Novel Fluorescent Probe for Selective Recognition of G-Quadruplex Based on Aggregation Induced Emission

G-quadruplex (G4) is four-stranded noncanonical secondary DNA structures, which have been identified as potential targets for therapeutic intervention. It is crucial to detect G4 and search for ligands that target G4 with high selectivity in complex biological matrices. The fluorescence signals and circular dichroism spectrum changes were explored for the interaction between jatrorrhizine chloride (Jat), a naturally aggregation-induced emission (AIE) molecule, and various DNA secondary structures. The fluorescence emission intensity was dramatically enhanced after Jat binding to G4 (AA22 as model analyte) compared with other configuration of DNAs, such as single-strand DNA (ssDNA), duplex DNA (dsDNA), hairpin DNA, and i-motif DNA were firstly reported. This means that Jat can serve as a fluorescence probe for the specific recognition of G4 DNA from other DNAs. A label-free AIE-based DNA biosensor to demonstrate the feasibility of detecting DNA polymerase activity and the screening of polymerization-targeted drugs was developed in this paper. The limit of the detection for DNA polymerase activity was 0.007 U·mL⁻¹. The results proved that the sensing system has high sensitivity and reproducibility for detection of DNA polymerase activity and can be used for screening DNA polymerase inhibitors based on specific recognition of G4 DNA. In all, it has potential for practical application in chemical and biomedical fields.