Cloaked Delivery System Designed to Kill Tumors from Within

Researchers have demonstrated that they can deliver a dormant toxin into a specific site such as a tumor for anticancer therapy, then chemically trigger the toxin to de-cloak and attack from within. It holds promise as an advanced synthetic, therapeutic drug delivery system for living cells.

An article describing the new host-guest chemistry application, led by University of Massachusetts Amherst (MA, USA) chemist Dr. Vincent Rotello and colleagues, with Dr. Lyle Isaacs at the University of Maryland (College Park, USA), was published in the October 2010 issue of the journal Nature Chemistry. As Dr. Rotello explained, "Supramolecular chemistry focuses on understanding what forces make molecules stick together, and using these forces to control the assembly of functional systems. This assembly process is much like Lego blocks, where bumps and dimples interact to hold biomolecules like DNA and proteins together.”

Specifically, Dr. Rotello and colleagues covered specialized gold nanoparticles with ligand or binding molecules (the bump) that made the particles toxic. These ligands, however, also can strongly bind to a hollow, bowl-shaped molecule (the dimple to which the bump sticks) called a cucurbituril that can make the particle nontoxic. When the gold nanoparticles are introduced into living cells, they lie dormant. The researchers then use another molecule that binds strongly to the dimple-shaped cucurbiturils, pulling them away from the gold nanoparticle so it becomes uncloaked and toxic.

"This triggered toxicity opens up new directions for controlled chemotherapeutics, where toxicity can be tuned by and directed through choice and amount of added activator,” Dr. Rotello stated. "They would be capable of achieving higher levels of site-specific activity with reduced collateral damage to surrounding healthy cells.”

The researchers are now examining this strategy in cells and will be moving to in vivo systems soon to explore comprehensively issues related to real-world application of the system.

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University of Massachusetts Amherst
University of Maryland