February 13, 2009: Nanosys Inc. has announced results of its initial studies using a novel silicon nanowire mucous membrane drug delivery device. These devices have a nanostructured surface that relies on adhesive properties known in physics as van der Waals forces of adhesion.

Results of initial studies published in the American Chemical Society’s Nano Letters, outline the device’s ability to significantly improve drug delivery to mucous membranes such as those in the nose, intestine, eyes, vagina and mouth.

Mucous membranes have long been a target for drug delivery due to their large surface area and rich blood supply. However, nature has designed these membranes to also be efficient barriers to foreign substance penetration, such as drugs. Mucus, which is constantly produced by these tissues, is moved across the surface by tiny beating hair-like structures called cilia

Removal of a substance floating in the mucus of the nasal cavity can be as fast as 10 minutes, for example. Previous attempts at overcoming this barrier function relied on chemical modification of the delivery vehicle to better adhere to binding elements within the mucus. Nanosys’ silicon nanowires will adhere instead to the cells underneath the mucus, the actual targets for drug delivery. This critical feature allows for a longer residence time, improved local concentrations and better absorption of target drugs by the tissues, Nanosys said in a news release.

The team, led by Hugh Daniels at Nanosys and Tejal Desai and Kayte Fischer at the University of California, San Francisco, also quantified the amount of mucosal shear force the silicon nanowire-based devices could withstand before being eliminated, and demonstrated it to be at least 100-fold better than a non-silicon nanowire device.

(Source: Nano Letters)