Flares on the move: Nanoparticle test kit shows how nanoparticles of different size disperse in tumor tissue

Jan 11, 2011

(PhysOrg.com) -- Nanoparticles play a significant role in the development of future diagnostic and therapeutic techniques for tumors, for example as transporters for drugs or as contrast agents. Absorption and dispersion of nanoparticles in tumor tissue depend strongly on particle size. In order to systematically study this, scientists at the Massachusetts Institute of Technology and Harvard Medical School have now produced a set of fluorescent nanoparticles of various diameters between 10 and 150 nm. As the team led by Moungi G. Bawendi and Daniel G. Nocera reports in the journal Angewandte Chemie, they were able to use these to simultaneously follow the dispersion of particles of different sizes through mouse tumors in real time.

In order for nanoparticle-based biomedical techniques to work, the nanoparticles must be of optimal size. For studies, it is thus desirable to simultaneously observe the behavior of particles of different size in the same tumor in vivo. This requires chemically comparable particles of various sizes, each size group consisting of particles of uniform size and composition. Additionally, it must be possible to simultaneously detect and differentiate the various particles. Also, they must be biocompatible, and may not form aggregates or adsorb proteins. This complex challenge has now been met.

The researchers developed a set of nanoparticles in various sizes, which can be detected by means of fluorescing . Quantum dots are semiconducting structures at the boundary between macroscopic solid bodies and the quantum-mechanical nano-world. By selectively producing quantum dots of different sizes, it is possible to obtain quantum dots that fluoresce at different defined wavelengths, which allows them to be simultaneously detected and differentiated.

To produce nanoparticles in different size classes, the scientists coated cadmium selenide/ quantum dots with polymer such as and polyethylene glycol. They attained particles larger than 100 nm in diameter by attaching quantum dots to prefabricated silicon dioxide particles and then coating them with polyethylene glycol. For each size class they selected quantum dots that give off light of a different wavelength.

The researchers intravenously injected a mixture of particles with diameters of 12, 60, and 125 nm into mice with cancer. Fluorescence microscopy was used to follow the particles’ entry into the tumor tissue in vivo. Whereas the 12 nm particles easily passed from the blood vessels into the tissue and rapidly spread out, the 60 nm particles passed through the walls of the vein but stayed within 10 µm of the vessel wall, unable to pass farther into the tissue. The 125 nm particles essentially did not pass through the walls of the blood vessels at all.

Explore further: Researchers improve how a peptide can be delivered to the diseased heart tissue of mice via nanotechnology

More information: Moungi G. Bawendi, Daniel G. Nocera, A Nanoparticle Size Series for In Vivo Fluorescence Imaging, Angewandte Chemie International Edition 2010, 49, No. 46, 8649–8652, dx.doi.org/10.1002/anie.201003142

Related Stories

Coated Ultrasmall Quantum Dots Suitable for In Vivo Imaging

Dec 03, 2007

Quantum dots have shown promise in a variety of imaging and therapeutic applications, particularly when they are coated to render them biocompatible. However, such coating can increase the size of quantum dots signficantly, ...

New genre of sugar-coated 'quantum dots' for drug delivery

Mar 04, 2009

(PhysOrg.com) -- Scientists in Switzerland are reporting an advance that could help tap the much-heralded potential of “quantum dots”— nanocrystals that glow when exposed to ultraviolet light — in the treatment of ...

Nanoparticles Provide Detailed View Inside Living Animals

Apr 18, 2008

Using nanoparticles designed specifically to produce a bright Raman spectroscopic signal, a team of investigators at the Center for Cancer Nanotechnology Excellence Focused on Therapy Response (Stanford CCNE) has shown that ...

Tracking tumor-targeting nanoparticles in the body

Oct 27, 2010

Though targeted nanoparticle-based imaging agents and therapeutics for diagnosing and treating cancer are making their way to and through the clinical trials process, researchers still do not have a good understanding of ...

Magnetic nanoparticles: Suitable for cancer therapy?

May 28, 2008

A measuring procedure developed in the Physikalisch-Technische Bundesanstalt (PTB) can help to investigate in some detail the behaviour of magnetic nanoparticles which are used for cancer therapy.

Recommended for you

Nanosafety research: The quest for the gold standard

Oct 29, 2014

Empa toxicologist Harald Krug has lambasted his colleagues in the journal Angewandte Chemie. He evaluated several thousand studies on the risks associated with nanoparticles and discovered no end of shortc ...

New nanodevice to improve cancer treatment monitoring

Oct 27, 2014

In less than a minute, a miniature device developed at the University of Montreal can measure a patient's blood for methotrexate, a commonly used but potentially toxic cancer drug. Just as accurate and ten ...

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.