Nanoparticles and drug delivery gel together

While still in its infancy, the nanogel was believed to be an "ideal drug delivery tool"​, according to Carnegie Mellon University scientists developing the product. Only 200 nanometers in diameter, the nanogel is a cross-linked water swellable particle that has been created by atom transfer radical polymerization (ATRP), a controlled polymerization process of commercially available monomers, which controls every aspect of composition, architecture and functionality. The resulting uniform network of cross-linked polymer chains, based on an analogue of poly(ethylene oxide), has a number of properties which have made the particle attractive for drug delivery. "There are two advantages to this system,"​ Carnegie Mellon University Center for Macromolecular Engineering associate director Jim Spanswick told US-PharmaTechnologist.com. "One is the ability to tailor the interior of the gel particle to be compatible with the drug and control the rate of release of the drug at the targeted biological disease site. The other is the freedom to conjugate any targeting agent to the outside of the nanogels allowing it to circulate throughout the body to find targeted agents." ​ The biodegradable nature of the links and the composition of the monomer units making up the core of the gel meant the nanogel could release the drug in a controlled way in a particular location. The uniform nature of the particle allowed the gel to degrade in a uniform and predictable manner, Spanswick said. In the scientists' research, which was recently published in the Journal of the American Chemical Society, the nanogels biodegraded into water-soluble polymers in the presence of glutathione tripeptide, which is commonly found in cells. The biodegradation triggered the release of the anticancer drug doxorubicin, which was used in the research. The team has also used the drug rhodamine isothiocyanate-labeled dextran. The ATRP process also allowed the exterior of the particle to be manipulated so as to incorporate a targeting functionality on the surface that could interact with specific cell receptors. "The advantage of site specific targeted drug delivery is that very toxic drugs could be delivered to the targeted site with little or no damage to surrounding tissues. The amount of delivered drug would be the minimum required to remove the pathogen,"​ Spanswick said. The nanogels can also escape the notice of the body's immune system because their physical size is below that which is detected by the body. While cancer research is driving the development of the drug delivery system, Spanswick said any drugs could be encapsulated into the gel particle. "The [chemical makeup] of the core can be varied to allow encapsulation of hydrophilic agents like carbohydrates or more hydrophobic drugs if required." ​ Depending on the target organ, the gel could be administered either orally, intravenously or as a spray, he said, and there could potentially be other applications. "This is still a dream, but since functional identifying materials, imaging materials and site specific drug delivery can all individually be incorporated into the nanogels, they could be used for detection of illness, such as cancer, imaging of the site of infection and site specific treatment. This would allow very early detection of serious illness and site specific chemotherapy." ​ The next step was starting animal in vivo studies, Spanswick said.