Quantum Rods and Dots Image Cancer Cells

Feb 26, 2007

Brightly fluorescent quantum dots and quantum rods are quickly becoming important tools for identifying specific molecules and cells in living systems. Two new reports demonstrate some of the ways in which cancer researchers are using these nanoscale imaging agents.

Hideo Higuchi, Ph.D., and colleagues at Tohoku University in Japan, used antibody-labeled quantum dots and a high-sensitivity fluorescence microscope fitted with a video camera to make 30-frame-per-second movies of these nanoparticles as they traveled through the bloodstream to tumors in mice. In a paper published in the journal Cancer Research, the investigators identified six distinct steps in the process by which quantum dots labeled with the HER2 monoclonal antibody travel from the site of injection to the space surrounding the cell nucleus. The HER2 monoclonal antibody binds to a protein found on the surface of certain breast and other tumors.

Using the labeled quantum dots, the researchers obtained quantative measurements of these six steps. From these experiments, the investigators were able to determine that each stage of the delivery process proceeds in a stop-and-go manner. The researchers note that a better understanding of each of these steps could improve the ability of nanoparticles to deliver drugs specifically to tumors.

In another study, Paras Prasad, Ph.D., and his colleagues at the State University of New York in Buffalo showed that they could create water-soluble quantum rods that can be used as targeted probes for imaging cancer cells using a technique known as two-photon fluorescence imaging. Quantum rods, like spherical quantum dots, can be made to fluoresce with a wide range of colors, but the larger dimensions of quantum rods make them easier to excite with incoming light than their spherical cousins. This work, conducted as part of the Multifunctional Nanoparticles in Diagnosis and Therapy of Pancreatic Cancer Platform Partnership, was published in the journal Nano Letters.

Prasad and his collaborators first developed a new method for making quantum rods that would remain well-dispersed in water, and then refined their synthetic technique to also include the ability to attach targeting molecules to the surface of the quantum rods. In the reported experiments, the investigators attached a protein known as transferrin to the quantum rods. Transferrin binds to a receptor that is overexpressed on many types of cancer cells.

Experiments with these labeled quantum rods showed that they were only taken up by targeted cells, and that they accumulated within the targeted cells. The quantum rods were readily visible within the cells using low-intensity near-infrared light. The ability to use low-intensity light to detect the quantum rods helps protect the integrity of the targeted cells.

The work with quantum dots is detailed in a paper titled, “In vivo real-time tracking of single quantum dots conjugated with monoclonal anti-HER2 antibody in tumors of mice.” An abstract of this paper is available through PubMed.

The work with quantum rods, which was supported by the National Cancer Institute’s Alliance for Nanotechnology in Cancer, is detailed in a paper titled, “Quantum rod bioconjugates as targeted probes for confocal and two-photon fluorescence imaging of cancer cells.” This paper was published online in advance of print publication. An abstract of this paper is available through PubMed.

Source: National Cancer Institute

Explore further: A new way to make microstructured surfaces

add to favorites email to friend print save as pdf

Related Stories

A sweet defense against lethal bacteria

May 31, 2011

(PhysOrg.com) -- There is now a promising vaccine candidate for combating the pathogen which causes one of the most common and dangerous hospital infections. An international team of scientists from the Max ...

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 ...

'Strained' quantum dots show new optical properties

Dec 07, 2008

Quantum dots, tiny luminescent particles made of semiconductors, hold promise for detecting and treating cancer earlier. However, if doctors were to use them in humans, quantum dots could have limitations related to their ...

Nanosize Rods Light Up Pancreatic Cancer Cells

Apr 18, 2008

Quantum dots have shown promise as ultrabright contrast agents for use in a variety of cancer imaging studies. Now, a team of investigators at the Multifunctional Nanoparticles in Diagnosis and Therapy of Pancreatic Cancer ...

Recommended for you

A new way to make microstructured surfaces

3 minutes ago

A team of researchers has created a new way of manufacturing microstructured surfaces that have novel three-dimensional textures. These surfaces, made by self-assembly of carbon nanotubes, could exhibit a ...

Tough foam from tiny sheets

19 hours ago

Tough, ultralight foam of atom-thick sheets can be made to any size and shape through a chemical process invented at Rice University.

Graphene surfaces on photonic racetracks

Jul 28, 2014

In an article published in Optics Express, scientists from The University of Manchester describe how graphene can be wrapped around a silicon wire, or waveguide, and modify the transmission of light through it.

Simulating the invisible

Jul 28, 2014

Panagiotis Grammatikopoulos in the OIST Nanoparticles by Design Unit simulates the interactions of particles that are too small to see, and too complicated to visualize. In order to study the particles' behavior, he uses ...

User comments : 0