Study: Nanoparticles+imaging can seek out, kill cancer cells

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Researchers at Rice University and Baylor College of Medicine in Houston have reportedly developed a nanoparticle that integrates multiple functionalities by providing the ability to enhance two different imaging technologies simultaneously--fluorescence optical imaging and MRI--that may allow for diagnosis and treatment of tumors.

The nanoparticles, which are based on nanoshells invented by co-author Naomi Halas, PhD, a professor in electrical and computer engineering and a professor of chemistry and biomedical engineering at Rice, are said to have the ability to be tracked in real time with MRI as they seek out cancer cells, tag them with a fluorescent dye and kill them with heat.

The research was published online in Advanced Functional Materials.

Halas teamed up with Amit Joshi, PhD, an assistant professor in Baylor's division of molecular imaging, in creating the nanoparticles. Taking her original nanoshells, which convert otherwise harmless laser light into tumor-killing heat, Joshi and Halas modified the nanoshells by adding a fluorescent dye that glows when struck by near-infrared (NIR) light.

A graduate student of Halas, Rizia Bardhan, discovered that if the dye molecules were attached by leaving a small gap between the molecule themselves and the surface of the nanoshell, 40-50 times more light would be given off by the fluorescent particles. Rather than leave the small gap (the width of a few nanometers), Bardhan added iron oxide to the space that could be found by MRI, providing physicians using NIR imaging a way of diagnosing cancers without requiring surgery.  In addition, researchers added an antibody to the particles that allow them to bind to ovarian and breast cancer cells.     

The researchers conducted their study on laboratory cultured cells, as the method has not yet gained FDA approval. The findings of the study confirmed that the fluorescent particles tracked down cancer cells and destroyed them with heat.

Despite the positive results of the research thus far, Joshi estimates the testing of the method in humans is a least two years away, with the hope of destroying entire tumors in live animals.

Joshi noted a proposed system in which patients via injection will be administered a dose of nanoparticles, containing antibodies tailored for each patient’s cancer case.  Physicians would then be able to observe the path of the nanoparticles, as well as chart their progress in killing tumors with heat by way of NIR imaging and/or MRI.

"This particle provides four options -- two for imaging and two for therapy," Joshi said. "We envision this as a platform technology that will present practitioners with a choice of options for directed treatment."

The researchers’ plan is to develop different versions of the nanoparticles, designed to be cancer stage-specific, with an emphasis on early-stage cancer.  Different antibodies will also be utilized in further tailoring the particles to the various stages and forms of cancer.

On the road toward FDA approval, Halas noted that adding MRI functionality to particle testing is a “promising” way to achieve approval.

Moreover, the new nanoparticle has been carefully created by the utilization of existing components which have been approved for medical use or currently in use by clinical trials, said Halas.

The particle is considered an example from a emergent field called "theranostics," which develops technologies physicians can use to diagnose and treat diseases in a single procedure, said the researchers.