Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Newly designed nanoparticle quantum dots simultaneously target and image prostate tumors in mice

28.07.2004


Emory University scientists have for the first time used a new class of luminescent "quantum dot" nanoparticles in living animals to simultaneously target and image cancerous tumors. The quantum dots were encapsulated in a highly protective polymer coating and attached to a monoclonal antibody that guided them to prostate tumor sites in living mice, where they were visible using a simple mercury lamp. The scientists believe the ability to both target and image cells in vivo represents a significant step in the quest to eventually use nanotechnology to target, image, and treat cancer, cardiovascular plaques, and neurodegenerative disease in humans. The findings were published on-line July 18 in the journal Nature Biotechnology and will appear in the journal’s August 1 print edition.



The research team was led by Shuming Nie, PhD, a nanotechnology expert and a professor in the Coulter Department of Biomedical Engineering at Emory and the Georgia Institute of Technology and in Emory’s Winship Cancer Institute, and by Lelund Chung, PhD, professor of urology in Emory University School of Medicine and the Winship Cancer Institute. Quantum dots are nanometer-sized luminescent semiconductor crystals that have unique chemical and physical properties due to their size and their highly compact structure. Quantum dots can be chemically linked (conjugated) to molecules such as antibodies, peptides, proteins or DNA and engineered to detect other molecules, such as those present on the surface of cancer cells.

The researchers injected human prostate cancer cells under the skin of mice to promote growth of solid prostate tumors. They then encapsulated quantum dots, made from cadmium selenide, within a highly protective coating called an ABC triblock copolymer, and over-coated the particle-polymer composite with poly (ethylene glycol). They injected the quantum dots into the circulatory system of the mice first to test "passive" targeting of the tumor. Tumors grow extra blood vessels in a process called angiogenesis. These angiogenic vessels are very porous, which allowed the quantum dots to leak out and accumulate at the tumor sites, where they could be detected by fluorescence imaging.


The scientists then conjugated the quantum dots to a highly specific monoclonal antibody targeted to a prostate-specific membrane antigen (PMSA) on the cell surface of the prostate tumor cells. When they injected the conjugated quantum dots into the circulatory system of the mice, the dots selectively accumulated at the site of the tumor through binding to the antigen target. The new triblock polymer coating protected the quantum dots from attack by enzymes and other biomolecules. The active method of tumor targeting using the monoclonal antibody was much faster and more efficient than was the passive method without the antibody.

"Although other research groups have used quantum dots to either target or image cells, we believe this is the first time in vivo targeting and imaging has been achieved simultaneously," said Xiaohu Gao, PhD a postdoctoral fellow in Dr. Nie’s group.

In previous studies without using the ABC triblock polymer, Emory scientists and other researchers experienced a significant loss of fluorescence in quantum dots that were administered to live animals. "This polymer appears to lend a great deal of protection and stability to the quantum dot probes inside the animals," Dr. Gao said. "Also, cadmium and selenium ions are highly toxic, and this polymer acts like a plastic bag to protect the quantum dots from degradation and leakage."

"This is a new class of quantum dot conjugates designed specifically for complex in vivo applications," said Dr. Nie. "They are stable over a broad range of pH and salt conditions and maintain their stability even after treatment with hydrochloric acid."

Quantum dots are more brightly fluorescent than traditional dyes and fluorescent proteins often used for imaging, and because they emit different wavelengths over a broad range of the light spectrum from visible to infrared, depending on their size and chemical composition, it is possible to "tune" them to tag and detect multiple biomarkers simultaneously. They can be illuminated by a light source, such as a laser or mercury lamp. Different sized quantum dots can be combined to detect multiple targets in a process called "multiplexing." And quantum dots are more resistant to photobleaching or fading than are conventional dyes used in imaging.

"It has been a difficult task to achieve both targeting and imaging in living animal models," Dr. Nie said. "The larger surface area provided by quantum dots should allow the conjugation of multiple agents, and we envision the development of diagnostic and therapeutic dual-modality quantum dots."

"We believe the unique properties of quantum dots will eventually allow us to use multiple colors and intensities to monitor multiple parameters at the same time for precise diagnosis and targeted treatment," Dr. Gao said. "We are developing quantum dots in the near-infrared spectrum, which should improve our ability for non-invasive and more sensitive imaging of deeper tissues."

Holly Korschun | EurekAlert!
Further information:
http://www.emory.edu

More articles from Life Sciences:

nachricht A Map of the Cell’s Power Station
18.08.2017 | Albert-Ludwigs-Universität Freiburg im Breisgau

nachricht On the way to developing a new active ingredient against chronic infections
18.08.2017 | Deutsches Zentrum für Infektionsforschung

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Fizzy soda water could be key to clean manufacture of flat wonder material: Graphene

Whether you call it effervescent, fizzy, or sparkling, carbonated water is making a comeback as a beverage. Aside from quenching thirst, researchers at the University of Illinois at Urbana-Champaign have discovered a new use for these "bubbly" concoctions that will have major impact on the manufacturer of the world's thinnest, flattest, and one most useful materials -- graphene.

As graphene's popularity grows as an advanced "wonder" material, the speed and quality at which it can be manufactured will be paramount. With that in mind,...

Im Focus: Exotic quantum states made from light: Physicists create optical “wells” for a super-photon

Physicists at the University of Bonn have managed to create optical hollows and more complex patterns into which the light of a Bose-Einstein condensate flows. The creation of such highly low-loss structures for light is a prerequisite for complex light circuits, such as for quantum information processing for a new generation of computers. The researchers are now presenting their results in the journal Nature Photonics.

Light particles (photons) occur as tiny, indivisible portions. Many thousands of these light portions can be merged to form a single super-photon if they are...

Im Focus: Circular RNA linked to brain function

For the first time, scientists have shown that circular RNA is linked to brain function. When a RNA molecule called Cdr1as was deleted from the genome of mice, the animals had problems filtering out unnecessary information – like patients suffering from neuropsychiatric disorders.

While hundreds of circular RNAs (circRNAs) are abundant in mammalian brains, one big question has remained unanswered: What are they actually good for? In the...

Im Focus: RAVAN CubeSat measures Earth's outgoing energy

An experimental small satellite has successfully collected and delivered data on a key measurement for predicting changes in Earth's climate.

The Radiometer Assessment using Vertically Aligned Nanotubes (RAVAN) CubeSat was launched into low-Earth orbit on Nov. 11, 2016, in order to test new...

Im Focus: Scientists shine new light on the “other high temperature superconductor”

A study led by scientists of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg presents evidence of the coexistence of superconductivity and “charge-density-waves” in compounds of the poorly-studied family of bismuthates. This observation opens up new perspectives for a deeper understanding of the phenomenon of high-temperature superconductivity, a topic which is at the core of condensed matter research since more than 30 years. The paper by Nicoletti et al has been published in the PNAS.

Since the beginning of the 20th century, superconductivity had been observed in some metals at temperatures only a few degrees above the absolute zero (minus...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Call for Papers – ICNFT 2018, 5th International Conference on New Forming Technology

16.08.2017 | Event News

Sustainability is the business model of tomorrow

04.08.2017 | Event News

Clash of Realities 2017: Registration now open. International Conference at TH Köln

26.07.2017 | Event News

 
Latest News

A Map of the Cell’s Power Station

18.08.2017 | Life Sciences

Engineering team images tiny quasicrystals as they form

18.08.2017 | Physics and Astronomy

Researchers printed graphene-like materials with inkjet

18.08.2017 | Materials Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>