MIT nanoparticle takes advantage of tumors’ acidity to peel layers away

May 4th, 2011 - 6:10 pm ICT by ANI  

Washington, May 4 (ANI): A new type of drug-delivery nanoparticle developed at the Massachusetts Institute of Technology (MIT) hunts out the acidic environment that characterizes all cancer cells.

Such particles could target nearly any type of tumor, and can be designed to carry virtually any type of drug, said Paula Hammond, a member of the David H. Koch Institute for Integrative Cancer Research at MIT.

Like most other drug-delivering nanoparticles, the new MIT particles are cloaked in a polymer layer that protects them from being degraded by the bloodstream.

However, the MIT team, including lead author and postdoctoral associate Zhiyong Poon, designed this outer layer to fall off after entering the slightly more acidic environment near a tumor. That reveals another layer that is able to penetrate individual tumor cells.

Hammond and her colleagues decided to take advantage of tumor acidity, which is a byproduct of its revved-up metabolism.

To build their targeted particles, the researchers used a technique called “layer-by-layer assembly.” This means each layer can be tailored to perform a specific function.

When the outer layer (made of polyethylene glycol, or PEG) breaks down in the tumor’s acidic environment, a positively charged middle layer is revealed.

That positive charge helps to overcome another obstacle to nanoparticle drug delivery: Once the particles reach a tumor, it’s difficult to get them to enter the cells.

Particles with a positive charge can penetrate the negatively charged cell membrane, but such particles can’t be injected into the body without a “cloak” of some kind because they would also destroy healthy tissues.

They study has been published in the journal ACS Nano. (ANI)

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