Nov 27, 2013

Research by the Zink Group (Tania Guardado-Alvarez, Melissa Russell, and Prof. Jeff Zink) and Schwartz Group (Dr. Lekshmi Sudah Devi and Prof. Ben. Schwartz) was spotlighted by the Journal of the American Chemical Society (JACS).

JACS: Light Flips Open a Snap-Top Silica Nanocontainer  (Leigh Krietsch Boerner, Ph.D.)

When designing a drug to be used in the body, such as a chemotherapy drug, releasing the medicine at the right place and time is very important. However, there are few systems that have a convenient or selective trigger. Jeffrey Zink and colleagues have found a way to use light to release drug molecules from a nanoparticle “bottle” (DOI: 10.1021/ja407331n).

Photocleavage mechanism of the snap-top cap. Final products are shown on the right.
Light is an effective trigger for selective drug release—biological tissue is transparent to red wavelengths—and molecules exhibiting two-photon absorption are particularly good candidates, because these compounds absorb red wavelengths. In earlier studies, scientists tried to construct prodrugs, attaching the active molecule to a carrier by a photolabile connection. However, this type of synthesis can be difficult, time-consuming, and expensive.
Another approach is to encapsulate drug molecules inside nontoxic mesoporous silica nanoparticles. Here, Zink and co-workers cap the ends of these silicia drug “bottles” with a molecule that can be photoactivated to move on demand. The “snap-top” is a bulky β-cyclodextrin molecule that is attached to the silica nanoparticle with a photo-cleavable stalk. The researchers find they can break this bond with either one photon or two, releasing both the cap and the cargo inside. This discovery may lead to cancer drug treatment that is more targeted and has fewer side effects.