The Application of Light-Assisted Drying to the Thermal Stabilization of Nucleic Acid Nanoparticles.

Background: Cold-chain storage can be challenging and expensive for the transportation and storage of biologics, especially in low-resource settings. Nucleic acid nanoparticles (NANPs) are an example of new biological products that require refrigerated storage. Light-assisted drying (LAD) is a new processing technique to prepare biologics for anhydrous storage in a trehalose amorphous solid matrix at ambient temperatures. In this study, LAD was used to thermally stabilize four types of NANPs with differing structures and melting temperatures. Methods: Small volume samples (10 μL) containing NANPs were irradiated with a 1064 nm laser to speed the evaporation of water and create an amorphous trehalose preservation matrix. Samples were then stored for 1 month at 4°C or 20°C. A FLIR C655 mid-IR camera was used to record the temperature of samples during processing. The trehalose matrix was characterized using polarized light imaging (PLI) to determine if crystallization occurred during processing or storage. Damage to LAD-processed NANPs was assessed after processing and storage using gel electrophoresis. Results: Based on the end moisture content (EMC) as a function time and the thermal histories of samples, a LAD processing time of 30 min is sufficient to achieve low EMCs for the 10 μL samples used in this study. PLI demonstrates that the trehalose matrix was resistant to crystallization during processing and after storage at 4°C and at room temperature. The native-polyacrylamide gel electrophoresis results for DNA cubes, RNA cubes, and RNA rings indicate that the main structures of these NANPs were not damaged significantly after LAD processing and being stored at 4°C or at room temperature for 1 month. Conclusions: These preliminary studies indicate that LAD processing can stabilize NANPs for dry-state storage at room temperature, providing an alternative to refrigerated storage for these nanomedicine products.