Novel Chlorophyll-Based Nanoparticles Generate New Options for Detection and Treatment of Cancer

Researchers have combined chlorophyll and lipid to create nanoparticle vesicles that respond to both light and sound while maintaining the capability to transport drugs actively or passively for treatment of cancer or other chronic conditions.

Investigators at Princess Margaret Hospital (Toronto, Canada) described the development of porphysomes, nanovesicles formed from self-assembled porphyrin (chlorophyll/lipid) bilayers in a paper published in the March 20, 2011, online edition of the journal Nature Materials.

The novel porphysomes generated large, tunable fluorescence extinction coefficients, structure-dependent fluorescence self-quenching, and unique photothermal and photoacoustic properties. When used in conjunction with photoacoustic tomography, porphysomes enabled the sensitive visualization of cells in the lymphatic system. Porphysomes were enzymatically biodegradable and were minimally toxic to mice.

In a similar manner to liposomes, the large aqueous core of porphysomes could be loaded passively or actively with drugs or other compounds. Following systemic administration, porphysomes accumulated in tumors of xenograft-bearing mice, and laser irradiation induced photothermal heating that killed the tumors.

"There are many nanoparticles out there, but this one is the complete package, a kind of one-stop shopping for various types of cancer imaging and treatment options that can now be mixed and matched in ways previously unimaginable,” said senior author Dr. Gang Zheng, associate professor of medical biophysics at Princess Margaret Hospital.

"In the lab, we combined two naturally occurring molecules (chlorophyll and lipid) to create a unique nanoparticle that shows promise for numerous diverse light-based (biophotonic) applications. The structure of the nanoparticle, which is like a miniature and colorful water balloon, means it can also be filled with drugs to treat the tumor it is targeting. The unprecedented safety of this nanoparticle in the body is the icing on the cake. We are excited by the possibilities for its use in the clinic.”

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