Recent Advancements in Nanosystem-Based Molecular Beacons for RNA Detection and Imaging

As one of the two nucleic acids used by extant biochemistry, RNA is of great importance for cellular function and development, and its expression can affect cell homeostasis. Therefore, accurate detection of RNA is the key contributor to disease diagnosis, including tumor detection. Compared with conventional RNA detection methods, molecular beacons (MBs) have high selectivity for target molecules detection, which have been widely used in RNA detection. However, the background fluorescence of typical MBs will seriously affect the detection sensitivity and accuracy. In addition, the poor affinity and weak resistance to the nuclease digestion of MBs also limit its applications. With the development of nanotechnology, many nanomaterials with fluorescence quenching ability have been widely used as quenchers and carriers for MBs to construct nanoprobes (Nano-MBs). In this review, we summarize the recent developments of Nano-MBs in RNA detection and imaging over the past decade. First, the structure, working principle, and classification of MBs are discussed. Then, we introduce several typical Nano-MBs based on gold nanoparticles, polydopamine, graphene oxide, molybdenum disulfide, and quantum dots. Particular emphasis is placed on the application of Nano-MBs in mRNA and miRNA detection and imaging in the diagnosis and treatment of diseases, as well as in cancer. Finally, the current challenges and future perspectives are also discussed.