RNA Kissing Loop Library to expand RNA Fiber functionality and control cargo load for potential intracellular siRNA delivery.

A kissing loop (KL) is an RNA motif that among others may have a 180° geometry when derived from a viral genome. The KL interactions of this geometry consist of nine base pairs, six of which are interacting in complementary binding while three are stacking for support of the geometry. In RNA nanotechnology, the rational design of nanoparticles is dependent on the canonical complementarity of nucleobases, where adenines bind uracils and guanines bind cytosines. The sequences of various components play a critical role in their intercompatibility with one another (or intracompatibility within a single self-folding strand) of the intermediate or final nanostructures, as their crosstalk or undesired interactions may hinder the assembly of components or the final nanostructure. This KL motif is important for its incorporation into larger RNA nanostructures as it functions as a "linker" to attach other RNA functionalities together. This work investigates the expansion of a single KL sequence to a KL library that can be intercompatible for use in a single nanostructure. This KL library would be crucial to assembling RNA vehicles with higher heterogeneous carrying capacity for therapeutic siRNAs or any other cargo into target cells.