A split G-quadruplex-specific dinuclear Ir(III) complex for label-free luminescent detection of transcription factor

A group of luminescent dinuclear Ir(III) complexes were synthesized to study the application possibility as luminescent G-quadruplex (G4) sensors. According to the results, the dinuclear Ir(III) complexes 1-5 were assessed as selective G4 sensors. Among them, complex 5 not only demonstrates the highest specificity towards G4, but also shows linearly enhanced luminescent intensity with the increase of split G4 concentration. Complex 5 was thus utilized to establish a label-free split G4-based detection platform for luminescent detection of transcription factor (TF). This luminescent assay is simple and sensitive with the detection limit of 0.027 nM for NF-kappa B p50 in aqueous solution. The split G4-based TF sensing platform also worked well in diluted human serum, demonstrating high application potential for biological sample analysis.