Multifunctional nanoparticle platforms for targeting and imaging cancer cells

Jun 22, 2007

There has been much recent interest in how nanotechnology will impact the field of medicine. Unfortunately, a number of promising nanostructured systems have turned out to be extremely toxic to humans, thus precluding their use in clinical applications and dashing hopes of an early success for the interdisciplinary field of nanobiotechnology.

Now a group of researchers at the University of Michigan Nanotechnology Institute for Medicine and Biological Sciences have devised a multifunctional nanoparticle platform comprising nanoparticles synthesized within dendrimers equipped with targeting molecules and dyes. These dendrimer nanoparticle systems are able to seek out and specifically bind to cancer cells.

Xiangyang Shi, Suhe Wang, James R. Baker Jr., and their colleagues have designed dendrimer nanoparticle systems that are stable, water soluble, and biocompatible. The researchers start out by synthesizing gold nanoparticles within amine-terminated dendrimers. Next, dye molecules and a targeting molecule, folic acid, are attached to the ends of the dendrimers.

Finally, the remaining amine groups are acetylated to ensure that the complex particles do not bear any surface charges. This last step is especially important to ensure the biocompatibility of these systems and to prevent the nonspecific adhesion of other materials. Molecular dynamics simulations indicate that the folic acid attachments project out into the solvent and are readily available for binding to cells, whereas the dye molecules stay far removed from the metal nanoparticles and thus retain their bright fluorescence.

Many cancer cells, including those implicated in cancers of the ovary, kidney, uterus, testis, brain, colon, and lungs, tend to overexpress folic acid receptors. Owing to the folic acid attachments grafted onto the dendrimer nanoparticles, the dendrimer nanoparticles are seen to latch onto the cancer cells via these folic acid receptors. Since the dendrimer nanoparticles are also equipped with dye molecules, the high concentrations of nanoparticles accumulated in the cancer cells can be imaged by confocal microscopy, and indeed diseased cells can be easily told apart from healthy cells.

Further verification comes from electron microscopy experiments. The high contrast provided by the gold nanoparticles allows the determination of the specific sites in the cell machinery where the nanoparticles are attached. Shi pointed out that it should be possible to design dendrimer nanoparticles with other biological ligands such as proteins and antibodies to image and target various biological systems.

“Beyond imaging, it may also be possible to specifically target and destroy cancer cells that internalize the nanoparticles by applying laser heat that intensifies in the presence of gold nanoparticles”, said Wang. “Another possibility is the attachment of drug molecules to these dendrimer nanoparticle systems”, added Baker, “since this will allow the direct delivery of drugs to the target cells”. The researchers are currently conducting further in vivo experiments to evaluate the suitability of this system for clinical applications.

Citation: Xiangyang Shi, Dendrimer-Entrapped Gold Nanoparticles as a Platform, Small 2007, 3, No. 7, 1245–1252, doi: 10.1002/smll.200700054

Source: John Wiley & Sons

Explore further: Scientists trace nanoparticles from plants to caterpillars

add to favorites email to friend print save as pdf

Related Stories

Nanoparticles help researchers deliver steroids to retina

Dec 13, 2011

Hitching a ride into the retina on nanoparticles called dendrimers offers a new way to treat age-related macular degeneration and retinitis pigmentosa. A collaborative research study among investigators at Wayne State University, ...

Polymeric nanoparticles attack head and neck cancer

Jul 15, 2011

Head and neck cancer, the sixth most common cancer in the world, has remained one of the more difficult malignancies to treat, and even when treatment is successful, patients suffer severely from the available therapies. ...

Recommended for you

Gold nanorods target cancer cells

6 hours ago

Using tiny gold nanorods, researchers at Swinburne University of Technology have demonstrated a potential breakthrough in cancer therapy.

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.