RNA Protection is Effectively Achieved by Pullulan Film Formation

RNA is a functionally versatile polymer but suffers from susceptibility to spontaneous or RNase-catalyzed degradation. This vulnerability makes it difficult to preserve RNA for extended periods of time, which limits its use in various contexts, including practical applications of functional nucleic acids. Here we present a simple method to preserve RNA by pullulan (a complex sugar produced by Aureobasidium pullulans fungus) film formation. This strategy can markedly suppress both spontaneous and RNase-promoted degradation. More importantly, the pullulan film readily dissolves in aqueous solutions allowing retrieval of fully functional RNA species. To illustrate the advantage of this protective method for practical applications, we have engineered a simple paper sensor device containing a bacteria-detecting RNA-cleaving DNAzyme. This device exhibits unchanged detection capability after regular storage at room temperature for six months.