All DNAs were ordered from Tsingke Biotechnology (Beijing, China). Fluorescence was measured on a FluoroMax + spectrofluorometer (Horiba Scientific) using FluorEssence software (v.3.9). Fluorescence imaging was acquired on an Olympus SpinSR10 microscope (Olympus). Data were plotted using Origin 2021 software. All RNA-binding fluorophores, including HBC, HBC620, BI, DFHO and tetramethyl rhodamine-dinitroaniline (TMR-DN) used in this study were synthesized as described previously (25 (link),34 (link),35 (link)).