Thermal stabilization of nuclei acid nanoparticles (NANPs) using light-assisted drying

Abstract

Cold storage can be challenging and expensive for the transportation and storage of biologics. We are developing a new processing technique, light-assisted drying (LAD), to prepare biologics for anhydrous storage in a trehalose amorphous solid matrix. Nucleic acid nanoparticles (NANPs) are an example of new biological products that require refrigeration. DNA and RNA have emerged as building blocks for versatile biological drugs, called therapeutic nucleic acids (TNAs). NANPs have been developed to simultaneously deliver multiple TNAs and to conditionally activate TNAs and control their immunorecognition. The structural and chemical instability of NANPs over long-term storage at ambient temperatures is a challenge that may hamper broad use of this promising technology. In this work we apply the LAD technique to NANPs. NANPs suspended in a droplet of trehalose solution are irradiated with a near-IR laser to accelerate drying. As water is removed, the trehalose forms a protective matrix. The laser allows for careful control of sample temperature during processing. This is important as NANPs are thermally sensitive. In this study, RNA cubes (a type of NANP) were LAD processed and then stored for 1 month. Damage to LAD-processed NANPs was assessed after storage using gel electrophoresis and compared to unprocessed controls stored at 4°C. The thermal histories of samples were monitored during processing to determine the importance of temperature excursions on NANP viability after processing. The trehalose matrix was characterized using polarized light imaging to determine if crystallization occurred during storage, damaging embedded NANPs. These preliminary studies indicate that LAD processing can stabilize NANPs for dry-state storage at room temperatures.