Circularly Polarized Luminescence of Achiral Cyanine Molecules Assembled on DNA Templates

The exploration of biocompatible materials with circularly polarized luminescence (CPL) activity is becoming an attractive topic due to the great potential application in biosensing and bioimaging. Here, we describe a strategy to fabricate new CPL-active bio-materials using achiral carbazole-based biscyanine fluorophores coassembled with chiral deoxyribonucleic acid (DNA) molecules. This cyanine molecule has been shown to behave as a DNA detecting probe, featuring strong fluorescent emission induced by restriction of intramolecular rotation (RIR). When the achiral cyanine molecules are bound to the minor groove of DNA via electrostatic attraction in aqueous solution, the chirality of the DNA molecules can be transferred to the confined RIR cyanine dyes, triggering a remarkable circularly polarized luminescent emission. The chirality of the CPL signal can be regulated by the structures of the DNA templates. Stimuli-responsive CPL activates were observed from DNA-cyanine complexes. We further verified this strategy on different DNA-based nanomaterials, including DNA origami nanostructure. Our design presents a new avenue to fabricate compatible CPL materials.