Novel material could enable long term, controllable drug delivery

Researchers in the US have developed a new material and drug delivery mechanism that can slowly release medication over a period of several months.

It is thought that the breakthrough could one day lead to implants that would assist in the treatment of chronic pain, and in the prevention of recurring cancer tumours. The system consists of a biocompatible, highly porous, three dimensional polymer material containing a selected drug and a volume of air that slows infiltration from surrounding water. As water seeps into the material, it displaces the air, thereby gradually releasing the drug. "The idea was to create a 3D material that has polymer fibers throughout and air trapped within," said Professor Mark Grinstaff, who led the team. "If we can slow the penetration of water into the structure, it will slow the release of the drug." To prevent water from flooding the structure and causing an immediate release of the drug, Grinstaff and his colleagues designed the air filled, mesh-like material to be superhydrophobic. This meant that droplets of water barely touched the surface, and instead formed beads similar to those that appear on a freshly waxed car or on plant leaves. They produced the porous polymer mesh using a process called electrospinning, which overlays micron sized fibers upon one another. To control the rate of drug release, the researchers adjusted chemical and physical properties of the material so that the entrapped air was loosely or tightly held. The more tightly held the air was within the structure, the harder it proved for water to displace it. Equally, the slower the release was, the longer the treatment duration. Loaded with a widely used anti-cancer drug called SN-38 in in vitro experiments, the polymer mesh and internal air pocket proved to be robust and effective against lung cancer cells in solution for more than 60 days, indicating its suitability for long term drug delivery. The researchers now plan to conduct a series of in vivo experiments to evaluate the system's efficiency and potential clinical effectiveness. Grinstaff concluded: "Many researchers are advancing new drug delivery systems, and several others are designing superhydrophobic materials, but we're combining these disciplines to see if we can open up new doors and enable more effective treatments for a wide range of diseases."