Nanofiber patches have the potential to significantly change drug-delivery systems. University of Akron professors Daniel Smith (chemistry) and Darrell Reneker (polymer science), are developers of a patented technology, which makes possible the controlled release of drugs to a specific area of the body.

Licensed by SNS Nano Fiber Technology, the patented technology allows the incorporation of additives as well as the sequestering of reactants throughout a nanofiber matrix. The nanofiber matrix, known as Nanosan, is composed of polymer fibers with diameters that are less than 1% of a human hair (average hair width, about 100µm). A range of particles may be entrapped throughout or encapsulated within the nanofibers. The size of the particles will influence the method of incorporation. A variety of polymer nanofibers can be fabricated as well: water-soluble, biodegradable, biocompatible, bioresorbable, elastic, flexible or brittle, hydrophilic or hydrophobic. Therefore, a drug-delivery system can be custom designed to enhance the efficacy of a drug and its delivery.

Fluorescent image of polymer nanofibers containing fluorescently labeled albumin. Inset shows SEM (scanning electron microscope) image of nanosan crossection.

One example is that of reactants that have been composited in a nanofiber patch, which upon reacting characteristically produce nitric oxide (NO) almost instantaneously. Both reactants are contained in the matrix, but they're separated by nanofibers containing an inert component. This postpones the reaction until the nanofiber patch is activated via hydration immediately prior to application. Reactants then migrate slowly through the nanofiber matrix. Their reaction results in the release of nitric oxide gas for a period of 6 to 8 hours.

Nitric oxide has several therapeutic properties. For instance, as a vasodilator, it controls the flow of blood to tissues, helping to heal wounds. It also kills bacteria as well as viruses. Because the patch can be placed directly on a wound or lesion, only targeted areas receive the treatment. Furthermore, patches can be made with various amounts of reactants, so the dose can be adjusted as needed.

The production of nitric oxide for the treatment of lesions or wounds is just one possibility for this type of drug-delivery vehicle. Another solves a common problem with superabsorbent particles and a phenomenon called gel-blocking. In it, particles that initially encounter the fluid absorb to their fullest capacity, creating swollen regions around the edges that then block particles on the inside from exposure to the fluid, thereby decreasing the overall absorption. By dispersing particles throughout the nanofiber matrix, all particles gain access to the fluid to maximize the absorption efficiency. Nanofiber mats that contain superabsorbent particles can be used as wound dressings, with or without additives. The particles absorb fluid from the wound bed, while keeping it sufficiently moist.

Other additives such as antimicrobials and antibacterials can be incorporated when needed. Composite fibers, made of different types of polymers, also can be produced. One polymer can be water-soluble, while the other is not. This allows a small particle that is encapsulated within the fiber to have a larger contact area by dissolving away the water-soluble polymer, leaving behind the insoluble polymer to retain the structure of the material.

With so many design options, a little fiber goes a long way.