General Method for Generating Circular Gradients of Active Proteins on Nanofiber Scaffolds Sought for Wound Closure and Related Applications.

Scaffolds functionalized with circular gradients of active proteins are attractive for tissue regeneration because of their enhanced capability to accelerate cell migration and/or promote neurite extension in a radial fashion. Here, we report a general method for generating circular gradients of active proteins on scaffolds composed of radially aligned nanofibers. In a typical process, the scaffold, with its central portion raised using a copper wire to take a cone shape, was placed in a container (upright or up-side-down), followed by dropwise addition of bovine serum albumin (BSA) solution into the container. As such, a circular gradient of BSA was generated along each nanofiber. The bare regions uncovered by BSA were then filled with an active protein of interest. In demonstrating their potential applications, we used different model systems to examine the effects of two types of protein gradients. While the gradient of laminin and epidermal growth factor accelerated the migration of fibroblasts and keratinocytes, respectively, from the periphery toward the center of the scaffold, the gradient of nerve growth factor promoted the radial extension of neurites from the embryonic chick dorsal root ganglion. This method for generating circular gradients of active proteins can be readily extended to different types of scaffolds to suit wound closure and related applications that involve cell migration and/or neurite extension in a radial fashion.