Certain embodiments provide RNA nanostructure (e.g., comprising one single-stranded RNA (ssRNA) molecule, wherein the RNA nanostructure comprises at least one paranemic cohesion crossover), as well as compositions and methods of use thereof. In certain embodiments, such RNA nanostructures are immuno-stimulatory or immuno-modulatory.某些實施例提供RNA奈米結構(例如,包含一種單鏈RNA(ssRNA)分子,其中該RNA奈米結構包含至少一個平行內聚交叉),以及其組合物及使用方法。在某些實施例中,該等RNA奈米結構具免疫刺激性或免疫調節性。