2, Air Force Research Laboratory (AFRL), Dayton, Ohio, United States
3, Tufts University, Medford, Massachusetts, United States
Development of synthetic membranes is an emerging field in biomaterials research because of its potential for creating artificial cells that can withstand a variety of environments and have augmented functions that are otherwise limited in natural cells. Silk fibroin has many benefits including robust mechanical properties, controllable degradation rate, ease of functionalization, and ability to undergo prolonged exposure to UV light without complete degradation. Due to these properties, silk fibroin is a promising material to create shells that encapsulate DNA, in order to take the first steps towards a synthetic membrane that minimizes DNA damage and denaturation. This study focused on the encapsulation of plasmid DNA with polylysine-functionalized silk fibroin, to provide enhanced protection of the plasmid DNA, and then subjecting it to damaging environments, specifically UV radiation. Encapsulation of the plasmid DNA was achieved using the layer-by-layer fabrication method to create polylysine-functionalized silk fibroin shells around individual plasmid DNA molecules and conducting an in-depth characterization before and after exposure to UV light, using UV spectroscopy, zeta potential, atomic force microscopy, and gel electrophoresis. Changes to the plasmid DNA structure without silk encapsulation were analyzed, i.e. from its native, supercoiled form to its damaged, open circular form, and compared to encapsulated plasmid DNA. This study demonstrated that plasmid DNA encapsulated in polylysine-functionalized silk fibroin shells incurred less damage than unprotected DNA when exposed to UV light.