Programmed Drug Release
Novel coatings could make safer implants, help build organs
Source: “Controlling Interlayer Diffusion to Achieve Sustained, Multiagent Delivery from Layer-by-Layer Thin Films”
Kris C. Wood et al.
Proceedings of the National Academy of Sciences 103(27): 10207-10212
Results: By developing a way to segregate components in ultrathin surface coatings, MIT researchers have made a new class of materials that can release drugs, and even genes, in an exact sequence and at a predetermined rate.
Why it matters: Coated with the new materials, medical implants such as artificial hips could prove safer and more effective than their predecessors, releasing first antibiotics and then growth factors and other drugs exactly where and when they are needed. Efforts to engineer complex tissues such as bones, blood vessels, muscles, and livers could also benefit from scaffolds coated with the new materials, which could encourage the growth of specific cell types.
Methods: The researchers dip a surface to be coated into a series of solutions alternately containing polymers of one charge and drugs or drug carriers of the opposite charge. These layered coatings will break down in water, freeing their contents. To prevent all the layers from breaking down at once, the researchers separate them with boundary layers of covalently linked molecules. The scientists believe that a given boundary layer will peel off after it has been exposed to water; but that doesn’t happen until the layer above it has completely dissolved. The result is an ordered, sequential release of drugs, its timing dependent on the number of layers.
Next steps: The researchers are now developing coatings that incorporate a specific sequence of therapeutics for orthopedic applications, such as hip implants, which will then be tested for safety and efficacy.