Solid gold nanoparticles have long been used to treat rheumatoid arthritis and more recently have shown promise in treating various types of cancer. Now, thanks to work by Shuming Nie, Ph.D., and his colleagues at the Emory-Georgia Tech Nanotechnology Center for Personalized and Predictive Oncology, these same nanoparticles could serve as a powerful tumor-homing beacon for detecting microscopic tumors or even individual malignant cells. The researchers report their findings in the journal Nature Biotechnology.
Starting with colloidal gold—a commercially available suspension of gold nanoparticles—the investigators attached one of several positively charged organic dye molecules to the particles’ surfaces. The chosen dye molecules absorb and emit light in the near-infrared region of the spectrum, a portion of the spectrum that passes unabsorbed through biological tissues.
The researchers then added a nanometer-thick layer of polyethylene glycol (PEG) to render the construct biocompatible. To their surprise, this coating also made the resulting optical probe incredibly stable under even harsh chemical conditions. More importantly, the optical properties of both the gold nanoparticles and the dye molecules remained constant even after application of the coating. These particles were also nontoxic to cells over periods as long as 6 days.
These initial experiments showed that the coated gold nanoparticles could serve as potent imaging agents for studies of cancer cells, but the real goal of this project was to develop targeted in vivo imaging agents for detecting cancer in humans.
To prepare a targeted nanoparticle, the researchers used a version of PEG to which they could chemically link an antibody that binds to epidermal growth factor receptor (EGFR), a molecule overexpressed on many types of tumors. Antibodies and small molecules that bind to EGFR have been approved to treat non-small cell lung cancer.
The investigators injected the targeted nanoparticles into mice with EGFR-positive human head and neck carcinomas and obtained SERS spectra 5 hours later. As control experiments, the researchers injected matching mice with the untargeted nanoparticle. The unique optical spectra of the nanoparticles were easily detected in both sets of animals, but only the targeted nanoparticles accumulated in tumors. In contrast, the untargeted nanoparticles accumulated largely in the liver.
This work, which was supported by the National Cancer Institute’s (NCI) Alliance for Nanotechnology in Cancer, is detailed in the paper “In vivo tumor targeting and spectroscopic detection with surface-enhanced Raman nanoparticle tags.” An abstract of this paper is available
through PubMed.
Source: National Cancer Institute
Related stories:
MU scientists go green with gold, distribute environmentally friendly nanoparticles
Gold nanoparticles are everywhere. They are used in cancer treatments, automobile sensors, cell phones, blood sugar monitors and hydrogen gas production. However, until recently, scientists couldn't create the nanoparticles without producing synthetic chemicals that had negative impacts on the environment. A new method, created by a University of Missouri research team, not only eliminates any negative environmental impact, but also has resulted in national and international recognition for the lead scientist. The research was published recently in the journal
Small.
New technique sees into tissue at greater depth, resolution
By coupling a kicked-up version of microscopy with miniscule particles of gold, Duke University scientists are now able to peer so deep into living tissue that they can see molecules interacting.
Golden Nanorods for Medical Applications
(PhysOrg.com) -- Gold nanoparticles are under consideration for a number of biomedical applications, such as tumor treatment. A German-American research team at Carnegie Mellon University in Pittsburgh, Hunter College in New York, and the RWTH Aachen has now developed a new method for the production of nanoscopic gold rods. In contrast to previous methods, they have achieved this without the use of cytotoxic additives. As they report in the journal
Angewandte Chemie, the synthesis is not carried out in water, but in an ionic liquid, a “liquid salt”.
Engineering new uses for gold
The glitter of gold may hold more than just beauty, or so says a team of MIT researchers that is working on ways to use tiny gold rods to fight cancer, deliver drugs and more.
Nanoparticles Detect Telomerase Activity
Telomerase, an enzyme that prevents chromosomes from shortening when they divide, is widely suspected of playing a key role in making cancer cells immortal. Though researchers have developed a variety of methods for measuring the activity of this enzyme, none of these methods have proved suitable for use in diagnostic assays for cancer or in efforts to develop drugs that block telomerase activity.
Cancer drug delivery research cuts time from days to hours
Researchers at Case Western Reserve University have developed a technique that has the potential to deliver cancer-fighting drugs to diseased areas within hours, as opposed to the two days it currently takes for existing delivery systems.
Using magnetic nanoparticles to combat cancer
Scientists at Georgia Tech have developed a potential new treatment against cancer that attaches magnetic nanoparticles to cancer cells, allowing them to be captured and carried out of the body. The treatment, which has been tested in the laboratory and will now be looked at in survival studies, is detailed online in the
Journal of the American Chemical Society.
Laser surgery probe targets individual cancer cells
Mechanical engineering Assistant Professor Adela Ben-Yakar at The University of Texas at Austin has developed a laser "microscalpel" that destroys a single cell while leaving nearby cells intact, which could improve the precision of surgeries for cancer, epilepsy and other diseases.