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.