Light-assisted drying (LAD) for anhydrous preservation of biologics: processing sample volumes comparable to a therapeutic dose

Protein-based products have been developed to treat a range of conditions and are used in vaccines and assays. A challenge in the development of these products is maintaining the protein in the folded state during processing and storage. The most common method of stabilizing proteins for storage is lyophilization. However, this process remains expensive and many proteins that are lyophilized must be refrigerated or frozen to maintain functionality. Cold-chain storage can be challenging and expensive for the transportation and storage of biologics, especially in low-resource settings. Recent research has demonstrated that anhydrous preservation in a trehalose amorphous solid matrix offers an alternative to freeze drying for the preservation of biologics. We have previously described a new processing technique, light assisted drying (LAD), to create trehalose preservation matrices of small volume (40 mu L) samples. LAD uses illumination by near-infrared laser light to selectively heat water and speed dehydration. In this study we apply the LAD technique to large volume samples (250 mu L) that are more comparable to therapeutic doses. A model protein, lysozyme, was LAD processed then stored for 1 month. The end moisture content of samples was determined immediately after processing and then again after storage. The thermal histories of samples were monitored during processing to determine the optimal drying time. The trehalose matrix was characterized using polarized light imaging to determine if crystallization occurred during storage, damaging embedded proteins. These preliminary studies indicate that LAD can effectively stabilize large volume samples.