One-step isothermal RNA detection with LNA-modified MNAzymes chaperoned by cationic copolymer

RNA detection permits early diagnosis of several infectious diseases and cancers, which prevent propagation of diseases and improve treatment efficacy. However, standard technique for RNA detection such as reverse transcription-quantitative polymerase chain reaction has complicated procedure and requires well-trained personnel and specialized lab equipment. These shortcomings limit the application for point-of-care analysis which is critical for rapid and effective disease management. The multicomponent nucleic acid enzymes (MNAzymes) are one of the promising biosensors for simple, isothermal and enzyme-free RNA detection. Herein, we demonstrate simple yet effective strategies that significantly enhance analytical performance of MNAzymes. The addition of the cationic copolymer and structural modification of MNAzyme significantly enhanced selectivity and activity of MNAzymes by 250 fold and 2,700 fold, respectively. The highly simplified RNA detection system achieved a detection limit of 73 fM target concentration without additional amplification. The robustness of MNAzyme in the presence of non-target RNA was also improved. Our finding opens up a route toward the development of an alternative rapid, sensitive, isothermal, and protein-free RNA diagnostic tool, which expected to be of great clinical significance.