A disaggregation-driven BODPIY-based probe for ratiometric detection of G4 DNA

In conventional systems, fluorescent probes with planar structures usually experience the phenomenon of aggregation-induced quenching (ACQ) that limits their practical applications in bio-medical sensing. To confront such problem, an attractive way is to develop a disaggregation-induced emission (DIE) sensing strategy, where the quenched fluorescence is recovered via a disaggregation process. Currently most of the fluorescent probes designed based on DIE mechanism are signal off-on type with the fluorescent intensity changed at a single wavelength. On the other hand, ratiometric fluorescent probes have the advantage of having two distinct emission wavelengths, effectively avoiding environmental interference. The DIE probes with a ratiometric fluorescence response still poorly established. Herein, we report a BODIPY-based probe BODPA, where a 2,2′-dipicolylamine group was introduced to the meso-position of BODIPY core, for the selective ratiometric detection of G-quadruplex (G4) DNA. This probe in buffer solution formed aggregates with weak fluorescence at 508 nm. In the presence of G4 DNA, bright fluorescence was emitted at 518 nm through DIE mechanism. Taking advantage of the ratiometric manner, probe BODPA exhibited selectivity for G4 DNA over duplex DNA. The binding details between probe BODPA and G4 DNA were assessed by spectroscopic and molecular modeling methods, which suggested the ability of this probe could coordinate with G4 structure via end stacking and partial groove binding mode.