally believed to be mutually exclusive, surprisingly, in this new material, superconducting correlations...

Im Focus: Studying fundamental particles in materials

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...

Im Focus: Designing Architecture with Solar Building Envelopes

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...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Sustainable Water use in Agriculture in Eastern Europe and Central Asia

19.01.2017 | Event News

12V, 48V, high-voltage – trends in E/E automotive architecture

10.01.2017 | Event News

2nd Conference on Non-Textual Information on 10 and 11 May 2017 in Hannover

09.01.2017 | Event News

 
Latest News

Helmholtz International Fellow Award for Sarah Amalia Teichmann

20.01.2017 | Awards Funding

An innovative high-performance material: biofibers made from green lacewing silk

20.01.2017 | Materials Sciences

Ion treatments for cardiac arrhythmia — Non-invasive alternative to catheter-based surgery

20.01.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>