Researchers from North Carolina State University and the University of North Carolina at Chapel Hill have developed a drug delivery technology that consists of an elastic patch that can be applied to the skin and will release drugs whenever the patch is stretched.
For example, if applied to the elbow, the patch would release a drug when the elbow bends and stretches the patch. ‘This could be used to release painkillers whenever a patient with arthritic knees goes for a walk, or to release antibacterial drugs gradually as people move around during the course of a day,’ says Zhen Gu, co-senior author of a paper describing the work and an Assistant Professor in the joint biomedical engineering programme at NC State and UNC-Chapel Hill.
The technology consists of an elastic film that is studded with biocompatible microcapsules. These microcapsules, in turn, are packed with nanoparticles that can be filled with drugs.
Functionally, the microcapsules stick halfway out of the film, on the side of the film that touches a patient’s skin. The drugs leak slowly out of the nanoparticles and are stored in the microcapsules. When the elastic film is stretched, it also stretches the microcapsules – enlarging the surface area of the microcapsule and effectively squeezing some of the stored drug out onto the patient’s skin, where it can be absorbed.
'When the microcapsule is stretched from left to right, it is also compressed from bottom to top,' says Yong Zhu, co-senior author of the paper and an Associate Professor of mechanical and aerospace engineering at NC State. ‘That compression helps push the drug out of the microcapsule.’ After being stretched, the microcapsule is recharged by the drugs that continue to leak out of the nanoparticles.
The researchers also incorporated microneedles into the system, applying them on top of the microcapsules. In this configuration, the drugs can be squeezed through the microneedles.
‘We’re now exploring how this tool can be used to apply drugs efficiently and effectively to burn patients, and we plan to look at how this could be used for pain relief as well. The materials are relatively inexpensive and the manufacturing process is fairly straightforward, so we’re optimistic that this could be scaled up in a cost-effective way,’ Zhu says.