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Preliminary studies have shown that silk fibroin can protect biomacromolecules from thermal degradation, but a deeper understanding of underlying mechanisms needed to fully leverage the stabilizing potential of this matrix has not been realized. In this study, we investigate stabilization of plasma C-reactive protein (CRP), a diagnostic indicator of infection or inflammation, to gain insight into stabilizing mechanisms of silk. We observed that the addition of antiplasticizing excipients that suppress β-relaxation amplitudes in silk matrices resulted in enhanced stability of plasma CRP. These observations are consistent with those made in sugar-glass-based protein-stabilizing matrices and suggest fundamental insight into mechanisms as well as practical strategies to employ with silk protein matrices for enhanced stabilization utility. [ABSTRACT FROM AUTHOR]

The use of mRNA and miRNA as diagnostic parameters and therapeutic agents has drawn wide interest both clinically and in research. However, RNA is a labile molecule, which requires strict storage conditions, often including cold temperatures or dry environments, in order to preserve RNA integrity. Achieving this requires huge costs for storage and added difficulty in transport. To address these issues, we introduce a system to encapsulate and store it long-term in dried silk fibroin matrices. At temperatures up to 45 °C, mRNA samples stored in lyophilized silk matrices showed good stability over 1 week, as measured by real-time PCR to assess transcript recovery. While the presence of the silk interfered with the generation of cDNA required for quantitation at roughly 1% w/v (400:1 silk:RNA mass), this phenomenon was resolved by the use of commercial RNA purification kits for silk concentrations up to 4% w/v. A higher concentration of silk correlated with increased thermal protection. As an alternative to lyophilization, RNA was simply air-dried in the presence of aqueous fibroin to create storage matrices. While air-dried matrices composed of low silk content were not protective, higher concentrations were protective and progressively lost additional water over time of storage because of the overall hydrophobic nature of the system. Taken together, these findings provide a new and potentially simpler method for preserving RNA samples for long-term storage and transportation, acting primarily on a water exclusion mechanism.