Multifunctional red-emissive AIEgens as DNA-intercalating ligands: dual sensing of pH and viscosity accompanied by tissue imaging†

Abstract

The best antimicrobials and cancer therapies intercalate DNA-binding compounds to target DNA-processing proteins. We developed a DNA intercalator ligand that addresses the aggregation to speed up the development of novel intercalating medications. This DNA-intercalating ligand allows cellular imaging with little background interference due to its aggregation-induced emission (AIE) and colorimetric pH-responsiveness. These properties make it a versatile biosensor. The ligand exhibits robust intercalative binding with DNA at a 52.6 nM concentration and a high affinity of 55.46 × 10⁶ M⁻¹, ensuring sensitivity to low DNA concentrations. By changing its emission intensity and spectrum features with viscosity, the ligand may sense its microenvironment's physical parameters. It also changes color when pH changes, making pH monitoring easy and noticeable. We studied its DNA interaction using absorbance, fluorescence, and circular dichroism spectroscopy. To determine the mechanism, we performed dye-displacement tests, melting temperature investigations, and iodide quenching. Red fluorescence, high-affinity DNA intercalation, aggregation-induced emission (AIE), viscosity sensitivity, and pH-dependent colorimetric response make this ligand a promising candidate for DNA-targeted imaging and pH-sensitive biosensing in biological and environmental applications. Plant cell tissue imaging has also proved successful.