Abstract: Rapid classification of the secondary structures of nucleic acids, such as G-quadruplexes(G4s) is desirable but very challenging due to the high similarity among different folding. Chen et al. constructed a host-guest sensor array to differentiate the topology of unmodified G4s for the first time. Multiple equilibria present in the sensing system resulted in differential fluorescence responses to different G4 structures, and yielded excellent selec-tivity of the sensor array in structure discrimination. The corresponding research has been published in Nature Chemistry and can be accessed at https://doi.org/10.1038/s41557-021-00647-9.