G-quadruplex DNA regulates invertible circularly polarized luminescence†
Circularly polarized luminescence (CPL) has recently attracted great interest due to chiral optical applications; various materials have been developed as templates for CPL readout. Here, we demonstrate firstly CPL measurement of human telomeric G-quadruplex (Tel G4) and achiral fluorogenic dye (ThT) interaction, in which the chirality is transferred from G4 template to the binding molecules. Chiral CPL signals are sensitive to Tel G4 structures; not only the mirror D-/L-enantiomers, but also the parallel/antiparallel dynamic changes. Different DNA sequences and structures are statistically analysed to draw the conclusion that right-handed CPL is induced on the parallel G4 structure; whilst left-handed CPL is triggered on antiparallel G4 with opposite chirality directions. Inversion of polarity of G-quartets in various G4s would change the chiroptical phenomenon in the same manner as the induced Cotton effect in CD. Furthermore, invertible CPL signals can be regulated by metal ion and temperature with stimuli-responsive activities, revealing the convenient and dynamic CPL signals based on G4 polymorphism.