Watery Nanoparticles Deliver Anticancer Therapy

Mar 07, 2007

Ultrafine nanoparticles made of a lacy web of polymer and tiny pockets of water may prove to be an ideal vehicle for delivering light-activated drugs to tumors. Preliminary experiments, published in the journal Angewandte Chemie International Edition, show that cancer cells die quickly when treated with these nanoparticles and exposed to light.

Raoul Kopelman, Ph.D., and colleagues from the University of Michigan developed a versatile chemical technique for creating ultrafine nanosized hydrogels, essentially a network of polymer chains that absorb as much as 99 percent of their weight in water.

The researchers used the well-studied polymer known as polyacrylamide as the foundation for creating 2-nanometer-diameter nanoparticles that have no charge on their surfaces. This lack of charge prevents blood proteins from sticking to the surface of the nanoparticles. Combined with the fact that these nanoparticles are too small to be recognized by the immune system, the result is a nanoscale drug delivery vehicle with the ability to remain in circulation long enough to reach and permeate tumors before being excreted through the kidneys.

The investigators’ first test of these new nanoscale hydrogels was to use them as a drug delivery vehicle for a water-insoluble light-activated drug known as a photosensitizer. In particular, the researchers chose a compound known as meta-tetra(hydroxyphenyl) chlorin, or mTHPC, which was recently approved by European regulators for use in treating head and neck cancer. mTHPC produces cell-killing reactive oxygen when irradiated with red light, but not without serious side effects resulting from the method now used to deliver this drug to tumors.

When added to the chemical mixture used to create the nanoparticles, mTHPC becomes trapped within the polymer framework. Characterization experiments showed that this photosensitizer does not escape from the nanoparticles, yet is still capable of producing the same amount of reactive oxygen as if it were free in solution. When added to human brain cancer cells growing in culture and irradiated with red light, this formulation kills the cells rapidly. Empty nanoparticles had no effect on the cells. Neither did drug-loaded nanoparticles added to the cells that were kept in the dark.

This work, which was supported by the National Cancer Institute’s Unconventional Innovations Program, is detailed in a paper titled, “Ultrafine hydrogel nanoparticles: synthetic approach and therapeutic application in living cells.” An abstract of this paper is available through PubMed.

Source: National Cancer Institute

Explore further: Nanoparticles release drugs to reduce tooth decay

Related Stories

Nano packages for anti-cancer drug delivery

Mar 18, 2015

Cancer stem cells are resistant to chemotherapy and consequently tend to remain in the body even after a course of treatment has finished, where they can often trigger cancer recurrence or metastasis. A new ...

New nanodevice defeats drug resistance

Mar 02, 2015

Chemotherapy often shrinks tumors at first, but as cancer cells become resistant to drug treatment, tumors can grow back. A new nanodevice developed by MIT researchers can help overcome that by first blocking ...

How green tea could help improve MRIs

Mar 18, 2015

Green tea's popularity has grown quickly in recent years. Its fans can drink it, enjoy its flavor in their ice cream and slather it on their skin with lotions infused with it. Now, the tea could have a new, ...

Innovative light therapy reaches deep tumors

Mar 09, 2015

Light long has been used to treat cancer. But phototherapy is only effective where light easily can reach, limiting its use to cancers of the skin and in areas accessible with an endoscope, such as the gastrointestinal ...

Recommended for you

Nanoparticles release drugs to reduce tooth decay

6 hours ago

Therapeutic agents intended to reduce dental plaque and prevent tooth decay are often removed by saliva and the act of swallowing before they can take effect. But a team of researchers has developed a way ...

Combining magnetism and light to fight cancer

10 hours ago

By combining, in a liposome, magnetic nanoparticles and photosensitizers that are simultaneously and remotely activated by external physical stimuli (a magnetic field and light), scientists at the Laboratoire ...

Scientists convert microbubbles to nanoparticles

Mar 30, 2015

Biomedical researchers led by Dr. Gang Zheng at Princess Margaret Cancer Centre have successfully converted microbubble technology already used in diagnostic imaging into nanoparticles that stay trapped in tumours to potentially ...

Designer's toolkit for dynamic DNA nanomachines

Mar 26, 2015

The latest DNA nanodevices created at the Technische Universitaet Muenchen (TUM)—including a robot with movable arms, a book that opens and closes, a switchable gear, and an actuator—may be intriguing ...

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.