Moisture content impacts the stability of DNA adsorbed onto gold microparticles

Particle‐mediated epidermal delivery (PMED) of small quantities of DNA (0.5-4.0 μg) has been reported to both induce an immune response and protect against disease in human subjects. In order for the PMED of DNA to be a viable technique for vaccination, the adsorbed DNA must be stable during shipping and storage. Here, we report that the storage stability of plasmid DNA adsorbed to 2‐μm gold particles is strongly dependent on sample water content. Gold/DNA samples stored at 60°C and 6% relative humidity (RH) maintained supercoil content after 4‐month storage, whereas storage at higher RHs facilitated degradation. Storage with desiccants had stabilizing effects on DNA similar to storage at 6% RH. However, storage with “indicating” Drierite and phosphorus pentoxide resulted in enhanced rates of DNA degradation. © 2011 Wiley‐Liss, Inc. and the American Pharmacists Association J Pharm Sci 100:4845-4854, 2011