A new thin-film coating developed at the Massachusetts Institute of Technology may serve as a “micro pharmacy”, delivering controlled drug doses to specific targets in the body following implantation. The film, typically about 150 nanometers (billionths of a meter) thick, can be implanted in specific parts of the body.

"You can mete out what is needed, exactly when it's needed, in a systematic fashion," said Paula Hammond, the Bayer Professor of Chemical Engineering and senior author of a paper on the work appearing in the Feb. 11 issue of the Proceedings of the National Academy of Sciences.

The films are made from alternating layers of two materials: a negatively charged pigment and a positively charged drug molecule, or a neutral drug wrapped in a positively charged molecule. The pigment, called Prussian Blue, sandwiches the drug molecules and holds them in place; Prussian Blue has been found safe for use in humans by the FDA.

When an electrical potential is applied to the film, the Prussian Blue loses its negative charge, which causes the film to disintegrate, releasing the drugs. The amount of drug delivered and the timing of the dose can be precisely controlled by turning the voltage on and off. The electrical signal can be remotely administered (for example, by a physician) using radio signals or other techniques that have already been developed for other biomedical devices.

The films can carry discrete packets of drugs that can be released separately, which could be especially beneficial for chemotherapy. The research team is now working on loading the films with different cancer drugs.
Eventually, devices could be designed that can automatically deliver drugs after sensing that they're needed. For example, they could release chemotherapy agents if a tumor starts to regrow, or deliver insulin if a diabetic patient has high blood sugar.

Release date: February 11, 2008
Source: Massachusetts Institute of Technology