pH responsive translocation of an anticancer drug between cyclodextrin and DNA

Abstract

Ellipticine, a well known anticancer drug, emits intense green color when it is intercalated in DNA. It exhibits blue color inside the nano-cavity of a supramolecular host, γ-cyclodextrin (γ-CD). Inspired by these unique fluorescence switching properties of the anticancer drug, in the present work we have monitored the interplay of the drug between γ-CD and DNA by varying the medium pH as a stimulus. Here, steady-state and picosecond time-resolved fluorescence as well as circular dichroism techniques are employed to decipher the location of the drug inside the γ-CD nano-cavity and DNA. Our results confirm that at higher pH the drug selectively stays at γ-CD, even in the presence of biopolymers and exhibits blue color; whereas at lower pH, it is preferentially located in DNA even in the presence of γ-CD and emits a green color. We believe this kind of pH driven translocation of drugs monitored by fluorescence switching may find possible applications in controlled release of the drug inside cells.